Habitat and Environment of Islands—

Primary and Supplemental Island Sets 

U.S. Department of the Interior

U.S. Geological Survey

Professional Paper 1590

EXPLANATION

Primary Island Set

Supplemental Island Set A

Supplemental Island Set B
By N.C. Matalas and Bernardo F. Grossling

HABITAT AND ENVIRONMENT OF ISLANDS

Primary and Supplemental Island Sets

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1590
Reston, Virginia 2002

Library of Congress Cataloging-in-Publication Data

Matalas, Nicholas C., 1930–

Habitat and environment of islands : primary and supplemental island sets / by N.C.

Matalas and Bernardo F. Grossling.

p. cm. — (U.S. Geological Survey professional paper ; 1590)

Includes bibliographical references (p. ).

ISBN 0-607-99508-4

1. Island ecology. 2. Habitat (Ecology) I. Grossling, Bernardo F., 1918– II. Title. III.

Series.

QH541.5.I8 M27 2002

577.5’2—dc21

2002035440

For sale by the U.S. Geological Survey Information Services

Box 25286, Federal Center,

Denver, CO 80225

Any use of trade, product, or firm names in this report is for

identification purposes only and does not constitute endorsement

by the U.S. Government

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

U.S. Department of the Interior

GALE A. NORTON, Secretary
Preface III

PREFACE

The original intent of the study was to develop a first-order synopsis of island hydrology with an integrated geologic basis on a global scale. As the study progressed, the aim was broadened to provide a framework for subsequent assessments on large regional or global scales of island resources and impacts on those 

resources that are derived from global changes.

Fundamental to the study was the development of a comprehensive framework — a wide range of 

parameters that describe a set of "saltwater" islands sufficiently large to

• Characterize the spatial distribution of the world’s islands;

• Account for all major archipelagos;

• Account for almost all oceanically isolated islands, and 

• Account collectively for a very large proportion of the total area of the world’s islands whereby 

additional islands would only marginally contribute to the representativeness and accountability of the 

island set. 

The comprehensive framework, which is referred to as the “Primary Island Set,” is built on 122 

parameters that describe 1,000 islands. To complement the investigations based on the Primary Island Set, 

two supplemental island sets, Set A – Other Islands (not in the Primary Island Set) and Set B – Lagoonal 

Atolls, are included in the study.

The Primary Island Set, together with the Supplemental Island Sets A and B, provides a framework 

that can be used in various scientific disciplines for their island-based studies on broad regional or global 

scales. 

The study uses an informal, coherent, geophysical organization of the islands that belong to the three 

island sets. The organization is in the form of a global island chain, which is a particular sequential ordering 

of the islands referred to as the “Alisida.” 

The Alisida was developed through a trial-and-error procedure by seeking to strike a balance between 

“minimizing the length of the global chain” and “maximizing the chain’s geophysical coherence.” The fact 

that an objective function cannot be minimized and maximized simultaneously indicates that the Alisida is 

not unique. Global island chains other than the Alisida may better serve disciplines other than those of 

hydrology and geology.
IV HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets
Contents V

CONTENTS

Preface................................................................................................................................................................................... III

Acknowledgments................................................................................................................................................................. XI

Overview ............................................................................................................................................................................... 1

Primary Island Set ................................................................................................................................................................. 3

Identification Parameters............................................................................................................................................. 12

Historical Parameters .................................................................................................................................................. 14

First European Contact...................................................................................................................................... 14

Other Names of the Islands ............................................................................................................................... 17

Summary ........................................................................................................................................................... 21

Geographic Parameters ............................................................................................................................................... 21

Locations of Islands .......................................................................................................................................... 22

Island Affinities ................................................................................................................................................. 25

Topologic Properties of the Islands................................................................................................................... 26

Summary ........................................................................................................................................................... 29

Physiographic Parameters ........................................................................................................................................... 30

Size of Islands ................................................................................................................................................... 30

Quantitative Descriptors of Island Groups........................................................................................................ 33

Qualitative Descriptors of Island Topographies ................................................................................................ 33

Qualitative Descriptors of Island Shapes .......................................................................................................... 36

Dimensional Measures of Islands ..................................................................................................................... 39

Summary ........................................................................................................................................................... 40

Geologic Parameters ................................................................................................................................................... 41

Relational Features of the Earth’s Surface ........................................................................................................ 41

Geologic Classification ..................................................................................................................................... 44

Volcanism .......................................................................................................................................................... 45

Geologic Topology ............................................................................................................................................ 45

Summary ........................................................................................................................................................... 45

Hydrologic Parameters................................................................................................................................................ 53

Hydrologic Sketch............................................................................................................................................. 53

Summary ........................................................................................................................................................... 54

Economic Parameters.................................................................................................................................................. 60

Sovereignty of Islands....................................................................................................................................... 60

Populations of Islands and Principal Centers.................................................................................................... 64

Principal Seaports and Airports......................................................................................................................... 69

Local Time ........................................................................................................................................................ 72

Summary ........................................................................................................................................................... 72

Environmental Parameters........................................................................................................................................... 73

Local Meteorology of Islands ........................................................................................................................... 74

Climatic Markers............................................................................................................................................... 76

Hydrologic Classes............................................................................................................................................ 82

Summary ........................................................................................................................................................... 82

Supplemental Island Sets A and B ........................................................................................................................................ 85

Windows on the Primary Island Set ...................................................................................................................................... 90

References Cited ................................................................................................................................................................... 91

Abbreviations and Notation .................................................................................................................................................. 92

Glossary................................................................................................................................................................................. 95

Foreign Terms.............................................................................................................................................................. 95

Technical Terms .......................................................................................................................................................... 95
VI Contents

FIGURES

1-13. Maps showing:

1. Global distribution of the Primary Island Set and Supplemental Island Sets A snd B..................................4

2. The world without islands .............................................................................................................................5

3. The world without continents........................................................................................................................6

4. Track of the Alisida per 100 island segments................................................................................................15

5. Extent of the domain of first European contact .............................................................................................18

6. Global perspective on the temporal distribution of first European contact with islands ...............................19

7. Global distribution of first European contact with islands per sponsorship of expedition............................20

8. Boundaries of oceanic regions.......................................................................................................................23

9. Distance along the track of the Alisida, expressed as equivalent circumferences of the Earth.....................27

10. Relative locations of the islands and their antipodes...................................................................................28

11. Global perspective on the distribution of the area of the islands.................................................................31

12. Global perspective on the distribution of the elevations of the highest peaks on the islands......................32

13. Global distribution of islands per terrain group...........................................................................................35

Figure 14. Shape comparison of generic and real islands ...........................................................................................37

15-38. Maps showing:

15. Global distribution of island shapes ............................................................................................................38

16. Global distribution of islands per lithospheric plates ..................................................................................42

17. Global distribution of islands per Quipu category.......................................................................................43

18. Global distribution of islands per geologic class.........................................................................................46

19. Global distribution of islands per geologic species conditioned on geologic class A.................................47

20. Global distribution of islands per geologic species conditioned on geologic class C.................................48

21. Global distribution of islands per geologic species conditioned on geologic class O.................................49

22. Global distribution of islands composed of carbonate or volcanic rocks....................................................50

23. Global distribution of islands per most recent period of volcanic eruption ................................................52

24. Global distribution of island hydrologic features–Perennial or seasonal rivers ..........................................55

25. Global distribution of island hydrologic features–Perennial or seasonal springs .......................................56

26. Global distribution of island hydrologic features–Fresh- or brackish-water lakes......................................57

27. Global distribution of island hydrologic feature–Wetlands.........................................................................58

28. Global distribution of island hydrologic feature–Surface reservoir ............................................................59

29. Global distribution of islands relating to the five highest frequencies of sovereignty ................................65

30. Global perspective on the distribution of island population density ...........................................................67

31. Global distribution of the types of island principal centers.........................................................................68

32. Global distribution of offshore transportation facilities ..............................................................................71

33. Global distribution of island meteorological stations..................................................................................75

34. Global distribution of islands per polar climatic state.................................................................................77

35. Global distribution of islands per temperate climatic state .........................................................................78

36. Global distribution of islands per tropical climatic state.............................................................................79

37. Global distribution of islands per scale of glaciation ..................................................................................80

38. Global distribution of islands per hydrologic class .....................................................................................83

PLATES (in back pocket)

1. Track of the Alisida and identification numbers of islands in the Primary Island Set

BOOKLET (in back pocket)

Locator guide for islands in the Primary Island Set
Contents VII

TABLES

1. Distribution of parameters, by category ..................................................................................................................3

2. Parameters of the islands that belong to the Primary Island Set..............................................................................7

3. Parameter coverages of islands by information source and category......................................................................11

4. Duplicate island names............................................................................................................................................16

5. Island coverage, by historical parameter .................................................................................................................21

6. Oceanic regions .......................................................................................................................................................22

7. Oceanic subregions..................................................................................................................................................24

8. Island coverage, by geographic parameter ..............................................................................................................29

9. Codification of island topographies.........................................................................................................................34

10. Descriptions of generic shapes ..............................................................................................................................36

11. Island coverage, by physiographic parameter .......................................................................................................40

12. Lithospheric plates.................................................................................................................................................41

13. Quipu categories ....................................................................................................................................................41

14. Continent and island geologic types......................................................................................................................44

15. Geologic distance between two islands of specific geologic types .......................................................................51

16. Island coverage, by geologic parameter ................................................................................................................53

17. Island coverage, by hydrologic parameter.............................................................................................................54

18. Distribution of islands by country .........................................................................................................................61

19. Types of principal centers......................................................................................................................................66

20. Classification of seaport types ...............................................................................................................................70

21. Island coverage, by economic parameter...............................................................................................................72

22. Island climates .......................................................................................................................................................76

23. Scale of island glaciation.......................................................................................................................................76

24. Distribution of islands, by hydrologic features and class......................................................................................81

25. Island coverage, by environmental parameter .......................................................................................................84

26. Distributions of Supplemental Island Sets A and B parameters, by category .......................................................85

27. Parameters of Supplemental Island Set A..............................................................................................................86

28. Parameters of Supplemental Island Set B..............................................................................................................87

29. Island coverage, by parameters of Supplemental Island Set A..............................................................................88

30. Island coverage, by parameters of Supplemental Island Set B..............................................................................89

31. Windows on the Primary Island Set.......................................................................................................................90

32. Full account of abbreviations and notations ..........................................................................................................92

33. Dictionary ..............................................................................................................................................................95

CONVERSION FACTORS

Multiply by to obtain

meter (m) 3.2808 foot

kilometer (km) 0.6214 mile

square meter (m2

) 10.76 square feet

square meter (m2) 0.0002471 acre

square kilometer (km2

) 0.3861 square mile

degree Celcius (°C) °F=1.8 temp °C + 32 degree Fahrenheit (°F)
VIII Contents

CONTENTS of COMPANION COMPACT DISC

Windows on the Primary Island Set ......................................................................................................................................102

Window 1—Basic Information....................................................................................................................................104

Window 2—Historical Information.............................................................................................................................126

Window 3—Geographic Information..........................................................................................................................148

Window 4—Physiographic Information......................................................................................................................170

Window 5—Topologic Information ............................................................................................................................192

Window 6—Geophysical Information.........................................................................................................................214

Window 7—Geologic Neighbors ................................................................................................................................237

Window 8—Demographic Information.......................................................................................................................259

Window 9—Geographic–Geologic–Sovereignty Affinities ........................................................................................281

Window 10—Port and Airport Information ................................................................................................................303

Window 11—Meteorologic Information.....................................................................................................................325

Window 12—Climatic Information.............................................................................................................................347

Window 13—Names of Islands...................................................................................................................................369

Windows on the Supplemental Island Sets............................................................................................................................403

Window A—Other Islands .........................................................................................................................................404

Window B—Lagoonal Atolls .....................................................................................................................................414

Appendixes ............................................................................................................................................................................424

Appendix A—Size of the Earth...................................................................................................................................424

Appendix B—Geometric Measures of Islands............................................................................................................428

Appendix C—Notion of Compactness........................................................................................................................433

Appendix D—Generation of Thematic Maps .............................................................................................................439

Appendix E—Global Distribution of Islands ..............................................................................................................441

Appendix F—Partial Tracks of the Alisida .................................................................................................................445

Appendix G—Global Distributions of Specific Hydrologic Features.........................................................................456

Appendix H—Global Distribution of Islands per Sovereignty ...................................................................................463

Appendix I—Global Distributions of Specific Climatic Markers ...............................................................................482

Appendix J—Islands–Maps and General Information ................................................................................................491

Appendix K—Island Notes .........................................................................................................................................692

Selected Bibliography ...........................................................................................................................................................729

Bibliography ..........................................................................................................................................................................771

FIGURES

39. Richardson’s shapes...............................................................................................................................................435

40. Island shapes..........................................................................................................................................................437

41–85. Maps showing:

41. Global distribution of islands that belong to the Primary Island Set ..........................................................442

42. Global distribution of islands that belong to the Supplemental Island Set A..............................................443

43. Global distribution of islands that belong to the Supplemental Island Set B .............................................444

44. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 1–100 ........446

45. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 101–200 ....447

46. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 201–300 ....448

47. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 301–400 ....449

48. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 401–500 ....450

49. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 501–600 ....451

50. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 601–700 ....452
Contents IX

51. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 701–800 .....453

52. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 801–900 .....454

53. Partial track of the Alisida: subsegments of the 100-island segment, identification numbers 901–1000 ...455

54. Global distribution of an island hydrologic feature—perennial rivers .......................................................457

55. Global distribution of an island hydrologic feature—seasonal rivers ........................................................458

56. Global distribution of an island hydrologic feature—perennial springs .....................................................459

57. Global distribution of an island hydrologic feature—seasonal springs.......................................................460

58. Global distribution of an island hydrologic feature—freshwater lakes.......................................................461

59. Global distribution of an island hydrologic feature—brackish water lakes ................................................462

60. Global distribution of islands per sovereignty—Antigua and Barbuda, Argentina, Australia, Bahamas, 

and Bahrain..........................................................................................................................................464

61. Global distribution of islands per sovereignty—Barbados, Belau, Brazil, Brunei, and Burma ..................465

62. Global distribution of islands per sovereignty—Canada, Cape Verde, Chile, China, and Colombia..........466

63. Global distribution of islands per sovereignty—Comoros, Cook Islands, Costa Rica, Croatia, 

and Cuba..............................................................................................................................................467

64. Global distribution of islands per sovereignty—Cyprus, Denmark, Dominica, Dominican Republic, 

and Ecuador .........................................................................................................................................468

65. Global distribution of islands per sovereignty—Equatorial Guinea, Estonia, Federated States of 

Micronesia, Fiji, and Finland...............................................................................................................469

66. Global distribution of islands per sovereignty—France, Germany, Greece, Grenada, and Guinea ............470

67. Global distribution of islands per sovereignty—Haiti, Honduras, Iceland, India, and Indonesia ...............471

68. Global distribution of islands per sovereignty—Iran, Ireland, Italy, Jamaica, and Japan ...........................472

69. Global distribution of islands per sovereignty—Kiribati, Madagascar, Malaysia, Maldives, and Malta....473

70. Global distribution of islands per sovereignty—Marshall Islands, Mauritius, Mexico, Nauru, and 

the Netherlands....................................................................................................................................474

71. Global distribution of islands per sovereignty—New Zealand, Norway, Oman, Panama, and 

Papua New Guinea ..............................................................................................................................475

72. Global distribution of islands per sovereignty—Peru, Philippines, Poland, Portugal, and Russia .............476

73. Global distribution of islands per sovereignty—Saint Kitts and Nevis, Saint Lucia, Saint Vincent 

and the Grenadines, Sao Tome and Princip, and the Seychelles .........................................................477

74. Global distribution of islands per sovereignty—Singapore, Solomon Islands, South Africa, 

South Korea, and Spain .......................................................................................................................478

75. Global distribution of islands per sovereignty—Sri Lanka, Sweden, Tanzania, Thailand, and Tonga........479

76. Global distribution of islands per sovereignty—Trinidad and Tobago, Turkey, Tuvalu, 

United Kingdom, and United States....................................................................................................480

77. Global distribution of islands per sovereignty—Vanuatu, Venezuela, Vietnam, Western Samoa, 

and Yemen............................................................................................................................................481

78. Global distribution of an island climate marker—permanent ice................................................................483

79. Global distribution of an island climate marker—permafrost.....................................................................484

80. Global distribution of an island climate marker—temperate-zone peat......................................................485

81. Global distribution of an island climate marker—seasonal ice ...................................................................486

82. Global distribution of an island climate marker—mangroves.....................................................................487

83. Global distribution of an island climate marker—corals.............................................................................488

84. Global distribution of an island climate marker—tropical peat ..................................................................489

85. Global distribution of an island climate marker—palms.............................................................................490

86. Island maps and general information for islands ordered alphabetically ........................................................................492

87. Island maps and general information for islands ordered sequentially per the Alisida...................................................592

TABLES

31. Windows on the Primary Island Set.......................................................................................................................103

32. Parameters that provide basic information on the islands in the Primary Island Set ............................................104

33. Abbreviations and notation that relate to the parameters in Window 1 .................................................................105

34. Basic information—Islands ordered alphabetically by name................................................................................106

35. Parameters that provide historical information on the islands in the Primary Island Set......................................126
X Contents

36. Abbreviations and notation that relate to the parameters in Window 2.................................................................127

37. Historical information—Islands ordered alphabetically by name.........................................................................128

38. Parameters that provide geographic information on the islands in the Primary Island Set...................................148

39. Abbreviations and notation that relate to the parameters in Window 3.................................................................149

40. Geographic information—Islands ordered alphabetically by name......................................................................150

41. Parameters that provide physiographic information on the islands in the Primary Island Set..............................170

42. Abbreviations and notation that relate to the parameters in Window 4.................................................................171

43. Physiographic information—Islands ordered alphabetically by name..................................................................172

44. Parameters that provide topologic information on the islands in the Primary Island Set .....................................192

45. Abbreviations and notation that relate to the parameters in Window 5.................................................................193

46. Topologic information—Islands ordered per the Alisida ......................................................................................194

47. Parameters that provide geophysical information on the islands in the Primary Island Set..................................214

48. Abbreviations and notation that relate to the parameters in Window 6.................................................................215

49. Geophysical information—Islands ordered per the Alisida ..................................................................................217

50. Parameters that provide information on the geologic neighbors among the islands in the Primary Island Set ....237

51. Abbreviations and notation that relate to the parameters in Window 7.................................................................238

52. Geologic neighbors—Islands ordered per the Alisida...........................................................................................239

53. Parameters that provide demographic information on the islands in the Primary Island Set................................259

54. Abbreviations and notation that relate to the parameters in Window 8.................................................................260

55. Demographic information—Islands ordered alphabetically by name within alphabetic ordering 

by sovereignty................................................................................................................................................261

56. Parameters that provide information on the geographic, geologic, and sovereignty affinities among 

the islands in the Primary Island Set .............................................................................................................281

57. Abbreviations and notation that relate to the parameters in Window 9.................................................................282

58. Geographic–geologic–sovereignty affinities—Islands ordered per the Alisida ....................................................283

59. Parameters that provide port and airport information on the islands in the Primary Island Set............................303

60. Abbreviations and notation that relate to the parameters in Window 10...............................................................304

61. Seaport and airport information—Islands ordered alphabetically by name..........................................................305

62. Parameters that provide meteorologic information on the islands in the Primary Island Set ...............................325

63. Abbreviations and notation that relate to the parameters in Window 11...............................................................326

64. Meteorologic information—Islands ordered alphabetically by name ...................................................................327

65. Parameters that provide climatic information on the islands in the Primary Island Set........................................347

66. Abbreviations and notation that relate to the parameters in Window 12...............................................................348

67. Cimatic information—Islands ordered alphabetically by name............................................................................349

68. Names of islands in the Primary Island Set...........................................................................................................369

69. Abbreviations and notation that relate to the parameters in Window 13...............................................................369

70. Names of islands—Islands ordered alphabetically by name.................................................................................370

71. Parameters that describe the Supplemental Island Set A islands...........................................................................404

72. Abbreviations and notation that relate to the parameters in Window W-A ...........................................................405

73. Other islands—Islands ordered alphabetically by name .......................................................................................406

74. Parameters that describe the Supplemental Island Set B islands...........................................................................414

75. Abbreviations and notation that relate to the parameters in Window W-B............................................................415

76. Lagoonal atolls—Atolls ordered alphabetically by name .....................................................................................416

77. Richardson’s experimental results.........................................................................................................................435

78. Experimental results on Richardson’s shapes—U.S. Geological Survey observers .............................................436

79. Experimental results on island shapes—U.S. Geological Survey observers.........................................................438

80. Island–literature linkage—Islands ordered alphabetically by name .....................................................................730
Acknowledgements XI

ACKNOWLEDGMENTS

For many of the islands in the study, the literature was of little help for obtaining information about certain 

characteristics of the islands. This was particularly so in relation to hydrologic and geometric characteristics. Much 

of the short-fall of the hydrologic literature was overcome through contacts with technical personnel who had firsthand hydrologic knowledge about the islands. Establishment of the contacts was undertaken with the encouragement and support of the British Geological Survey, Wallingford, United Kingdom. 

The following individuals helped provide the hydrologic characterizations of the islands as formulated in the 

study:

JOHN S. BADER, U.S. Geological Survey, Menlo Park, California

MAX BERAN, Institute of Hydrology, Wallingford, United Kingdom

S.K. BOOTH, Office of Mineral Development, Suva, Fiji

BENEDITO P.F. BRAGA, University of Sao Paulo, Sao Paulo, Brazil

J.T. CALLAHAN, U.S. Geological Survey (retired), Glendale, Arizona

WILLIAM J. CAMPBELL, U.S. Geological Survey (deceased), Tacoma, Washington

JESUS CARRERA, Universitat Politecnica de Catalunya, Barcelona, Spain

FI-JOHN CHANG, National University of Taiwan, Taiwan

C.S. CHENEY, Geology, Mines and Rural Water Supply, Port Vila, Vanuatu

C-L CHIU, University of Pittsburgh, Pittsburgh, Pennsylvania

K.C. ANDER CHOW, Atria Engineering Hydraulics, Inc., Mississauga, Ontario, Canada

EMILIO CUSTODIO, Universitat Politecnica de Catalunya, Barcelona, Spain

TRIGO D'ABREU, Instituto de Estudos Para o Desenvoirimento, Lisboa, Portugal

ELIAS DAVIDSEN, E.D. Verkfrodi, Torshavn, Faroe Islands

DAN DAVIS, U.S. Geological Survey (deceased), Honolulu, Hawaii

JAOQUIM DELGADO, Sao Vincente, Cape Verde

PEDRO L. DIAZ, U.S. Geological Survey, San Juan, Puerto Rico

THORLEIFUR EINARSSON, University of Iceland, Reykjavik, Iceland

TONY FALKLAND, Minister for Housing and Urban Services, Australian Capital Territory, Canberra, 

 Australia

JEAN-CHARLES FONTES, Universite Paris-Sud, Orsay-Cedex, France

DEO YIN FOO, Northern Territory Power and Water Authority, Darwin, Australia

PHILIPPE FREY, Parc de la Providence, Reunion Island, France

IAN N. GALE, British Geological Survey, Wallingford, United Kingdom
XII Acknowledgements

ROBERT W. GATLIFF, Ministry of Lands, Survey and Natural Resources, Nukualofa, Tonga

E.V. GIUSTI, Compagnia Generale Ripreseaeree, Parma, Italy

GYLFI MAR GUDBERGSSON, University of Iceland, Reykjavik, Iceland

NILGUN HARMANCIOGLU, Dokuz Eylul University, Izmir, Turkey

LINDA HARRIS, U.S. Geological Survey, Anchorage, Alaska

MICHAEL HAWKINS, Ministry of Natural Resources, Geology Division, Honiara, Solomon Islands

JESSE N. JASPER, Environment Canada, Inland Waters, Yellowknife, Northwest Territories, Canada

J. JOHANSSON, Swedish Natural Science Research Council, Stockholm, Sweden

PAUL JOHNSON, Imperial College, London, United Kingdom

CLAUS KERN-HANSEN, Greenland Technical Survey, Hydro-Technical Division, Copenhagen, Denmark

JAN-TAI KUO, National Taiwan University, Taipei, Taiwan

SADI LAPORTE, Instituto Costarricense de Electricidad, San Jose, Costa Rica

ANDREW LIVINGSTON, Tasmanian Hydro Electric Commission, Hobart, Australia

THOMAS MADDOCK III, University of Arizona, Tucson, Arizona

NICHOLAS MARGARIS, University of the Aegean, Athens, Greece

TERRY MARSH, Institute of Hydrology, Wallingford, United Kingdom

JOHN MCALPINE, Commonwealth Scientific and Industrial Research Organization, St. Lucia, Australia

M.P. MOSLEY, Department of Scientific and Industrial Research, Wellington, New Zealand

HREGGVIDUR NORDDAHL, University of Iceland, Reykjavik, Iceland

TERRENCE O'DONNELL, Journal of the International Association of Hydrologic Sciences, Editor, 

 Wallingford, United Kingdom

A.R. PERKS, Environment Canada, Quebec, Canada

ERIC PLATTE, University of Karlsruhe, Karlsruhe, Germany

A.R. RAO, Purdue University, West Lafayette, Indiana

K.S. RAO, Indian Institute of Science, Bangalore, India

HUGH RIDDLE, Metropolitan Washington Airport Authority (deceased), Alexandria, Virginia

N.S. ROBINS, British Geological Survey, Wallingford, United Kingdom

ROBERT ROWLAND, U.S. Geological Survey (retired), Reston, Virginia

ZHENG RUGANG, Ministry of Water Resource, Beijing, People's Republic of China

MAMDOUH SHAHIN, International Institute for Hydraulic and Environmental Engineering (retired),

Delft, The Netherlands

SABINE SEIERT, University of Karlsruhe, Karlsruhe, Germany

I.A. SHIKLOMANOV, State Hydrological Institute, Leningrad, Russia

ENG BAN SHUY, Nanyang Technological University, Singapore
Acknowledgements XIII

COSTAS SOPHOULIS, University of the Aegean, Athens, Greece

BRUCE STEWART, Bureau of Meteorology, Melbourne, Australia

KUNIYOSHI TAKEUCHI, Yamanashi University, Kofu, Japan

TOM TAYLOR, U.S. Geological Survey, Anchorage, Alaska

M.R.A. THOMSON, British Antarctic Survey, Cambridge, United Kingdom

ARTURO E. TORRES, U.S. Geological Survey, San Juan, Puerto Rico

BRANKO VUJASINOVIC, Zagreb, Croatia

RICHARD S. WILLIAMS, U.S. Geological Survey, Reston, Virginia

BJORN WOLD, Norwegian Water Resources and Energy Administration, Oslo, Norway

Several members of the U.S. Geological Survey provided research assistance and contributed to the production of this report. CASSIE PUFNOCK, Reston, Virginia, assisted in the extensive and detailed library research 

and in the development and maintance of the computerized data files. PATRICIA J. SHADE and PATRICIA S. 

FUJII, Honolulu, Hawaii, handled all matters that related to the digitization of the mapped coastlines for 268 

islands. JANE RUSSELL, Reston, Virginia, provided technical guidance on developing the graphics. The production of the world maps that depict the global distributions of island characteristics is due to the efforts of THOMAS 

L. JOHNSON and GREG BAIER.

To all those named above, we express our deep appreciation. Any errors of omission or commission are, of 

course, those of the authors.
XIV Acknowledgements
Overview 1

Habitat and Environment of Islands: 

Primary and Supplemental Island Sets 

by N.C. Matalas and Bernardo F. Grossling

OVERVIEW

Islands have long been an object of scientific 

interest. Notably Charles Darwin, while on the roundthe-world voyage of the Beagle (1831–1836), developed his ideas on biological evolution following his 

speculations on the isolation of various species on the 

Galapagos Islands in the Pacific Ocean and on the biophysical evolution of coral atolls upon visiting the 

island of Cocos-Keeling in the Indian Ocean. In the 

succeeding years, a large body of literature on islands 

has developed, primarily within the disciplines of geology and biology. The summary account by MacArthur 

and Wilson (1967) remains an excellent introduction to 

biogeographic theory of islands. Menard (1986) provided a summary account of the geologic evolution and 

demise of islands, particularly oceanic islands and 

islands in island arcs. Nunn (1994) placed island studies within the context of current interest in global 

change. Island-based studies can provide a framework 

approximating natural, controlled scientific experiments — the isolation of various properties of islands 

to study the effects on those properties through the 

relations of other properties, endogenous or exogenous, to the islands — a process referred to in engineering as “defining a free-body cut.” 

To develop an island framework useful for interdisciplinary island-based studies, a general synthesis 

along multidisciplinary lines of the world’s “saltwater” 

islands was undertaken on the basis of a Primary Island 

Set of 1,000 specific islands characterized by 122 

parameters. The suitability of the synthesis is enhanced 

by including information on islands that belong to two 

Supplemental Island Sets — A, which consists of 386 

islands characterized by 14 parameters, and B, of 368 

islands characterized by 17 parameters. A detailed 

description of the parameters, their coverages of the 

islands, and the values of the parameters structured for 

various disciplines follows.

The sample space for selecting islands to form 

the Primary Island Set was bound as follows:

• Excluded from the sample space were islands 

within freshwater bodies, lakes, and rivers, and 

(or) on continents or on islands, as well as islands 

that are parts of the deltas of rivers that discharge 

to the sea;

• Grønland (Greenland), which is generally considered to be the world’s largest island, was preselected, thereby fixing the upper bound on the areal 

size of any island;

• No limit was imposed on the lower bound of the 

areal size of an island;

• Dry-lagoon atolls, particularly raised atolls, and 

islets of atolls, but not atolls per se, were considered to be within the sample space;

• In the case of two islands separated by a “narrow” 

and “shallow” channel, if one island was selected, 

then the other also was selected — this conditional selection avoided the establishment of accurate criteria on the width and depth of channels for 

judging whether two islands were considered to 

be effectively one, information that in some cases 

would be difficult to obtain;

• Along continental margins, islands that mark the 

outer oceanic extent of archipelagos were considered, but allowing for the selection of an exceptionally large “interior” island whose area makes 

up a large proportion of the total area of the archipelago, and
2 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

• On the basis of prior information, certain islands 

were, in effect, preselected because of their scientific, social, or historical significance.

Given the sample space, no rigorous criteria 

were imposed upon the selection of islands. However, 

for an island to be a member of the Primary Island Set, 

values of its area and the elevation of its highest peak 

had to be ascertained. The islands that make up the Primary Island Set were selected in a systematic manner 

to assure that the following conditions were met:

• Almost all geographically recognized archipelagos were well represented;

• The total areas of the selected islands were large 

proportions of the total areas of the archipelagos 

themselves;

• Almost all isolated islands, regardless of their 

areal size, were included in the Primary Island Set;

• The “linear” extent of the emerged portions of 

oceanic mountain chains were well delineated, 

and

• In the aggregate, the selected islands provided, 

albeit subjectively assessed, a high degree of representativeness relative to the geographic distribution, and hence the climatic setting, of the world’s 

saltwater islands.

In the process of developing the Primary Island 

Set, more than 1,000 islands were taken into consideration. The Primary Island Set was refined several times; 

that is, on several occasions, various islands were 

extracted and replaced by other islands to satisfy the 

above conditions “better.” The islands that were 

extracted, as well as other islands that were considered, 

but never included in a tentative makeup of the Primary 

Island Set, form the Supplemental Island Set A, which 

consists of 386 islands. 

To provide a representative geographic coverage 

of the world’s atolls and to allow for discussion at 

the individual island level, a few atoll islets were 

included in the Primary Island Set. A more detailed 

geographic coverage of the world’s atolls is provided 

by the 368 lagoonal atolls that form the Supplemental 

Island Set B. 

In a sense, the three island sets are not mutually 

exclusive — some atoll islets in the Primary Island Set 

and in the Supplemental Island Set A correspond to 

atolls in the Supplemental Island Set B. The redundancy is transparent by means of certain parameters 

that identify the islands and mark their geographic 

locations, and, therefore the redundancy can be readily 

eliminated by extracting the particular islands from 

their respective sets, thereby slightly reducing the size 

of the sets; that is, the number of islands forming the 

sets.

The parameters that belong to the three island 

sets may be grouped into eight categories. For the primary islands, their parameters are distributed over each 

of the islands, whereas for the Supplemental Island 

Sets A and B islands, their parameters are distributed 

over five of the eight categories; the three empty categories are the same for the two sets (table 1).

The parameters assume either alpha or numeric 

values that were obtained by one or more of the following basic means:

• L — Review of scientific publications, government reports and maps, atlases, and geographic 

gazetteers;

• N1 — Use of definitions and concepts developed 

in the study;

• N2 — Use of established formulas, algorithms, 

and logical operations, and

• N3 — Personal communication with colleagues 

who have first-hand pertinent knowledge of specific islands.

For some islands, values of the parameters could 

not be given for various reasons. If for a particular 

island, the alphanumeric value that relates to a specific 

parameter could not be ascertained, then one of four 

symbols is used to indicate the reason why a specific 

alphanumeric value is not given. The four symbols and 

their interpretations are as follows:

• † — A specific value for the parameter is not 

applicable;

• * — The parameter value could not be determined 

owing to limited resources of the study;

• ‡ — Search for the parameter value was unsuccessful, and

• # — Information sources were not adequate to 

ascertain further detail as to the parameter value.

At most, the island coverage by a parameter is 

1,000 islands relative to the Primary Island Set, 386 relative to the Supplemental Island Set A, and 368 relative 
Primary Island Set 3

to the Supplemental Island Set B. In those cases where 

specific alphanumeric values could not be ascertained 

for particular parameters, the island coverages by those 

parameters are accordingly limited. 

Descriptions of the parameters and their island 

coverages are accompanied by maps that show the global distribution of the alphanumeric values for various 

parameters. Each map is based on a Gall’s Stereographic Cylindrical projection at an approximate scale 

of 1:175,000,000 and is structured such that the map is 

centered on the Pacific Ocean wherein the largest share 

of the world’s islands is concentrated. In these maps, 

longitude “begins” (left side of map) at 35° and “ends” 

(right side of map) at 35°. To show the full extent of the 

Earth’s dry-land surface, each map extends from latitude -87° (south) to latitude 87° (north).

Alphanumeric values of the parameters are 

viewed, so to speak, through 13 “windows” on the Primary Island Set — each window being a datafile that 

provides a distinct description of the islands conditioned by a specific subset of the parameters. Because 

the islands in the Supplemental Island Sets A and B are 

described by fewer parameters, the alphanumeric values of their parameters are “viewed” through only two 

windows, one for each of the Supplemental Island Sets.

The general distribution over the Earth’s surface 

of the islands that belong to the Primary Island Set and 

to the Supplemental Island Sets A and B is illustrated 

in figure 1. How the world would appear if the continents, but not the islands, or if the islands, but not the 

continents, existed is illustrated by figures 2 and 3, 

respectively. The global distributions of the three sets 

of islands are shown separately in Appendix E.

PRIMARY ISLAND SET

The 1,000 islands that belong to the Primary 

Island Set are described by 122 parameters distributed 

over the eight-parameter categories. Under each category, the parameters, the island coverages of the 

parameters, and the information sources from which 

the alphanumeric values of the parameters were 

obtained are given in table 2; for those parameters 

whose alphanumeric values were obtained from more 

than one source, the primary source is noted first.

The Primary Island Set may be viewed as a 

matrix that consists of 1,000 rows (islands) and 122 

columns (parameters), the total number of cells being 

122,000. The grand coverage of islands by the 122 

parameters, which is given by the total number of cells 

that contain specific alphanumeric values or the symbol 

† that denotes that a specific alphanumeric value is not 

applicable, may be expressed in a normalized form as 

the grand average number of islands covered by the 

parameter; that is, as the ratio of the grand coverage to 

the total number of parameters. 

The parameter coverages of the islands in terms 

of primary information sources and categories are 

given in table 3.

Table 1. Distribution of parameters, by category

[f, frequency; cf, cumulative frequency]

Number of parameters

Primary Island Set Supplemental Island Set A Supplemental Island Set B

Count Category f cf f cf f cf

1 Identification 2 2 2 2 2 2

2 Historical 8 10 0 2 0 2

3 Geographic 22 32 5 7 6 8

4 Physiographic 19 51 2 9 5 13

5 Geologic 15 66 2 11 1 14

6 Hydrologic 9 75 0 11 0 14

7 Economic 30 105 1 12 1 15

8 Environmental 17 122 0 12 0 15
4 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Primary Island SetSupplemental Island Set ASupplemental Island Set B

Figure 1. Global distribution of the Primary Island Set and Supplemental Island Sets A and B.
Primary Island Set 5 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

Figure 2. The world without islands.
6 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

Figure 3. The world without continents.
Primary Island Set 7

Table 2. Parameters of the islands that belong to the Primary Island Set 

[L, review of scientific publications, government reports and maps, atlases, and geographic gazetteers; N1, definitions or concepts developed in the 

study; N2, established formulas, algorithms, and logical operations; N3, personal communication of colleagues; ID, identification.]

Count

Parameter descriptions Islands

covered

Information 

source Cumulative Category

Identification

1 1 Island name 1,000 L

2 2 Island ID number per a specific geophysically based sequential order 

of the islands

1,000 N1

Historical

3 1 Code that identifies islands that are within or outside the domain of 

earliest European contact after A.D. 1400

1,000 L

4 2 Year of earliest European contact with a specific island 750 L

5 3 Captain of European expedition that made earliest contact with a 

specific island

749 L

6 4 European nation that sponsored expedition that made earliest contact 

with a specific island

747 L

7 5 Name given to island upon its earliest European contact 520 L

8 6 Conventional name of island 1,000 L

9 7 Other name of island 1,000 L

10 8 Code that indicates historical context of an island’s alternate/former 

name

1,000 L

Geographic

11 1 Latitude of island reference point 1,000 L

12 2 Longitude of island reference point 1,000 L

13 3 Oceanic region in which island is located 1,000 N1

14 4 Oceanic subregion in which island is located 1,000 N1

15 5 Island group to which an island belongs 1,000 L

16 6 Code that indicates whether or not group name was taken from 

geographic literature

1,000 L

17 7 Island group ID per specific sequential order of the islands 1,000 N1

18 8 Island subgroup to which an island belongs 1,000 L

19 9 Interisland positional distance relative to a specific sequential order 

of the islands

1,000 N2

20 10 Cumulative interisland positional distances relative to a specific 

sequential order of the islands

1,000 N2

21 11 Name of the island nearest to a specific island 1,000 N2

22 12 ID number of the island nearest to a specific island 1,000 N2

23 13 Positional distance of the nearest island to a specific island 1,000 N2

24 14 Virtual distance of the nearest island to a specific island 1,000 N2

25 15 Name of the island farthest from a specific island 1,000 N2
8 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

26 16 ID number of the island farthest from a specific island 1,000 N2

27 17 Region of the island farthest from a specific island 1,000 N1

28 18 Positional distance to the island farthest from a specific island 1,000 N2

29 19 Latitude of an island’s antipode 1,000 N2

30 20 Longitude of an island’s antipode 1,000 N2

31 21 Ocean in which an island’s antipode is located 1,000 N2

32 22 Continent on which an island’s antipode is located 1,000 N2

Physiographic

33 1 Area of island 1,000 L

34 2 Name of island’s highest peak 552 L

35 3 Elevation of highest peak 1,000 L

36 4 Latitude of highest peak 740 L, N3

37 5 Longitude of highest peak 740 L, N3

38 6 Number of islands in group containing a specific island 1,000 N1

39 7 Area of island group 1,000 N1

40 8 Percentage of island area relative to island group area 1,000 N2

41 9 Topographic type of island 660 N1

42 10 Shape type of island 997 N1

43 11 Length of island 734 L

44 12 Width of island 734 L

45 13 Radius of effective circle 1,000 N2

46 14 Radius of gyration 267 N2

47 15 Perimeter of island 318 L, N2

48 16 Fractal dimension of an island’s coastline 267 N2

49 17 Compactness of an island as a function of length and width 734 N2

50 18 Compactness of an island as a function of area and perimeter 267 N2

51 19 Compactness of an island as a function of area and moment of inertia 267 N2

Geologic

52 1 Lithospheric plate on which island is located 1,000 N1

53 2 Quipu 1,000 N1

54 3 Geologic type of an island 1,000 N1

55 4 Geologic class of an island group containing a specific island 1,000 N1

56 5 Volcanism 1,000 L

Table 2. Parameters of the islands that belong to the Primary Island Set 

[L, review of scientific publications, government reports and maps, atlases, and geographic gazetteers; N1, definitions or concepts developed in the 

study; N2, established formulas, algorithms, and logical operations; N3, personal communication of colleagues; ID, identification.]

Count

Parameter descriptions Islands

covered

Information 

source Cumulative Category

—Continued
Primary Island Set 9

57 6 Interisland geologic distance relative to a specific sequential order of 

the islands

1,000 N1

58 7 Name of nearest type C island from a specific island 1,000 N1

59 8 ID number of nearest type C island from a specific island 1,000 N1

60 9 Distance to nearest type C island from a specific island 1,000 N1

61 10 Name of nearest type A island from a specific island 1,000 N1

62 11 ID number of nearest type A island from a specific island 1,000 N1

63 12 Distance to nearest type A island from a specific island 1,000 N1

64 13 Name of nearest type O island from a specific island 1,000 N1

65 14 ID number of nearest type O island from a specific island 1,000 N1

66 15 Distance to nearest type O island from a specific island 1,000 N1

Hydrologic

67 1 Code that indicates extent of completeness of an island’s hydrologic 

sketch

1,000 N3

68 2 Presence or absence of perennial rivers on island 794 N3

69 3 Presence or absence of seasonal rivers on island 784 N3

70 4 Presence or absence of perennial springs on island 776 N3

71 5 Presence or absence of seasonal springs on island 727 N3

72 6 Presence or absence of wetlands on island 715 N3

73 7 Presence or absence of freshwater lakes on island 815 N3

74 8 Presence or absence of brackish water lakes on island 690 N3

75 9 Presence or absence of surface reservoirs on island 812 N3

Economic

76 1 Sovereignty of an island 1,000 L, N3

77 2 Sovereignty ID per rank order of number islands under specific 

sovereinty

1,000 L, N2

78 3 Code that indicates whether or not an island is permanently 

inhabited

964 L, N3

79 4 Census of island’s population 759 L, N3

80 5 Year of census 729 L, N3

81 6 Population density of an island 759 N2

82 7 Code that indicates whether or not an island has a principal center 752 L

83 8 Name of principal center 749 L

84 9 Census of principal center’s population 340 L

85 10 Year of census 338 L

Table 2. Parameters of the islands that belong to the Primary Island Set 

[L, review of scientific publications, government reports and maps, atlases, and geographic gazetteers; N1, definitions or concepts developed in the 

study; N2, established formulas, algorithms, and logical operations; N3, personal communication of colleagues; ID, identification.]

Count

Parameter descriptions Islands

covered

Information 

source Cumulative Category

—Continued
10 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

86 11 Type of principal center 750 L, N1

87 12 Latitude of principal center 690 L, N2

88 13 Longitude of principal center 690 L, N2

89 14 Concentration of an island’s population at the principal center 323 L

90 15 Code that indicates whether or not the island has a port 1,000 L

91 16 Name of principal port 1,000 L

92 17 Latitude of principal port 998 L

93 18 Longitude of principal port 998 L

94 19 Code that indicates whether or not customs may be cleared at 

principal port

835 L

95 20 Type of principal port 998 L

96 21 Size of principal port 998 L

97 22 Code that indicates whether or not an island has a principal airport 1,000 L

98 23 Name of principal airport 1,000 L

99 24 Code letters that identify principal airport 980 L

100 25 Latitude of principal airport 808 L

101 26 Longitude of principal airport 808 L

102 27 Code that indicates whether or not customs may be cleared at 

principal airport

1,000 L

103 28 Elevation of principal airport 767 L

104 29 Length of longest runway at principal airport 793 L

105 30 International time zone at island 1,000 L

Environmental

106 1 Code that indicates types of meteorologic information on an island 1,000 L

107 2 Elevation of station for recording precipitation on an island 184 L

108 3 Length of precipitation record at the station 224 L

109 4 Mean annual precipitation at the station 418 L

110 5 Elevation of station for recording temperature on an island 237 L

111 6 Length of temperature record at the station 243 L

112 7 Annual mean temperature at the station 331 L

113 8 Presence or absence of mangroves on an island 690 L, N2

114 9 Presence or absence of coral reefs at an island 979 L, N3

115 10 Presence or absence of tropical peat on an island 995 L, N3

Table 2. Parameters of the islands that belong to the Primary Island Set 

[L, review of scientific publications, government reports and maps, atlases, and geographic gazetteers; N1, definitions or concepts developed in the 

study; N2, established formulas, algorithms, and logical operations; N3, personal communication of colleagues; ID, identification.]

Count

Parameter descriptions Islands

covered

Information 

source Cumulative Category

—Continued
Primary Island Set 11

The primary coverage of the islands in terms of primary information sources are given in table 3. From 

table 3, the following is noted:

• The grand coverage over all information 

sources over all categories exceeds 102,000, and 

correspondingly, the grand average island coverage per parameter exceeds 840 islands;

• The alphanumeric values for more than one-half 

of the 122 parameters are based on information 

source L, and correspondingly, about one-half of 

the cells that contain either alphanumeric values or 

the symbol “†” are accounted for by the L-based 

parameter values;

• Relative to the information sources, the smallest 

average coverage occurs with the N3-based parameter values and the largest average coverage, with 

the N1-based parameter values, and

• Relative to the categories, the smallest average 

coverage occurs with the Environmental parameters and the largest average coverage, with the 

Identification, Geographic, and Geologic parameters — values for 14 of the 15 Geologic parameters are N1-based. 

Descriptions of the 122 parameters and more 

detailed accounts of their island coverages follow. 

Accompanying maps are in reference to only the Primary Island Set.

116 11 Presence or absence of palms on an island 984 L, N3

117 12 Presence or absence of seasonal snow/ice on an island 948 N3

118 13 Presence or absence of sphagnum peat on an island 953 N3

119 14 Presence or absence of permafrost on an island 981 N3

120 15 Presence or absence of permanent snow/ice on an island 989 N3

121 16 Classification of island glaciation 963 N1

122 17 Hydrologic class that marks general degree of wetness/dryness 

of an island

648 N1

Table 2. Parameters of the islands that belong to the Primary Island Set 

[L, review of scientific publications, government reports and maps, atlases, and geographic gazetteers; N1, definitions or concepts developed in the 

study; N2, established formulas, algorithms, and logical operations; N3, personal communication of colleagues; ID, identification.]

Count

Parameter descriptions Islands

covered

Information 

source Cumulative Category

Table 3. Parameter coverages of islands by 

information source and category 

[L, review of scientific publications, government reports and maps, 

atlases, and geographic gazetteers; N1,definitions or concepts developed 

in the study; N2, established formulas, algorithms, and logical operations; N3, personal communication of colleagues.] 

Parameter 

cluster Parameters

Coverage

Total Average

Primary information source

L 67 53,933 805

N1 26 25,301 973

N2 20 16,565 828

N3 9 7,113 790

 All sources 122 102,912 844

Category

Identification 2 2,000 1,000

Historical 8 6,766 846

Geographic 22 22,000 1,000

Physiographic 19 13,425 707

Geologic 15 15,000 1,000

Hydrologic 9 7,113 790

Economic 30 24,830 828

Environmental 17 11,778 693

 All categories 122 102,912 844

—Continued
12 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Identification Parameters

The islands are identified by two parameters — 

a specific name and a specific number.

The names of the islands are the official names 

reported by the U.S. Board on Geographic Names. Diacritical marks, where appropriate, are retained in the 

spelling of the names. For those islands where two or 

more nations have sovereignty over parts of the islands, 

the conventional names reported by the U.S. Board on 

Geographic Names of the islands are given.

The islands also are identified by specific numbers that effectively substitute for the names of the 

islands. The numbers, which are referred to as “identification (ID) numbers,” range from 1 through 1,000. 

The particular number assigned to an island corresponds to the order number along the geophysically 

based sequential arrangement of the 1,000 islands 

referred to as the “Alisida” (Alisida being the English 

transliteration of the Greek word, αλυσιδα, for chain) 

which is a benchmark arrangement of the islands 

against which other sequential arrangements of the 

islands may be compared.

The 1,000 islands of the Primary Island Set may 

be ordered in several ways; each arrangement is 

referred to as an “island chain.” For general reference 

purposes, the most useful ordering, perhaps, is alphabetic. For some scientific purposes, however, an ordering that reflects a high degree of geophysical coherence 

is apt to be more useful. An island chain is not unique 

because various factors that relate to the islands (for 

example, location, geologic setting, geologic type, 

island grouping, and chain length) may be given different degrees of importance. It is difficult to design a 

search for an optimum chain as a straight forward procedure like that for finding the extreme values of a 

function. The search for an optimum geophysical chain 

entails scientific judgment in balancing the relative 

importance of the various factors governing the topology of the chain.

A particular island chain was found to have special significance. The particular chain, which has been 

developed through an extensive trial and error procedure, serves as a benchmark for assessing the geophysical significance of other island chains. The procedure 

used to develop this chain consisted of testing numerous chain variations in terms of the trade-off between 

enhancement of the geologic compactness of the chain 

(that is, track continuity on continental margins and on 

major features of the ocean floor) and increases in the 

physical length of the chain. The aim was to achieve a 

high degree of geologic coherence while maintaining a 

minimal chain length under the following constraints:

• The chain passes once and only once through each 

region and subregion in which the Earth’s oceanic 

surface is partitioned;

• The number of times the chain loops over itself 

and crosses a continent are both minimal;

• In the case of an archipelago that reveals little in 

the way of geologic structure, the chain tracks 

through the archipelago on a nearest-neighbor 

basis, such that the last island in the archipelago is 

the nearest neighbor to the first island in the next 

archipelago, nearness being subjectively judged, 

and

• In the case of an archipelago that exhibits a welldefined geologic trend (for example, a chain of 

aligned mountains or multiple structures that comprise a unique physiographic feature, such as segments of inner and outer island arcs) the chain 

tracks along the trends and structures sequentially.

A general description of the topology of the 

Alisida as an open chain, which begins with one island 

and ends with another, over the surface of the Earth is 

as follows:

1. The Alisida begins with the island Åland (ID–1) 

near the entrance to the Gulf of Bothnia at the 

eastern end of the Baltic Sea;

2. It passes through the Baltic Sea and the English 

Channel to the island Berlenga (ID–26) off the 

west coast of Portugal in the North Atlantic Ocean 

east of the Mid-Atlantic Ridge and then northward 

— tracking 36 islands — to Eysturoy (ID–62), one 

of the Faroe Islands;

3. It then passes eastward around the rim of the Arctic Ocean — tracking 54 islands — to the Icelandic island Heimaey (ID–116) and then reenters the 

North Atlantic Ocean west of the Mid-Atlantic 

Ridge;

4. It then passes southward along the Atlantic margin 

of North America — tracking 12 islands — to the 

island Bermuda (ID–128);

5. It then passes to the southern margin of the 

Bahama Banks, after which it passes northwest-
Primary Island Set 13

ward through the Banks — tracking 5 islands — 

where it reaches the island Great Inagua (ID–133);

6. It continues through the Bahama Banks and then 

passes westward through the Straits of Florida — 

tracking 17 islands — to the island Garden Key 

(ID–150);

7. It then loops through the Gulf of Mexico and the 

Caribbean Basin — tracking 59 islands — to the 

island Barbados (ID–209), after which it passes 

southward along the Atlantic margin of South 

America — tracking 8 islands — to the Falkland 

Plateau;

8. It then crosses the Atlantic–Indian Ridge and 

passes northward in the Atlantic Ocean — tracking 7 islands — where, near the southern margin 

of the Gulf of Guinea, it reaches the island Pagulu 

(ID–224);

9. It then continues northward — tracking 25 islands 

— to the island Porto Santo (ID–249) in the 

Madeira Islands, after which it passes westward to 

the island Flores (ID–250) in the Azores Archipelago near the crest of the Mid-Atlantic Ridge and 

then eastward, passing through the Strait of 

Gibraltar into the Mediterranean Basin — tracking 

9 islands — to the island Alborán (ID–259);

10. It then passes eastward through the Mediterranean 

Basin — tracking 83 islands — to the island 

Cyprus (ID–342), after which it crosses the northern part of the Arabian Peninsula and then passes 

down the Persian Gulf — tracking 2 islands — to 

the island Qeshm (ID–344);

11. It then enters the Indian Ocean and passes southwestward to the Crozet Plateau — tracking 33 

islands — where it reaches the island Possession 

(ID–377);

12. It then passes eastward to the Kerguelen Ridge — 

tracking 2 islands — to the island Heard (ID–

379), after which it passes northward to the upper 

end of the Maldive–Laccadive Ridge — tracking 

13 islands — to the island Chelat (ID–392) and 

then southeastward to the eastern edge of Christmas Rise — tracking 3 islands — to the island 

Christmas (ID–395);

13. It then passes in a counterclockwise manner 

around the continental margin of Australia 

through the Torres Strait and the Arafura Sea — 

tracking 17 islands — to the island Trangan (ID–

412) in the Aru Archipelago;

14. It then passes through the Sunda–Banda Shelf 

along the various arcs, sequentially — tracking 54 

islands — where, on the outer arc of the Indonesian archipelago, it reaches the island Pagi-Seletan 

(ID–466);

15. It continues along the outer arc of the Indonesian 

Archipelago, after which it passes along the Andaman–Nicobar Ridge — tracking 15 islands — to 

the island North Andaman (ID–481);

16. It then passes through the Western Andaman Sea 

— tracking 2 islands — to the island Narcondam 

(ID–483), after which it passes northward into the 

Bay of Bengal to the island Cheduba (ID–484) off 

the coast of Burma;

17. It then passes along the western coast of the Malay 

Peninsula — tracking 5 islands — to the island 

Singapore (ID–489), after which it loops through 

the Gulf of Thailand and the South China Sea — 

tracking 13 islands — to the island Spratly (ID–

502);

18. It then passes northward through the Philippine 

Archipelago — tracking 33 islands — to the 

island Itbayat (ID–535) in the Batan Islands, after 

which it passes along the Pacific margin of Asia — 

tracking 8 islands — to the island Taiwan (ID–

543);

19. It then passes through the Ryukyu Islands (Nansei 

Shoto) — tracking 15 islands — to Tanega Sima 

(ID–558), after which it passes through the Korea 

Strait — tracking 5 islands — to the island Ullung 

Do (ID–563) off the coast of South Korea in the 

Sea of Japan;

20. It then passes through the Japan Archipelago — 

tracking 15 islands — to the island Rebun To (ID–

578), after which it passes around the Sea of 

Okhotsk — tracking 2 islands — to the island 

Suyatoy Iony (ID–580);

21. It then passes along the Kuril Trench — tracking 9 

islands — to the island Shumshu (ID–589) after 

which it passes northward into the Bering Sea to 

the island Karaginskiy (ID–590) off the Siberian 

coast;

22. It then loops through the Bering Sea — tracking 

28 islands — where, along the Aleutian Trench, it 

reaches the island Montague (ID–618);
14 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

23. It continues along the Aleutian Trench and then 

passes southward along the Pacific margins of 

North and South America — tracking 44 islands 

— to the island Tierra del Fuego (ID–662), after 

which it passes along the South Sandwich Trench, 

the Scotia Ridge, and the Pacific margin of Antarctica to Macquarie Ridge — tracking 29 islands 

— to the island Macquaire (ID–691);

24. It then passes northward along Lord Howe Rise to 

the southern margin of the Coral Sea and then 

southward along the Norfolk Island Ridge — 

tracking 9 islands — where it reaches the island 

Campbell (ID–706);

25. It then passes northward along the Kermadec and 

the Tonga Trenches to the Fiji Archipelago — 

tracking 46 islands —to the island Kadavu (ID–

752);

26. It then passes around the Hunter, the New 

Hebrides, and the Solomon Ridges, after which it 

loops around the Bismarck Sea — tracking 60 

islands — to the island Unea (ID–812), one of the 

Witu Islands of Papua New Guinea;

27. It then passes westward to the West Caroline 

Basin, after which it passes northward along the 

Yap Ridge and the Mariana and the Bonin 

Trenches — tracking 45 islands — to 

O Shima (ID–867), in the Nampo Shoto (archipelago);

28. It then passes westward into the broad expanse of 

the Mid-Pacific Basin — tracking 24 islands — 

where, in the Marshall Islands, it reaches the 

island Bikini (ID–889); 

29. It then continues eastward in the Mid-Pacific 

Basin through the various archipelagos and isolated islands in a sequential manner — tracking 89 

islands — to the island of Hawaii (ID–978);

30. It then passes eastward into the eastern sector of 

the Pacific Ocean — tracking 6 islands — where it 

reaches the island Cocos (ID–984);

31. It then passes southward through the eastern sector of the Pacific Ocean — tracking 16 islands — 

where, near the junction of the East Pacific Ridge 

and the Easter Island Fracture Zone, the Chain 

ends at the island Pascua [Easter Island (ID–

1,000)].

The general track of the Alisida is depicted in 

figure 4. A more detailed depiction is given in Appendix F and on Plate 1.

The identification numbers linked to the Alisida 

uniquely identify the islands, in contrast to the island 

names. Duplicate names are associated with 37 of the 

1,000 islands (table 4).

The islands named Montague (ID–618) and 

Montagu (ID–669) have been included among the list 

of duplicate island names though the spellings of the 

islands’ names differ only in terms of the inclusion and 

exclusion of the letter “e,” respectively. Had the 

English language names of the islands been given São 

Paulo (ID–210), which is Portuguese for Saint Paul and 

is located in the Atlantic Ocean off the coast of Brazil, 

would have been included in the list of duplicate island 

names.

Historical Parameters

The social history of islands is only tangential to 

a study of the geology and hydrology of islands in relation to current environmental issues; for example, climate change and related rises in sea level, population 

growth, and sustainable economic development. Nonetheless, the study of islands within any context is difficult without touching upon their histories, at least in 

reference to their first European contacts. Vestiges of 

those contacts remain that bear on the current geopolitical setting of the islands that, in turn, bear upon the 

potential future economic development of the islands. 

Thus, a cursory view through eight parameters is taken 

of the first European contacts with the islands.

The eight historical parameters may be partitioned into the following sets:

• Those that provide details about the first European 

contacts with specific islands, and

• Those of names, other than the official names, of 

the islands.

First European Contact

An historical account of the first European contacts with islands is limited to contacts established after 

AD. 1400. Islands on the continental margins of Africa 

and Eurasia, except along the northern rim of Eurasia, 
Primary Island Set 15 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Island identification numbers

1 to 100101 to 200201 to 300301 to 400401 to 500

501 to 600601 to 700701 to 800801 to 900901 to 1,000

Figure 4. Track of the Alisida per 100 island segments.
16 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Table 4. Duplicate island names

Count

Island

Name Identification parameter (ID) General location

1 Andros 146 Atlantic Ocean — Bahama Islands

2 " 321 Mediterranean Basin — Aegean Islands

3 Bathurst 102 Arctic Ocean — Canadian Arctic Archipelago

4 " 411 Indian Ocean — off the northwest coast of Australia

5 Camiguin 507 Pacific Ocean —southern part of Philippine Islands

6 " 531 Pacific Ocean — northern part of Philippine Islands

7 Clarence 655 Pacific Ocean — off the coast of Chile

8 " 675 Pacific / Atlantic Oceans — between South America and Antarctica

9 Flores 250 Atlantic Ocean — Azores

10 " 452 Pacific Ocean — Indonesian Islands

11 Graciosa 246 Atlantic Ocean — Canary Islands

12 " 255 Atlantic Ocean — Azores

13 Long 126 Atlantic Ocean — off the coast of United States (New York)

14 " 138 Atlantic Ocean — Bahama Islands

15 " 816 Pacific Ocean — off the northeast coast of New Guinea

16 Mainland 51 Atlantic Ocean — Orkney Islands

17 " 55 Atlantic Ocean — Shetland Islands

18 Melville 105 Arctic Ocean — Canadian Arctic Archipelago

19 " 410 Indian Ocean — off the northwest coast of Australia

20 Montague 618 Pacific Ocean — off the south coast of Alaska

21 Montagu 669 Pacific / Atlantic Oceans — between South America and Antarctica

22 North 362 Indian Ocean — Seychelles Islands

23 " 701 Pacific Ocean — New Zealand Archipelago

24 Prince Edward 121 Atlantic Ocean — off the coast of Nova Scotia

25 " 374 Indian Ocean — Prince Edward Islands

26 Prince of Wales 108 Arctic Ocean — Canadian Arctic Archipelago

27 " 407 Indian / Pacific Oceans — off the north coast of Australia

28 " 621 Pacific Ocean — off the southwest coast of Alaska

29 Saint Paul 380 Indian Ocean 

30 " 594 Pacific Ocean — Bering Sea

31 San Cristobal 777 Pacific Ocean — Solomon Islands

32 " 992 Pacific Ocean — Galapagos Islands

33 Santa Cruz 629 Pacific Ocean — off the west coast of California

34 " 991 Pacific Ocean — Galapagos Islands

35 South 355 Indian Ocean — Aldabra Atoll

36 " 360 Indian Ocean — Seychelles Islands (Farquhar Group)

37 " 702 Pacific Ocean — New Zealand Archipelago
Primary Island Set 17

were considered to be outside the domain of contact. 

Four archipelagos also were considered to be outside 

the domain of first contact — the Canary Islands off 

the northwest coast of Africa, the Philippine Islands 

and the Japanese Islands in the western Pacific Ocean, 

and the Malay Archipelago, which extends along the 

margin of the Indian and the Pacific Oceans from the 

Malay Peninsula eastward to the large island of New 

Guinea (ID–820). Most of the islands inside the contact domain are located in the Caribbean Basin, the 

Pacific Ocean, and the north and south polar regions.

Of the 1,000 islands:

• 629 are coded as “Y” to indicate that they are 

inside the domain of contact, and

• 371 (the balance of 1,000-629) are coded as “N” 

to indicate otherwise (figure 5).

For many of the islands, particularly those in the 

Pacific Ocean, historians are not in agreement as to 

when the first European contact was established and as 

to who established that contact. In the case of the 

Pacific islands, information about first European contact in terms of the year contact was made, the captain 

of the European expedition that established that contact, the name given to the island following first 

contact, and the nation that sponsored the expedition 

follows Sharp’s (1985) account of “firm evidence” 

of first contact. Enhancement of historical agreement 

regarding the first European contact is outside the 

scope of this study. 

Of the 629 islands inside the domain of first contact:

• The year of first contact is given for 379 of the 

islands;

• The name of the captain of the expedition that 

made that first contact, for 378 of the islands;

• The name given to the island following first contact, for 149 of the islands, and

• Sponsorship of the expedition that made first contact, for 376 of the islands. 

A global perspective on the temporal distribution 

of first European contact with islands is shown in figure 

6.

To each of these island counts, the value 371 

must be added to obtain the island coverages of the 

parameters noted in table 2 — 371 being the number of 

islands that are outside the domain of first contact, and, 

therefore, the islands for which specific values of the 

parameters are not applicable (†). Sponsorships of the 

expeditions that made first contact with the islands that 

are accounted for in this study are American (AM), 

British (BR), Canadian (CA), Dutch (DU), French 

(FR), Norwegian (NO), Portuguese (PO), Russian 

(RU), and Spanish (SP).

A general account of the islands by expedition 

sponsorship is shown in figure 7.

 Other Names of the Islands

Over time, many of the island names and their 

spellings have undergone a number of changes as geographers, cartographers, and others sought to draw a 

more exacting picture of the Earth’s surface and as the 

jurisdiction over islands changed hands. Many of the 

older names are corruptions of native names adopted 

by early explorers that have found their way into western literature. Where name changes have been most 

prevalent is within the Pacific region. For a very extensive list of alternate/former names of Pacific islands, 

see Motteler (1986).

In recent years, some of the newly emerged 

island nations have renamed their islands to reflect 

their own language and culture. For example, the 

islands of Mwali, Njazidja and Nzwani, which form the 

sovereign state of the Comoros Islands, were formerly 

named Moheli, Grande Comore, and Anjouan. For 

many other islands, their names have remained 

unchanged for centuries, and to ascertain if those 

islands were once known by other names is difficult.

To facilitate the search of the literature, particularly the older literature, other names of the islands, 

beside the official names, are given. Collectively, the 

names are coded to indicate that the names are of one 

of the following classes of names:

• Official name as reported by the U.S. Board on 

Geographic Names — coded “ON”;

• Conventional name as reported by the U.S. Board 

on Geographic Names — coded “CN”;

• Historical name; that is, the name given or 

adopted following first European contact — coded 

“HN,” and

• Former name; that is, name other than official, 

conventional or historical, an island acquired over 

time — coded “FN.”
18 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Islands inside domainIslands outside domain

Figure 5. Extent of the domain of first European contact.
Primary Island Set 19 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Year of first European contact

1400 to 14491450 to 14991500 to 15491550 to 15991600 to 1649

Outside domain

1650 to 16991700 to 17491750 to 17991800 or laterDate uncertain

Figure 6. Global perspective on the temporal distribution of first European contact with islands.
20 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Sponsorship of expedition

AmericanBritishCanadianDutchFrench

NorwegianPortugueseRussianSpanishUnspeicified

Outside domain

Figure 7. Global distribution of first European contact with islands per sponsorship of expedition.
Primary Island Set 21

For example, Pascua (Spanish for Easter; more 

appropriately, Isla de Pascua) is the official name of the 

island with the ID number 1,000. When Jacob Roggeveen, who was captain of a Dutch expedition, sighted the 

island, the first European to do so, on Easter morning, 

April 15, 1722, he named the island Paasch Eylandt 

(Dutch for Easter Island), which is the historical name 

of the island. The conventional name of the island is 

Easter Island.

In addition to the 1,000 official names of the 

1,000 islands, there are:

• 37 islands with conventional names,

• 149 islands with historical names, and

• 326 islands with former names.

Each of the 326 islands with former names has at 

most 7 alternate names, such that the total number of 

former names for these islands is 987. Combining the 

four classes of names, the total number of names associated with the 1,000 islands of the Primary Island Set 

amounts to 2,173 (= 1,000 + 37 + 149 + 987).

Inforamtion, mainly historical, that does not lend 

itself to a spreadsheet presentation is given in Appendix 

K for 281 of the 1,000 islands belonging to the primary 

island set.

Summary

The island coverages by the eight historic parameters are summarized in table 5.

Geographic Parameters

A map of the world reveals that the saltwater 

islands are not uniformly distributed, even in a statistical sense, over the Earth’s oceanic surface. Most of the 

islands are concentrated in the Pacific Ocean, more 

specifically in the western Pacific Ocean. A description 

and explanation of the distribution of the islands is 

important in addressing a number of diverse questions 

concerning such matters as follow:

• The Earth’s geologic history,

• Dispersion and concentration of terrestrial plant 

and fauna species within the oceanic environment,

• Communication and trade between continental 

and island nations, and

• Development of an island’s resources within the 

bounds of the island’s exclusive economic zone.

Herein, the distribution of the world’s islands is 

viewed through the distribution of the 1,000 islands in 

the Primary Island Set, the distribution being described 

by the 22 Geographic parameters specified in table 2. 

The parameters may be partitioned into the following 

groups:

Table 5. Island coverage, by historical parameter

Islands

Parameter Specified

A

Inapplicable

B

Covered

A+B

Unspecified

C

Total

A+B+C

Contact index 1,000 0 1,000 0 1,000

Year of earliest contact 379 371 750 250 1,000

Captain of expedition 378 371 749 251 1,000

Expedition sponsorship 376 371 747 253 1,000

Name given to island 

 following earliest contact

149 371 520 480 1,000

Conventional name 1,000 0 1,000 0 1,000

Other names 308 0 1,000 692 1,000

Island name code 1,000 0 1,000 0 1,000
22 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

• Those that provide specific locations of the islands 

on the Earth’s surface and general locations of the 

islands among themselves;

• Those that identify affinities between the islands, 

and

• Those that relate to topologic properties of the 

islands defined in terms of distances between one 

island and another.

Locations of Islands

The location of an island on the Earth’s surface 

is uniquely specified by the values of its geographic 

coordinates — latitude and longitude. Herein, the coordinate values are reported to the nearest hundredth 

degree with positive (negative) values denoting latitudes north (south) of the equator and longitudes east 

(west) of Greenwich. These values are decimal degree 

equivalents of the values given by the U.S. Board on 

Geographic Names that are expressed to the nearest 

minute with the values designated as N (S) which 

denote latitudes north (south) of the equator, and values 

designated as E (W) which denote longitudes east 

(west) of Greenwich. The values given by the U.S 

Board on Geographic Names refer to points on geographically scaled maps of the islands that are judged 

to be at or near the geometric centers of the islands; that 

is, the centers of gravity of the areas of the islands. 

Refer to Appendix A.

The geographic coordinates are specified for 

each of the 1,000 islands.

The location of an island is further specified by 

its oceanic setting. Herein the oceanic surface of the 

Earth is partitioned into six regions, as shown in table 

6. The boundaries of the regions are depicted in figure 

8.

The six oceanic regions are divided into 32 subregions, which form natural provinces of the oceans as 

delineated by major topographic features of the ocean 

floor and the continental margins, as shown in table 7. 

The oceanic regions and the oceanic subregions for the 

1,000 islands are specified.

Table 6. Oceanic regions

Count Region Description

1 Greater Atlantic Ocean Encompasses the Atlantic and the Arctic Oceans 

which includes their adjacent seas.

2 Mediterranean Basin Remnant of a once much-larger expanse of water, 

Tethys, that was connected with the modern Atlantic Ocean by way of the Strait of Gibraltar. Its connection with the modern Indian Ocean is now 

separated by the Arabian Peninsula and its northern 

extension.

3 Indian Ocean Encompasses the Indian Ocean, which includes all 

adjacent seas, except those along the eastern 

margin of the Ocean.

4 Sub-Australia Encompasses the waters over the Continental Shelf 

of Australia.

5 Sunda–Banda Encompasses the waters over the relatively shallow 

extension of the Continental Shelf of Southeast 

Asia and the sea adjacent to the eastern margin of 

the Indian Ocean.

6 Pacific Ocean Encompasses all the oceanic waters not encompassed by the other five regions. 
Primary Island Set 23

G R E A T E R A T L A N T I C O C E A N

I N D I A N

O C E A N

P A C I F I C

O C E A N

P A C I F I C

O C E A N

G R E A T E R

A T L A N T I C

O C E A N

G R E A T E R

A T L A N T I C

O C E A N

Mediterranean

Basin

Sub-Australia

Sunda

Banda

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Oceanic region boundary

Figure 8. Boundaries of oceanic regions.
24 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Table 7. Oceanic subregions

Count Subregion General bounds of subregion

Greater Atlantic Ocean

1 Baltic Sea East of Skagerrak

2 Northeastern Sector Above triple junction of North American, Eurasian, and African 

Lithospheric Plates; East of Mid-Atlantic Ridge

3 Sub-Arctic Rim Arctic Ocean and adjacent seas

4 Northwestern Sector North of Equator; West of Mid-Atlantic Ridge

5 Caribbean Basin Caribbean Sea

6 Southeastern Sector South of Equator; East of Mid-Atlantic Ridge

7 Southwestern Sector Below triple junction of North American, Eurasian, and African 

Lithospheric Plates; West of Mid-Atlantic Ridge

Mediterranean Basin

8 Western Sector West of Malta Channel

9 Eastern Sector East of Malta Channel

Indian Ocean

10 Western Sector West of Southwest Indian and Carlsberg Ridges

11 Southern Sector South of Southwest Indian and Mid-Indian Ridges

12 Eastern Sector East of Carlsberg and Mid-Indian Ridges

Sub-Australia

13 Western Sector Western Continental Shelf of Australia

14 Southern Sector Southern Continental Shelf of Australia

15 Eastern Sector Eastern Continental Shelf of Australia

16 Northern Sector Northern Continental Shelf of Australia

Sunda–Banda

17 Halmahera Sector Seram, Halmahera, and Molucca Seas

18 Sulawesi Sector Flores and Molucca Seas; Makassar Strait

19 Outer Bunda Arc Seram and Banda Seas

20 Inner Bunda Arc Along southern margin of Banda, Flores, and Java Seas; Selat 

Mentawani and Strait of Malacca

21 Inner Sunda Arc Andaman, Java, Flores, and Banda Seas

22 Outer Sunda Arc Along Andaman – Java Trench

23 Andaman Sea Andaman Sea

24 Malay Trend Along emerged and submerged Malay Peninsula

25 Borneo Sector Selat Karimata; northern margin of Java Sea; Makassar Strait

Pacific Ocean

26 Northwestern Rim South and East China Seas; Seas of Japan and Okhotsk

27 Northern Rim Aleutian Trench; Bering Sea

28 Eastern Rim East of Queen Charlotte and Cascade Faults; Mid-America– Peru – 

Chile Trenches; Scotia Basin; off Grahamland
Primary Island Set 25

Island Affinities

Each island is presumed to be a member of an 

island group that forms a more or less distinct island 

cluster. An island group may consist of the following:

• A single island and nothing more than off-shore 

rocks, the number and the areas of which vary 

with the tide; for example, Newfoundland (ID–

117);

• Several islands comparable in area; for example, 

the Bahamas (ID–133, ..., ID–146), or

• A few islands that make up the greater share of the 

total area of the islands in the group; for example, 

the Fiji Islands (ID–731, ..., ID–752).

If an island is part of an island group that is commonly referred to by a specific name in the geographic 

literature, then the island is coded as 0, and the island 

group name is associated with the island. In reference 

to a particular island, if the literature gave no indication 

that the island is a member of a named island group, 

then the island is coded as 1, and the island is assumed 

to “belong” to a group that bears the island’s name. 

Some particular island groups named in the literature 

that are taken into account in the study do not accord 

with a strict geographic hierarchical clustering of 

islands. For example, the four island groups — Greater 

Sunda, Lesser Sunda, Northern Moluccas, and Southern Moluccas — considered herein collectively form 

the geographically specified Malay Archipelago, 

which extends from the Malay Peninsula eastward to 

the large island of New Guinea (ID–820). The Japanese 

Archipelago is considered to include the four large Japanese islands — Kyushu (ID–571), Shikoku (ID–572), 

Honshu (ID–574), and Hokkaido (ID–576) — and the 

relatively small islands that lie within a few kilometers 

from their shores.

The 1,000 islands are partitioned into 299 island 

groups, where: 

• The names of 137 island groups — official names 

or, if applicable, conventional names reported by 

the U.S. Board on Geographic Names — which 

account for 838 islands, are derived from the literature, and

• The names of the remaining 162 (= 299 – 137) 

island groups, which account for the remaining 

162 (= 1,000 – 838) islands, are the same as those 

of the single islands that make up these groups.

The island group to which an island belongs is 

noted not only by the name of the island group, but also 

by the island group’s identification number that corresponds to the order number of the first occurrence 

along the track of the Alisida of an island that belongs 

to the island group. Thus, the island of Åland (ID–1) is 

identified as belonging to the Ahvenanmaa Islands 

(ID–1), and the island of Pascua (ID–1,000) is identified as belonging to the “Pascua Islands” (ID–299) — 

Pascua is generally thought of as an isolated island.

Within an island group that consists of two or 

more islands, the names of the island subgroups to 

which the islands belong are given if the subgroup 

names were found in the geographic literature — official or, if applicable, conventional names reported by 

the U.S. Board on Geographic Names. Names were 

found for 125 subgroups, which account for 363 of the 

1,000 islands. In the case where no subgroup name was 

found in the literature, no subgroup name was imposed. 

The subgroup names are not used as a basis for further 

description of the islands and therefore the remaining 

637(=1,000-363) islands were presumed not to be part 

of any island subgroup.

29 Southwestern Rim Macquarie Ridge; Chatham – Campbell Plateau; Lord Howe Rise; 

Fiji, New Hebrides, Santa Cruz, and Solomon Basins; Bismarck 

Sea.

30 Western Sector Along Belau, Yap, Mariana, and Japan Trenches

31 Central Sector East of Belau– Mariana and Kermadec –Tonga Trenches ; south of 

Aleutian Trench; west of Pacific Rise

31 Eastern Sector East of Pacific Rise; Peru– Chile Trench

Table 7. Oceanic subregions

Count Subregion General bounds of subregion

—Continued
26 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Topologic Properties of the Islands

The topologic properties of the islands are 

defined in terms of the distances between one island 

and another. All distances, which are measured in kilometers (km), between specific points on the Earth’s 

surface are determined as great circle distances for a 

spherical Earth with a radius of 6,370.997 km, whereby 

the equatorial circumference is 40,030 km. Refer to 

Appendix A.

Two distances between one island and another 

were considered:

• Positional distance — the great circle distance 

between the points on the Earth’s surface marked 

by the geographic coordinates of the islands, and

• Virtual distance — the positional distance minus 

the sum of the radii of the islands, assuming they 

were shaped as circles.

The virtual distance approximates the minimum 

coast-to-coast distance between two islands.

The Alisida passes only once through each of the 

six regions into which the Earth’s oceanic surface has 

been partitioned, it never crosses itself, and only once, 

in passing from the Mediterranean Basin to the Persian 

Gulf, does it cross a continental “barrier.” The length of 

the Alisida, which is equivalently the sum of the interisland positional distances from Åland (ID–1) to Pascua (ID–1,000) is 329,251 km. Along the track of the 

Alisida, the following “milestones” are reached (figure 

9):

1. Great Exuma (ID–139) marks the Alisida’s length 

at 40,021 km, which is equivalent to about one 

circumference of the Earth;

2. Principe (ID–226) marks the Alisida’s length at 

79,984 km, which is equivalent to about two circumferences of the Earth;

3. Possession (ID–377) marks the Alisida’s length at 

119,412 km, which is equivalent to about three 

circumferences of the Earth;

4. Tanahmasa (ID–471) marks the Alisida’s length at 

160,035 km, which is equivalent to about four circumferences of the Earth;

5. Chichagof (ID–619) marks the Alisida’s length at 

200,426 km, which is equivalent to about five circumferences of the Earth;

6. Antipodes (ID–707) marks the Alisida’s length at 

240,190 km, which is equivalent to about six circumferences of the Earth;

7. Mejit (ID–892) marks the Alisida’s length at 

280,210 km, which is equivalent to about seven 

circumference of the Earth;

8. Cocos (ID–984) marks the Alisida’s length at 

320,020 km, which is equivalent to about eight 

circumferences of the Earth, and

9. Pascua (ID–1,000) marks the total length of the 

Alisida at 329,251 km, which is equivalent to 

about eight and one-fourth circumferences of the 

Earth. 

The positional distance between Åland (ID–1) 

and Pascua (ID–1,000) is 14,742 km, which is about 

three-fourths of the distance from any one of the 

islands to its antipode.

The following sets of extremal topologic properties of the islands were considered:

• The name and ID number of the nearest island to a 

specific island as measured by the positional and 

virtual distances between the islands;

• The name and ID number of the farthest island, 

and the oceanic region in which it is located to a 

specific island as measured by the positional distance between the islands, and

• The geographic coordinates of each island’s antipode and the antipode’s ocean or continent location.

The antipode marks the location of a point on the 

Earth’s surface that is diametrically opposite the location of a specific point. For all islands, the positional 

distance between the location of an island, as marked 

by its geographic coordinates, and the location of its 

antipode is 20,015 km (= one-half of the equatorial circumference).The relative locations of the islands and 

their antipodes is shown in figure 10.
Primary Island Set 27 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Number of circumferences

0 to 11 to 22 to 33 to 44 to 5

5 to 66 to 77 to 88 to 8.3

Figure 9. Distance along the track of the Alisida, expressed as equivalent circumferences of the Earth.
28 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

IslandAntipode

Figure 10. Relative locations of the islands and their antipodes.
Primary Island Set 29

Summary

For each of the 22 geographic parameters, the 

island coverages are complete; that is, for each island, 

a specific alpha or numeric value is given for each of 

the 22 parameters. Table 8 lists the condensed parameter descriptions.

Table 8. Island coverage, by geographic parameter

Parameter

Islands

Specified

A

Inapplicable

B

Covered

A+B

Unspecified

C

Total

A+B+C

Location

Latitude 1,000 0 1,000 0 1,000

Longitude 1,000 0 1,000 0 1,000

Oceanic region 1,000 0 1,000 0 1,000

Oceanic subregion 1,000 0 1,000 0 1,000

Association

Island group name 1,000 0 1,000 0 1,000

Code that indicates if island belongs to a 

geographically named island group

1,000 0 1,000 0 1,000

Island group ID (identification) number 1,000 0 1,000 0 1,000

Island subgroup number 1,000 0 1,000 0 1,000

Topology

Interisland positional distance 1,000 0 1,000 0 1,000

Cumulative interisland positional distance 1,000 0 1,000 0 1,000

Name of nearest island to a specific island 1,000 0 1,000 0 1,000

ID (identification) number of nearest island 1,000 0 1,000 0 1,000

Positional distance to nearest island 1,000 0 1,000 0 1,000

Virtual distance to nearest island 1,000 0 1,000 0 1,000

Name of farthest island 1,000 0 1,000 0 1,000

ID (identification) number of farthest island from a 

specific island

1,000 0 1,000 0 1,000

Positional distance to farthest island 1,000 0 1,000 0 1,000

Oceanic region of farthest island 1,000 0 1,000 0 1,000

Latitude of antipode 1,000 0 1,000 0 1,000

Longitude of antipode 1,000 0 1,000 0 1,000

Ocean of antipode 1,000 0 1,000 0 1,000

Continent of antipode 1,000 0 1,000 0 1,000
30 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Physiographic Parameters

Knowledge of the physiographies of islands is 

important to various studies; for example, to determine 

orthographic controls on the distribution of precipitation over islands, variations in island ecological zones 

with elevation, rates of water and sediment discharges 

from islands, history of climate change and associated 

changes in sea levels reflected by islands as evidenced 

by terraces, and crustal movements of the Earth, such 

as local tectonics as evidenced by uplifting and tilting 

of islands.

Herein, the physiographies of the 1,000 islands 

are described by 20 parameters that may be partitioned 

into five groups that provide the following:

• Basic measures of the sizes of the islands;

• Quantitative descriptors of the island groups to 

which the islands belong;

• Qualitative descriptors of island topographies;

• Qualitative descriptors of island shapes, and

• Dimensional measures of islands.

Size of Islands

The basic measures of the size of an island are as 

follows:

• Surface area — measured in units of square kilometers (km2

) in reference to sea level, and

• Elevation of the highest peak — measured in units 

of meters (m) above sea level.

The elevation of the highest peak describes an 

extremal property of an island’s physiography. A more 

representative property is the mean elevation. Unfortunately, estimates of mean elevations have been reported 

for very few islands. For still fewer islands have their 

hypsometries, changes in surface area as a function of 

elevation, been reported (see, for example, Strahler, 

1952).

The values of the island areas and elevations of 

their highest peaks were obtained from the scientific 

literature and from government reports and maps. The 

values of area range over eight orders of magnitude, 

from 0.1 (= 10-1) km2 to 2,175,600 (= 2.1756 x 106

) 

km2

, the upper bound being the area of Grønland (ID–

112). The values of highest elevation range over four 

orders of magnitude, from 5 (= 5 x 100

) m to 5,030 

(= 5.030 x 103

) m, the lower bound being related to several of the islands that have very small areas and the 

upper bound being the highest elevation of New 

Guinea (ID–820).

Global perspectives on the distribution of the 

areas of the islands and on the distributions of the elevations of the highest peaks on the islands are given in 

figures 11 and 12, respectively.

The values of area and elevation of the highest 

peak were assumed to be in reference to a common sea 

level datum. However, the literature is, for the most 

part, ambiguous as to which sea level datum is used for 

the reported values of area and elevation of highest 

peak. Tide gages are located at only a very few islands 

(see, for example, Emery and Aubrey, 1991), thus making it difficult to determine values of area and elevation 

of highest peak for all islands relative to a common sea 

level datum.

For many islands, reported values of area and 

elevation of highest peak differ somewhat among reference sources. In such cases, preference was given to 

those values reported in official government reports. If 

such reports could not be found, then preference was 

given to the values reported in the most current scientific literature unless the “weight of evidence” favored 

some earlier publication. Herein, the values are given 

to the same level of accuracy as reported in the literature, except for the few islands whose areas of less than 

0.1 km2 were rounded up to 0.1 km2

. Values reported in 

the literature in English units were converted to metric 

units of equivalent accuracy.

It should be noted that for the “low” islands, the 

values given for the elevations of the highest peaks may 

not be necessarily the highest values. In the literature, 

many of the low islands were said to be above sea level 

by certain amounts without specifying whether the values were to be interpreted as the highest values or as 

general average values. The literature is much more 

specific regarding “high” islands. 

The area and the elevation of the highest peak are 

given for each of the 1,000 islands. Had one or the 

other or both of these basic measures of island size not 

been determined for a particular island, that island 

would not be part of the Primary Island Set.

For many islands, the highest peaks are 

unnamed, particularly for the “low” islands where the 

peaks, as such, are not very significant physiographic
Primary Island Set 31 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Island area, in square kilometers

10 or less11 to 100101 to 1,000

1,001 to 10,00010,001 to 100,000Greater than 100,000

Figure 11. Global perspective on the distribution of the area of the islands.
32 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Elevation of highest peak, in meters

10 or less11 to 100101 to 500

501 to 1,0001,001 to 2,500Greater than 2,500

Figure 12. Global perspective on the distribution of the elevations of the highest peaks on the islands.
Primary Island Set 33

aspects of the islands. For the purpose of this study, the 

highest peaks of the islands were taken to be unnamed 

if the elevations of the peaks did not exceed 50 m. For 

the 139 islands whose highest peaks do not exceed 50 

m, the names and coordinates of the highest peaks are 

therefore not applicable (†).

Of the 861 (= 1,000 – 139) islands whose highest 

peaks exceed 50 m:

• The names of the highest peaks, which were 

derived from the literature, are given for 552 

islands; and for these islands

• The coordinates, latitude and longitude, of the 

highest peaks are given as decimal degree equivalents of the degree/minute values of the U.S. 

Board on Geographic Names; and

• For 49 additional islands, the coordinates of their 

highest peaks were read from maps; whereby

• The total number of islands for which the coordinate values of their highest peaks are given is 601 

(= 552 + 49).

To each of these island counts, the value 139 

must be added to obtain the island coverages noted in 

table 2 — 139 being the number of islands whose highest peaks do not exceed 50 m and, therefore, the number of islands for which names and coordinates of their 

highest peaks are not applicable (†).

Quantitative Descriptors of Island Groups

Associated with each island are the following 

characteristics of the island group to which the island 

belongs:

• The number of islands of the Primary Island Set, 

in the island group;

• The total land area of the island group; that is, the 

sum of the areas of the islands in the island group, 

and

• The percentage of the island group area represented by the area of the island.

The characteristics, particularly the number of 

islands in an island group, should not be construed as 

estimates that relate to all the islands — those within 

and those outside the Primary Island Set — of the 

island group. To illustrate, the island of Åland is indicated as belonging to an island group that consists of 

one island, whereas the literature suggests the number 

of islands in the island group to be several thousand. 

Qualitative Descriptors of Island Topographies

Topography is a relevant factor in most studies of 

islands. It is important to theoretical analyses of island 

morphology, and in other studies; for example, those 

dealing with local climate, hydrology, geology, vegetation distribution, and economic activity. To facilitate 

quantitative synoptic studies of the islands, a scheme 

for topographically classifying islands in a systematic, 

consistent, and incisive manner was needed. Such a 

scheme could not be found in the literature. The literature does provide descriptions of the geography and 

topographic features of individual islands, but the 

descriptions vary greatly in detail. For some islands, 

the descriptions are seemingly nonexistent. On the 

basis of the topographic information provided by the 

literature and on the depictions of the terrains in maps, 

a scheme was developed for topographically classifying the islands in a uniform manner. 

Considering only primary topographic characteristics, 16 types of island terrains were defined. For a 

given island, the classification scheme entailed the following:

• Identifying the primary topographic units, where a 

unit spans all or a significant portion of the island;

• Identifying the terrain type of each unit;

• Identifying the topological relations between the 

component units terrains, and

• Coding the topographic identifications of the terrain types and compounding the codes by using 

symbolic logic to correspond to the topological 

relations among the terrain units.

The coding is as follows. To each terrain type, a 

code that consists of one of four letters is assigned — 

H, P, T, and N — followed by a number (for example, 

P 3) that denotes the primary topographic feature hill. 

The numbers differentiate among the terrains that share 

general aspects of the terrains represented by a letter. 

Basically,

• The H group denotes terrains that consist of 

roughly horizontal surfaces but with different elevation ranges;
34 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

• The P group denotes positive topographic terrains 

with variations in style and degree of relative elevation;

• The T group denotes terrains that are of a tabular 

nature, and

• The N group denotes negative terrains with variations in style and degree of relative depression.

The global distribution of the islands belonging 

to the various terrain groups is shown in figure 13.

More specifically, the codes are given in table 9.

If an island has only one primary topographic 

unit, then the island’s topographic classification is 

given simply by the appropriate code. If there are several primary topographic units, then the classification is 

given by a compound code formed of the codes of the 

individual units. For a topographically compound 

island, the connection among the component codes is 

defined by symbolic logic. If x and y denote two primary topographic units having the topographic classifications X and Y, respectively, then

• denotes the classification of the union of the 

two units; that is, — to a first approximation, x and y are adjoining nonoverlapping units, 

and

• denotes the classification where y is contained in x; that is, x ⊃ y — to a first approximation, y is surrounded by x.

If an island has several units, x1, x2, ..., xn, each of 

the same terrain type, then X, which is the union of the 

units, , has the classification , abbreviated in 

bold type as X.

X Y ∪

x y ∪

X Y ⊃

xi i=1

n

∪ X

i=1

n

∪

Table 9. Codification of island topographies

Count Name Code Definition

1 Low island H1 An island that has a single terrain unit that is nowhere more than 50 m in elevation

2 Lowland H2 Unit of flat or relatively low relief that is nowhere more than 100 m in elevation 

3 Rolling terrain H3 Unit of rolling terrain with relatively low relief and such that the general elevation is more than 

100 m; for example a plateau

4 Knob P1 Unit that, in profile, appears as a pinnacle or a rounded hill

5 Conical terrain P2 Unit whose topography forms a conical mass

6 Hill P3 Isolated mass of relatively smooth terrain and relief of less than 700 m relative to surrounding 

low areas above which the isolated mass gradually rises

7 Dome P4 Isolated uparched mass shaped; for example, as unbreached anticline(s)

8 Ridge P5 Elongated mass, the general shape of which is like an anticline, that extends over a substantial 

part of the length of the island

9 Hills P6 Unit of high, smooth-surface terrain that rises gradually from the surrounding terrain and with 

relative low relief of less than 700 m with respect to adjoining low areas

10 Blocky P7 Isolated mass with roughly planar lateral boundaries

11 Mountain P8 Rough-surfaced terrain that rises abruptly from surrounding terrain and with relief of more than 

700 m relative to surrounding terrain or sea level.

12 Monocline T1 Mass whose upper surface is planar and is uniformly tilted

13 Tabular terrain T2 Surface appears to consist of stacked horizontal layers that decrease in lateral extent in an 

upward direction, and form in effect shelves

14 Apron T3 Surface is concave-upward, such as a piedmont, abutting against or merging into hilly or mountainous terrain

15 Basinal N1 Surface of unit is depressed relative to surrounding terrain, such as a basin or syncline

16 Valley N2 Terrain forms in effect a valley
Primary Island Set 35 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Terrain group

Horizontal surfaceNegativePositive

TabularUnspecified

Figure 13. Global distribution of islands per terrain group.
36 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

The classification of the topographies of the 

1,000 islands was limited to the identification of no 

more than three primary topographic units per island. 

Availability of information permitted the application of 

the terrain classification scheme to 660 islands. The 

quality of the information was such that classification 

based on 2 topographic units was limited to 100 islands 

and classification based on 3 topographic units was 

limited to 12 islands

Qualitative Descriptors of Island Shapes

The notion of the shape of an island is limited to 

the shape defined by the coastline of an island as represented in a map. This is the shape that is seen from the 

air or space and is most relevant to human activities. 

Several measures of shape have been proposed, none of 

which has proved to be entirely satisfactory. No measure can almost always differentiate in numerical terms 

among all shapes that are visually distinctly different. 

Alternately, shape may be described in qualitative 

terms that may be used to develop a scheme for qualitatively classifying island shapes.

A review of the basic set of maps described 

above, complemented by a review of maps presented in 

scientific reports, suggested a scheme for classifying 

the shapes of islands as being one of 10 generic shapes. 

General descriptions of the generic shapes are given in 

table 10.

In figure 14, schematic representations of the 

generic shapes are shown relative to two islands whose 

shapes reflect, to a first approximation, each of the 10 

generic shapes.

The classification scheme for island shapes parallels that for island topographies. If an island has only 

one primary shape unit, then the island’s shape classification is given simply by the appropriate code number. If there are more than one primary shape unit, then 

the classification is given by a compound code formed 

by the codes of the individual units — the connection 

between the codes being defined by symbolic logic. If 

x and y denote two primary units that have the shape 

classifications X and Y, respectively, then:

• X ∪Y denotes the classification of the union of the 

two units; that is, x ∪y — to a first approximation, 

x and y are adjoining, nonoverlapping units, and

• X ⊃Y denotes the classification where y is contained in x; that is, x ⊃y — to a first approximation, y is superimposed on x.

The shape classification of the 1,000 islands was 

limited to the identification of no more than two primary shape units per island. If the shape of an island is 

dominantly of a single specific type, then the island’s 

“second” shape unit is assigned the shape type value 

zero (0). Of the 1,000 islands, 997 were classified as to 

their shape type, and of these islands, 488 were judged 

to be dominated by a single specific shape type.

The global distribution of the island shapes is 

shown in figure 15.

Table 10. Descriptions of generic shapes

Name Code Definition

Polygonal 1 Contour formed by linear 

segments.

Soft Rounded 2 Contour without sharp edges or 

bends

Elongated 3 Smooth contour with a central axis 

of pronounced length relative to 

the length along any other axis

Calabash 4 Smooth contour with one prominent handle-like extension

Horseshoe 5 Smooth contour shaped like a 

horseshoe

Hourglass 6 Contour with two prominent bulgy 

parts connected by a narrower 

neck

Crazy H 7 Smooth contour with four arms that 

extend from a central body, like 

a distorted letter H

Skeletal 8 Contour witrh central axis or body 

with lateral armlike extensions

Amoebic 9 Contour with smooth fingers that 

extend randomly in several 

directions

Serrated 10 Contour distorted by numerous 

sharp indentations
Primary Island Set 37

GENERIC SHAPE EXAMPLES

1. Polygonal

2. Soft rounded

3. Elongated

4. Calabash

5. Horse shoe

6. Hour glass

7. Crazy H

8. Skeletal

9. Amoebic

10. Serrated

Sicilia (ID 283) Bristol (ID 670)

Bohol (ID 522) Kume (ID 548)

Sao Jorge (ID 254) Maewo (ID 766)

Siau (ID 420) Rendova (ID 785)

Deception (ID 679) Oreor (ID 830)

Matthew (ID 753) Tahiti (ID 930)

Sulawesi (ID 422) Mindanao (ID 508)

Laurie (ID 672) Ngeruktabel (ID 829)

Mainland (ID 51) Krk (ID 290)

East Falkland (ID 217) Afognak (ID 617)

Figure 14. Shape comparison of generic and real islands.
38 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Island shape

PolygonalSoft roundedElongatedCalabash

Horse shoeHour glassCrazy HSkeletal

AmoebicSerratedUnspecified

Figure 15. Global distribution of island shapes.
Primary Island Set 39

Dimensional Measures of Islands

In addition to area, the spatial extent of an island 

may be described in terms of various geometrical properties of an island. Among these properties are those 

that measure:

• The linear extent of an island; 

• The ruggedness of an island’s coastline, and

• The compactness of an island’s shape.

These properties were determined, in part, by 

means of digitalization of map-depicted coastlines 

for 267 of the 1,000 islands, whereby geographic 

coordinates were obtained for sets of points distributed 

along the coastlines of each of the islands. Refer to 

Appendix B.

Two measures, in kilometers, of the linear extent 

of an island are length and width. For many islands 

whose areas are distributed along distinct axes, the 

values of length and width are reported in the literature. 

However, with few exceptions, the literature is not 

specific as to how the values were obtained, where 

along the island the values were determined, and if the 

values take into account the curvature of the Earth’s 

surface, particularly in the case of the large islands. 

Implicitly, length is the longest spatial extent of the 

island. Width is often referred to as being the maximum 

width without stating if it is measured normal to the 

axis of length.

From the literature, values of length and width, 

expressed herein in kilometers, were obtained for 734 

of the 1,000 islands.

The following additional measures, in kilometers, of the linear extent of an island were considered:

• The effective radius is the radius associated with 

the area of an island, assuming that the island is 

shaped as a circle, and

• The radius of gyration is the distance from a reference point to a point where, if the area of an island 

was concentrated, the moment of inertia of the 

concentrated area would equal the moment of 

inertia of the distributed area of the island.

The moment of inertia, which is measured in 

square kilometers, measures the “resistance” of the 

island to rotation by a unit force for an island viewed as 

a rigid two-dimensional plate of unit density.

Of the 1,000 islands:

• The effective radius was determined for each 

island on the basis of the island’s area obtained 

from the literature, and

• The radius of gyration was determined for each of 

the 267 islands whose map-depicted coastlines 

had been digitized.

Refer to Appendix B.

Another linear measure of an island is the 

island’s perimeter, which is measured in kilometers. 

For a given value of area, the more rugged the island’s 

coastline, the longer the island’s perimeter. In the 

above discussion of the shape classification scheme, 

two extreme cases were noted, shapes formed by 

smooth contours and shapes formed by contours distorted by numerous sharp indentations. The variation in 

the forms of the contours between these two extremes 

reflects the degree of ruggedness of the coastline, 

where the degree of ruggedness may be measured by 

the fractal dimension of the coastline. For a smooth 

contour (refer to shape type 2, figure 1, table 12), the 

fractal dimension has the value of 1. The more rugged 

coastline is the more “space filling” coastline, whereby 

the nearer is the coastline’s fractal dimension to the 

value of 2 (refer to shape type 10, figure 1, table 12; 

Mandelbrot, 1975).

The perimeter and the coastline fractal dimension were determined for each of the 267 islands whose 

map-depicted coastlines had been digitized. Refer to 

Appendix B.

The compactness of an island’s shape represents 

the extent to which the island “is as long as it is wide” 

(Richardson, 1961). The following dimensionless measures of compactness of an island were considered:

• Compactness 1, which is the function of the length 

and width of the island;

• Compactness 2, which is the function of the 

perimeter and the area of the island, and 

• Compactness 3, which is the function of the area 

and the moment of inertia of the area of the island.

Each of the three measures of compactness was 

normalized, such that the normalized values lie in the 

range (0,1), where the value 1 attains for a circle, which 

is the most compact shape of a two dimensional object, 

and the value 0 is the limiting value of a very long, nar-
40 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

row object, such as, a very elongated island (refer to 

shape type 3, figure 1, table 10). Refer to Appendix C.

Among the 1,000 islands:

• Values of compactness 1 were determined for each 

of the islands whose values of length and width 

had been obtained from the literature;

• Values of compactness 2 and compactness 3 were 

determined for each of the 267 islands whose 

map-depicted coastlines had been digitized; and of 

these 267 islands,

• 202 are among those whose values of compactness 1 also had been determined.

Summary

The island coverages by the 23 physiographic 

parameters are summarized in table 11.

Table 11. Island coverage, by physiographic parameter

Parameter

Islands

Specified

A

Inapplicable

B

Covered

A+B

Unspecified

C

Total

A+B+C

Basic measure of size

Area 1,000 0 1,000 0 1,000

Elevation of highest peak 1,000 0 1,000 0 1,000

Name of highest peak 552 139 691 309 1,000

Latitude of highest peak 601 139 740 260 1,000

Longitude of highest peak 601 140 740 260 1,000

Descriptions of island groups

Number of islands in island group 1,000 0 1,000 0 1,000

Area of island group 1,000 0 1,000 0 1,000

Percentage of island group area represented 

by island area

1,000 0 1,000 0 1,000

Qualitative measures of topography and shape

Topographic type 660 0 660 340 1,000

Shape type 999 0 997 3 1,000

Dimensional measures

Length 734 0 734 266 1,000

Width 734 0 734 266 1,000

Effective radius 1,000 0 1,000 0 1,000

Radius of gyration 267 0 267 733 1,000

Perimeter 267 0 267 733 1,000

Fractal dimension of coastline 267 0 267 733 1,000

Compactness 1 734 0 734 266 1,000

Compactness 2 267 0 267 733 1,000

Compactness 3 267 0 267 733 1,000
Primary Island Set 41

Geologic Parameters

A first-order synthesis of the geology of the 

1,000 islands is provided in terms of 15 parameters. 

The parameters may be partitioned into the following 

groups that:

• Identify the islands in relation to specific features 

of the Earth’s surface;

• Summarily describe the geology of the islands and 

geologically characterize the island groups to 

which the islands belong;

• Account for the general chronology of island volcanism, and

• Provide a general geologic topology of the islands.

Relational Features of the Earth’s Surface

Of fundamental importance to geophysical studies is the partition of the Earth’s lithosphere into a number of “plates” and the movement of those plates 

relative to one another. Herein, the Earth’s surface is 

considered to be partitioned into 16 plates (table 12).

The plates that contain the 1,000 islands are 

identified in figure 16. In the case where an island lies 

near two plates, say P1 and P2, and it was difficult to 

discern, with the information at hand, on just which of 

the two plates the island is situated, the plate boundary 

was identified and noted as follows:

• P1– P2 if the boundary is a constructive margin; 

that is, a spreading margin, or 

• P1/P2 if the boundary is a convergent margin 

where plate P2 is being subducted under plate P1.

The global distribution of the islands over the 

lithospheric plates is shown in figure 16.

Islands are distributed along specific tracts over 

the ocean floor in the form of clusters or alignments, 

which are referred to as “chains,” or in isolated states. 

An island tract is characterized as being of a common 

or closely similar geologic origin; this is a more or less 

distinct geologic process that has led to the occurrence 

of the islands along a given tract. However, despite the 

common basic geology that underlies a given tract, 

variations are found in the geologic characterization of 

the individual islands that are on the tract. Each tract 

conveys categorical information that is referred to as 

“quipu,” which is the name of bundles of knotted ropes 

used by the Incas to transmit information. Six quipu 

categories are listed in table 13.

Each of the 1,000 islands is coded according to 

its quipu category. The quipu categories associated 

with the islands are shown in figure 17.

Table 12. Lithospheric plates

Count Name Code

1 Adriatic AD

2 Aegean AG

3 African AF

4 Antarctic AN

5 Arabian AR

6 Caribbean CB

7 Cocos CO

8 Eurasian EA

9 Indian – Australian IA

10 North American NA

11 Nazca NZ

12 Pacific PA

13 Philippine Sea PH

14 Scotian SC

15 South American SA

16 Turkish TU

Table 13. Quipu categories

Count Category Code

1 Islands on a continental margin

2 Islands on a spreading center or an oceanic ridge 

of other origin

3 Islands within an island arc

4 Islands on sea mounts

5 Islands on carbonate oceanic banks

6 Islands on continental blocks

α

β

γ

δ

ε

ζ
42 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets E u r a s i a n P l a t e Arabian Plate African Plate Philippine Sea Plate I n d i a n - A u s t r a l i a n P l a t e

A n t a r c t i c P l a t e

Cocos

Plate

P a c i f i c P l a t e

P a c i f i c P l a t e

A n t a r c t i c P l a t e

N a z c a

P l a t e

Caribbean

Plate

N o r t h A m e r i c a n P l a t e

N o r t h A m e r i c a n P l a t e

Scotia Plate

S o u t h

A m e r i c a n

P l a t e

A f r i c a n

P l a t e

E u r a s i a n

P l a t e

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

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20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Lithospheric plate boundaryIsland arc islandContinental islandOceanic island

Figure 16. Global distribution of islands per lithospheric plates.
Primary Island Set 43 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Quipu category

Continental marginOceanic ridgeIsland arc

Sea mountCarbonate bankContinental block

Figure 17. Global distribution of islands per Quipu category.
44 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Geologic Classification

The geologic type of each of the 1,000 islands is 

identified by an alphanumeric code; the alpha part 

identifies the geologic “class” of an island, and the 

numeric part, the geologic “species” of an island. The 

geologic class is noted by one of three letters, A, C or 

O, to indicate the general geologic aspects shared by 

the island of a particular class. 

Along convergent plate margins, ridges form 

island arc systems. The ridges tend to have an arcuate 

pattern, the inner sides being concave to the adjacent 

continents and the outer sides being fronted by deep 

trenches where ocean depths are in excess of the adjacent ocean floor. Where transcurrent fault zones are 

large, the arcuate pattern of the ridges is distorted, the 

resultant pattern being referred to as a “fractured island 

arc.” In general, the arcuate ridges are paired; the outer 

ridge comprises sedimentary rocks, and the inner ridge, 

mainly volcanic material. The arc-trench systems, 

which may be several thousand kilometers in length 

with widths of only a few hundred kilometers, are parts 

of two major active orogenic belts that girdle the Earth, 

the Eurasian–Melanesian and the East Asian–Cordilleran, or the circum-Pacific (Wilson, 1954). The emerged 

portions of the ridges make up the class A islands.

The class C islands, (that is, the continental 

islands), are those islands that rise above the Continental Shelf, or slope, and islands that are associated with 

isolated continental fragments. Among the isolated 

continental islands are the Seychelles, which were connected to Madagascar in the Mesozoic or early Tertiary 

but now, as a consequence of plate tectonics, remotely 

located in the northwestern sector of the Indian Ocean. 

Islands included in class C vary from very large blocks 

to small rocky islands and reefs. Included are islands 

along the continental margins that are remnants of 

Pleistocene moraines, stabilized deposits of terrigenous and bioclastic sands, and aerial exposures of carbonate formation.

The remaining islands are grouped as class O 

islands. Most of these are directly or indirectly the 

product of volcanism associated with spreading centers, abyssal flood basalts, or ocean basin volcanoes. 

Those indirectly attributed to volcanism are the islets of 

atolls, which are coraline formations supported on the 

flanks of submerged ocean basin volcanoes. Included 

in class O are islands associated with carbonate banks 

that rise above the deep ocean floor.

The class C, A and O islands are partitioned into 

11, 5 and 8 subclasses, respectively, referred to as “species.” To fully account for the Earth’s dry-land surface, 

the continents, which in a geographic sense are islands, 

also, are assigned to class C. The continents are 

assumed not be geologically differentiated among 

themselves, whereby the species of each continent, as 

such, is indicated by the number zero (0; table 14).

Table 14. Continent and island geologic types

Count Category Subcategory Code

Continents

1 Continental Continent C-0

Islands

1 Continental Tectonic block C–1

2 Structural block C–2

3 Margin – Composite C–3

4 Margin –Igneous/metamorphic C–4

5 Margin – Volcanic C–5

6 Margin – Sedimentary C–6

7 Margin – Carbonate C–7

8 Margin – Depositional C–8

9 Orogenic – Cordilleran Archipelago

C–9

10 Orogenic – Alpine Archipelago C–10

11 Shield/Platform Archipelago C–11

1 Arc Orogenic A–1

2 Outer Arc A–2

3 Carbonate/volcanic A–3

4 Carbonate A–4

5 Volcanic/mafic A–5

1 Oceanic Carbonate Bank/ridge O–1

2 Nonvolcanic in an atoll O–2

3 Makatea/no volcanic exposed O–3

4 Carbonate/volcanic O–4

5 Volcanic/mafic O–5

6 Volcanic in an atoll O–6

7 Makatea/volcanic exposed O–7

8 Plateau volcanic O–8
Primary Island Set 45

Each of the 1,000 islands is classified as to its 

geologic type.

The global distributions of the islands per their 

geologic classes is shown in figure 18, and per their 

geologic species conditioned on the geologic classes A, 

C and O, respectively are shown in figures 18 though 

20. Figure 22 shows the global distribution of the 

islands that comprise carbonate rocks, (that is, the A–4, 

C–7 and O–1 islands); volcanic rocks, (that is, the A–5, 

C–5 O–5, O–6 and O–7 islands); and carbonate and 

volcanic rocks, (that is, the A–3, O–4 and O–7 islands).

A metric was devised for quantitatively measuring the extent of difference between two islands as 

reflected by their geologic types, the difference being 

termed the “geologic distance.” The geologic distance 

assumes 1 of 18 discrete values in the range (0, 200):

If two islands are of the same geologic type, then 

the geologic distance between them is zero (0), no matter how far apart the two islands are situated on the surface of the Earth. Geologic distance equal to 0 indicates 

that the two islands evolved by means of the same kind 

of geologic process in a common geologic province 

marked by the first-level geologic classifications of the 

islands. At most, the geologic distance between two 

islands is 200, which indicates that the islands have 

evolved by means of distinctly different geologic processes in different geologic provinces. The geologic 

distance between one island and the next along the tract 

of the Alisida is specified (table 15).

The islands belong to 1 of 299 island groups. The 

geologic class of an island group is defined in reference 

to the geologic classes of the islands that belong to the 

island group. If the islands of an island group are all of 

the same geologic class A, C or O, then the island group 

is of the same geologic class, which is indicated by the 

appropriate geologic class code. For example, all the 

islands that belong to the Fiji island group are class A 

islands, and, therefore, the Fiji island group is a geologic class A island group. If, however, the islands in an 

island group are of different geologic classes, then the 

geologic class of the island group is defined to be 

jointly of those classes, which is indicated by the 

appropriate geologic class codes arranged in alphabetic 

order. For example, the Greater Sunda island group has 

geologic class A and C islands, and, therefore, the 

island group is designated as being of geologic class 

AC. For each island, the geologic class of its associated 

island group is given. 

Volcanism

The 1,000 islands are partitioned into two sets — 

one set including those islands on which there are no 

volcanoes, and the other set, those islands on which 

there are volcanoes. Among the islands in the first set 

are the islets of atolls that are supported on submerged 

volcanic sea mounts. For islands in the first set, there 

obviously has been no volcanic activity, and, therefore, 

the islands are accordingly marked by the code letter N, 

which indicates that any attribute of volcanism is nonapplicable. An island in the second set is coded to indicate the most recent time when volcanism was active 

on the island — HI (historical), HO (Holocene), P

(prior to Holocene), † (not applicable), and ‡ (not 

determined). 

The global distribution of the islands per the 

most recent period of volcanic eruption is shown in 

figure 23.

Geologic Topology

The geologic topology of the islands is described 

in reference to an island’s geologic “neighbors.” Each 

island has three geologic neighbors — the nearest 

island of the same geologic class and the two nearest 

islands of the other two geologic classes. The positional distances between geologic neighbors are great 

circle distances measured in kilometers . See 

Appendix A. 

For each island, its geologic neighbor is identified by name, ID number and geologic class, and the 

positional distance between the islands is given.

Summary

The island coverages by the 15 geologic parameters are summarized in table 16.

0 5 10 15 20 25

30 35 40 50 55 60

100 120 140 160 180 200
46 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Geologic class

Island arcContinentalOceanic

Figure 18. Global distribution of islands per geologic class.
Primary Island Set 47 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

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20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Geologic species within class A (island arc)

1—Orogenic2—Outer arc3—Carbonate/volcanic

4—Carbonate5—VolcanicClass C or O

Figure 19. Global distribution of islands per geologic species conditioned on geologic class A.
48 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Geologic species within class C (continental)

1—Tectonic block2—Structural block3—Composite4—Igneous/volcanic5—Volcanic6—Sedimentary

7—Carbonate8—Depositional9—Orogenic-cordilleran10—Orogenic-alpine11—Shield/platformClass A or O

Figure 20. Global distribution of islands per geologic species conditioned on geologic class C.
Primary Island Set 49 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Geologic species within class O (oceanic)

1—Carbonate bank/ridge2—Non-volcanic in an atoll3—Makatea/non-volcanic4—Carbonate/volcanic5—Volcanic/mafic

6—Volcanic in an atoll7—Makatea/volcanic8—Plateau volcanicClass A or C

Figure 21. Global distribution of islands per geologic species conditioned on geologic class O.
50 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Carbonate rockVolcanic rockCarbonate and volcanic rockOther

Figure 22. Global distribution of islands composed of carbonate or volcanic rocks.
Primary Island Set 51

Table 15. Geologic distance between two islands of specific geologic types

C-0 C-1 C-2 C-3 C-4 C-5 C-6 C-7 C-8 C-9 C-10 C-11 A-1 A-2 A-3 A-4 A-5 O-1 O-2 O-3 O-4 O-5 O-6 O-7 O-8

C-0 0 30 50 50 50 50 50 50 50 50 50 40 200 240 240 240 240 180 240 240 240 240 240 240 180

C-1 30 0 20 40 40 40 40 40 40 40 40 40 160 200 200 200 200 180 200 200 200 200 200 200 180C-2 50 20 0 30 30 30 30 30 30 25 25 30 160 200 200 200 200 180 200 200 200 200 200 200 180C-3 50 40 30 0 20 20 20 20 20 30 30 30 200 160 200 200 200 180 200 200 200 200 200 200 160C-4 50 40 30 20 0 20 20 20 20 30 30 30 200 200 200 200 200 200 200 200 200 200 200 200 180C-5 50 40 30 20 20 0 20 20 20 30 30 30 200 200 180 200 120 200 180 200 160 120 180 180 180C-6 50 40 30 20 20 20 0 10 10 30 30 30 180 160 200 160 200 160 200 160 200 200 200 200 200C-7 50 40 30 20 20 20 10 0 10 30 30 30 200 180 180 120 200 120 160 120 200 200 180 180 200C-8 50 40 30 20 20 20 10 10 0 30 30 30 200 180 200 180 200 180 200 180 200 200 200 200 200C-9 50 40 25 30 30 30 30 30 30 0 10 30 140 160 200 200 200 200 200 200 200 200 200 200 200

C-10 50 40 25 30 30 30 30 30 30 10 0 30 180 160 200 200 200 200 200 200 200 200 200 200 200C-11 40 40 30 30 30 30 30 30 30 30 30 0 200 160 160 160 160 200 200 200 200 200 200 200 200

A-1 200 160 160 200 200 200 180 200 200 140 180 200 0 20 50 50 50 200 200 200 200 200 200 200 200A-2 240 200 200 160 200 200 160 180 180 160 160 160 20 0 50 50 50 180 180 180 200 200 200 200 200A-3 240 200 200 200 200 180 200 180 200 200 200 160 50 50 0 30 10 180 180 180 160 180 160 180 200A-4 240 200 200 200 200 200 160 120 180 200 200 160 50 50 30 0 30 160 160 180 180 200 160 180 200A-5 240 200 200 200 200 120 200 200 200 200 200 160 50 50 10 30 0 200 180 200 160 100 180 180 180

O-1 180 180 180 180 200 200 160 120 180 200 200 200 200 180 180 160 200 0 10 5 35 40 25 30 60O-2 240 200 200 200 200 180 200 160 200 200 200 200 200 180 180 160 180 10 0 5 25 30 15 20 50O-3 240 200 200 200 200 200 160 120 180 200 200 200 200 180 180 180 200 5 5 0 30 35 20 25 55O-4 240 200 200 200 200 160 200 200 200 200 200 200 200 200 160 180 160 35 25 30 0 5 10 5 25O-5 240 200 200 200 200 120 200 200 200 200 200 200 200 200 180 200 100 40 30 35 5 0 15 10 20O-6 240 200 200 200 200 180 200 180 200 200 200 200 200 200 160 160 180 25 15 20 10 15 0 5 35O-7 240 200 200 200 200 180 200 180 200 200 200 200 200 200 180 180 180 30 20 25 5 10 5 0 30O-8 180 180 180 160 180 180 200 200 200 200 200 200 200 200 200 200 180 60 50 55 25 20 35 30 0
52 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

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80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Most recent period of volcanic eruption

HistoricHolocenePreholoceneUnspecifiedNot applicable—Non-volcanic island

Figure 23. Global distribution of islands per most recent period of volcanic eruption.
Primary Island Set 53

Hydrologic Parameters

There are very few islands for which there are 

hydrologic observations. Of those islands, few have 

sufficiently long records on the spatial and temporal 

coverage of the hydrologic fluxes — runoff, precipitation, and evapotranspiration — from which reasonably 

accurate estimates of the water balances of the islands 

may be obtained. Moreover there is no analytical 

framework by which the water balance of a particular 

island may be estimated from the water balances of 

other islands. For these reasons, a description of the 

hydrology of an island is limited to a hydrologic sketch 

of the island’s surface-water landscape.

Hydrologic Sketch

The hydrologic sketch of an island is expressed 

in terms of the presence or absence of nine specific 

hydrologic features that relate to rivers, springs, 

wetlands, lakes, and reservoirs. With respect to the 

sketches:

• The presence or absence of a feature is noted by 

the numerical score 1 or 0, respectively; 

• No account was taken of the frequency with which 

a particular feature is present on a given island — 

a numerical score 1 implies the presence of at least 

one expression of that feature;

• Rivers and springs are perennial if their discharges 

are sustained throughout the year and they are seasonal if they flow only during the “rainy season”;

• Wetlands refer to swamps, bogs, or marshes that 

are significant hydrologic aspects of an island;

• Lakes refer to natural water bodies and are 

accounted for independently of lakes that have 

been transformed into reservoirs;

Table 16. Island coverage, by geologic parameter

Parameter

Islands

Specified

A

Inapplicable 

B

Covered

A+B

Unspecified

C

Total

A+B+C

Lithospheric plate 1,000 0 1,000 0 1,000

Quipu 1,000 0 1,000 0 1,000

Island geologic type 1,000 0 1,000 0 1,000

Island group geologic class 1,000 0 1,000 0 1,000

Volcanism 1,000 0 1,000 0 1,000

Interisland geologic distance 1,000 0 1,000 0 1,000

Name of nearest type C island 1,000 0 1,000 0 1,000

ID (identification) number of nearest type C island 1,000 0 1,000 0 1,000

Positional distance to nearest type C island 1,000 0 1,000 0 1,000

Name of nearest type A island 1,000 0 1,000 0 1,000

ID (identification) number of nearest type A island 1,000 0 1,000 0 1,000

Positional distance to nearest type A island 1,000 0 1,000 0 1,000

Name of nearest type O island 1,000 0 1,000 0 1,000

ID (identification) number of nearest type O island 1,000 0 1,000 0 1,000

Positional distance to nearest type O island 1,000 0 1,000 0 1,000
54 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

• No account was taken of the quality of lake waters 

other than a general distinction between fresh and 

brackish where fresh implies potable in terms of 

salinity; 

• Rooftop catchments were not considered in 

accounting for the presence or absence of surface 

reservoirs;

• The presence of a perennial river or spring indicates the likelihood, though not the certainty, of 

the presence of a ground-water aquifer, but

• The absence of each of the hydrologic features 

does not necessarily imply the absence of aquifers.

Of the 1,000 islands:

• 643 are coded as CS, which indicates that for each 

of these island, its hydrologic sketch is complete; 

that is, all hydrologic features are scored;

• 211 are coded as PS, which indicates that for each 

of these islands, its hydrologic sketch is partially 

complete; that is, some of, but not all, the features 

are scored, and

• 146 (= 1,000 – 643 – 211) are coded as ‡, which 

indicates that for each of these islands, its hydrologic sketch is totally incomplete; that is, none of 

the features are scored owing to lack of success in 

obtaining pertinent information.

Many of the islands with incomplete sketches are 

located at high latitudes. Above 60° and below -60° latitude, many islands are extensively and permanently 

covered by ice and snow, and other islands have liquidphase hydrologies only during short summer seasons. 

For these islands, in terms of the hydrologic features 

considered herein, hydrologic sketches are not very 

meaningful, at least not in the form of complete 

sketches. Of the 643 islands with complete sketches, 

597 islands are located at low or mid-latitude where the 

sketches are more meaningful.

For the subset of islands with complete information relative to perennial and seasonal rivers jointly, to 

perennial and seasonal springs jointly, and to freshwater and brackish water lakes jointly, the global distributions of these paired hydrologic features are shown in 

figures 24, through 26, respectively. The global distributions of the islands with wetlands and the islands 

with surface reservoirs are shown in figures 27 and 28, 

respectively.

For the islands with complete information 

regarding the presence or absence of each individual 

hydrologic feature covered by figures 24, through 26, 

their global distributions are given in Appendix G.

Summary 

From the hydrologic literature, sketches could be 

constructed for few islands. Personal communications 

with hydrologists who have first-hand knowledge of 

the islands enabled a substantial island coverage by the 

nine hydrologic parameters to be obtained, as listed in 

table 17.

Table 17. Island coverage, by hydrologic parameter

Parameter

Islands

Specified

A

Inapplicable

B

Covered

A+B

Undetermined

C

Total

A+B+C

Hydrologic sketch code 1,000 0 1,000 0 1,000

Perennial river 794 0 794 206 1,000

Seasonal river 784 0 784 216 1,000

Perennial spring 776 0 776 224 1,000

Seasonal spring 727 0 727 273 1,000

Wetlands 715 0 715 285 1,000

Freshwater lake 815 0 815 185 1,000

Brackish water lake 690 0 690 310 1,000

Surface reservoir 812 0 812 188 1,000
Primary Island Set 55 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Types of rivers present

PerennialSeasonalPerennial and seasonalUnspecifiedNone present

Figure 24. Global distribution of island hydrologic features — Perennial or seasonal rivers.
56 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Types of springs present

PerennialSeasonalPerennial and seasonalUnspecifiedNone present

Figure 25. Global distribution of island hydrologic features — Perennial or seasonal springs.
Primary Island Set 57 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Types of lakes present

Fresh-water lakesBrackish-water lakesFresh- and brackish-water lakesUnspecifiedNone present

Figure 26. Global distribution of island hydrologic features — Fresh- or brackish-water lakes.
58 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Wetlands

PresentAbsentUnspecified

Figure 27. Global distribution of island hydrologic feature — Wetlands.
Primary Island Set 59 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Reservoirs

PresentAbsentUnspecified

Figure 28. Global distribution of island hydrologic feature — Surface reservoirs.
60 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Economic Parameters

The economies of the islands in terms of such 

factors as the number, type, and size of the various economic sectors, gross national product, and so forth, are 

not dealt with herein. On an island-by-island basis, 

such an economic account would be difficult to obtain. 

An overview of the general base for economic activities on the islands was limited to 30 parameters that 

may be partitioned into the following groups:

• Sovereignty of the islands;

• Population of the islands and of their

principal centers;

• Principal ports and airports on the islands, and

• Local time on the islands.

Sovereignty of Islands

Among the 1,000 islands, claims of sovereignty 

for 21 are presently (1995) unsettled, 19 of which are 

located below –60° (south) latitude where claims of 

sovereignty are not recognized by the signatories of the 

Antarctic Treaty. For each of these 21 islands, their 

sovereignty is noted as not applicable (†). Sovereignty 

of the other 979 islands is distributed among 90 countries. The names of the particular countries that have 

sovereignty over these islands are given with respect to 

each of the islands, where the names are the conventional, the short form if applicable, names reported by 

the U.S. Board on Geographic Names.

The following islands are politically partitioned 

into separate sectors that are sovereign parts of different countries:

1. Borneo (ID–495) — The northwestern sector (20 

percent of the island) forms the Malaysian States 

of Sabah and Sarawak, except for a small enclave 

(10 percent of the island) that forms the independent State of Brunei. The rest (70 percent of the 

island) is partitioned into the Indonesian Provinces of East, West, Central, and South Kalimantan;

2. Cyprus (ID–342) — The southern (Greek) part 

(60 percent of the island) is controlled by the 

internationally recognized Cypriot Government, 

the northern (Turkish) part (35 percent of the 

island) is recognized only by Turkey as the Turkish Republic of Northern Cyprus, and two 

enclaves (5 percent of the island) are sovereign 

bases of the United Kingdom;

3. Hispaniola (ID–165) — The western sector (40 

percent of the island) forms the Republic of Haiti, 

and the larger, eastern sector (60 percent of the 

island), the Dominican Republic;

4. Ireland (ID–31) — The northern sector (20 percent of the island) forms the United Kingdom’s 

administrative division of Northern Ireland, and 

the rest (80 percent of the island) forms the 

Republic of Ireland;

5. New Guinea (ID–820) — The western sector (50 

percent of the island) forms the Indonesian Province of Irian Jaya, and the eastern sector (50 percent of the island) forms the Papua New Guinean 

Province of Papua;

6. Saint Martin (ID–178) — The northern sector (50 

percent of the island) is part of the French overseas Department of Guadeloupe, and the southern 

sector (50 percent of the island) is part of the 

Netherlands Antilles;

7. Tierra del Fuego (ID–662) — The western sector 

(50 percent of the island) is part of Chile, and the 

eastern sector (50 percent of the island) is part of 

Argentina; 

8. Usedom (ID–7) — The western sector (90 percent 

of the island) is part of Germany, and the rest (10 

percent of the island) is part of Poland.

In the case where an island is partitioned into two 

or three sovereign parts, the names of the particular 

countries are given in alphabetic order; for example, 

the three distinct sovereign parts of Borneo (ID–495) 

are identified as Brunei; Indonesia; Malaysia.

The sovereignties of the 979 islands are distributed over 90 countries, and are each associated with a 

sovereignty identification number in reference to the 

rank order of the countries by the number of islands 

under their sovereignty. The countries, which are 

arranged in order from most to least number of islands, 

are assigned sovereignty ID numbers that correspond 

to their rank order numbers. For example, the United 

States has sovereignty over 96 islands, the most for any 

of the 90 countries, and accordingly the United States 

is assigned the sovereignty ID number of 1. In cases 

where the number of islands is the same for several 

countries, the countries being ordered alphabetically, 

each of the countries is assigned the sovereignty 
Primary Island Set 61

identification number equal to the average of the appropriate rank order numbers. For example, Mexico, 

Portugal, and Seychelles have ranks 25, 26 and 27, 

respectively, and each has sovereignty over 12 islands. 

The sovereignty ID number for each country is the 

average of the ranks of the countries, 26 = (25 + 26 + 

27)/3 (table 18).

Table 18. Distribution of islands by country

[f, frequency; cf, cumulative frequency; Sov. ID, sovereignty identification number]

Ordered by increasing number of islands Ordered alphabetically by country

Rank Country

Number of islands

Sov.

ID

Country

Number of islands

Sov.

f cf f cf ID

1 United States 96.0 96.0 1.0 Antigua and Barbuda 2.0 2.0 57.0

2 Indonesia 74.2 170.2 2.0 Argentina 1.5 3.5 68.0

3 France 68.5 238.7 3.0 Australia 22.0 25.5 14.0

4 United Kingdom 66.3 305.0 4.0 Bahamas 15.0 40.5 20.5

5 Japan 52.0 357.0 5.0 Bahrain 1.0 41.5 77.0

6 Greece 39.0 396.0 6.0 Barbados 1.0 42.5 77.0

7 Philippines 33.0 429.0 7.0 Belau 8.0 50.5 32.5

8 Canada 28.0 457.0 8.0 Brazil 5.0 55.5 39.0

9 Papua New Guinea 27.5 484.5 9.0 Brunei 0.1 55.6 89.5

10 Russia 26.0 510.5 10.0 Burma 2.0 57.6 57.0

11 Chile 23.5 534.0 11.0 Canada 28.0 85.6 8.0

12 Fiji 23.0 557.0 12.0 Cape Verde 10.0 95.6 29.5

13 Australia 22.0 579.0 14.0 Chile 23.5 119.1 11.0

14 Italy 22.0 601.0 14.0 China 6.0 125.1 37.0

15 Solomon Islands 22.0 623.0 14.0 Colombia 3.0 128.1 42.5

16 Federated States of 

Micronesia

18.0 641.0 17.5 Comoros 3.0 131.1 42.5

17 India 18.0 659.0 17.5 Cook Islands 7.0 138.1 35.0

18 Norway 18.0 677.0 17.5 Costa Rica 1.0 139.1 77.0

19 Vanuattu 18.0 695.0 17.5 Croatia 13.0 152.1 24.0

20 Bahamas 15.0 711.0 20.5 Cuba 2.0 154.1 57.0

21 Tonga 15.0 725.0 20.5 Cyprus 0.6 154.7 87.5

22 New Zealand 14.0 739.0 22.5 Denmark 10.0 164.7 29.5

23 Spain 14.0 753.0 22.5 Dominica 1.0 165.7 77.0

24 Croatia 13.0 766.0 24.0 Dominican Republic 0.6 166.3 87.5

25 Mexico 12.0 778.0 26.0 Ecuador 9.0 175.3 31.0
62 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

26 Portugal 12.0 790.0 26.0 Equatorial Guinea 2.0 177.3 57.0

27 Seychelles 12.0 802.0 26.0 Estonia 2.0 179.3 57.0

28 Netherlands 10.5 812.5 28.0 Federated States of

 Micronesia

18.0 197.3 17.5

29 Cape Verde 10.0 822.5 29.5 Fiji 23.0 220.3 12.0

30 Denmark 10.0 832.5 29.5 Finland 1.0 221.3 77.0

31 Ecuador 9.0 841.5 31.0 France 68.5 289.8 3.0

32 Belau 8.0 849.5 32.5 Germany 5.9 295.7 38.0

33 Kiribati 8.0 857.5 32.5 Greece 39.0 334.7 6.0

34 Cook Islands 7.0 864.5 35.0 Grenada 2.0 336.7 57.0

35 Marshall Islands 7.0 871.5 35.0 Guinea 1.0 337.7 77.0

36 Venezuela 7.0 878.5 35.0 Haiti 2.4 340.1 46.0

37 China 6.0 884.5 37.0 Honduras 3.0 343.1 42.5

38 Germany 5.9 890.4 38.0 Iceland 3.0 346.1 42.5

39 Brazil 5.0 895.4 39.0 India 18.0 364.1 17.5

40 Colombia 3.0 898.4 42.5 Indonesia 74.2 438.3 2.0

41 Comoros 3.0 901.4 42.5 Iran 1.0 439.3 77.0

42 Honduras 3.0 904.4 42.5 Ireland 0.8 440.1 86.0

43 Iceland 3.0 907.4 42.5 Italy 22.0 462.1 14.0

44 Tanzania 3.0 910.4 42.5 Jamaica 1.0 463.1 77.0

45 Vietnam 3.0 913.4 42.5 Japan 52.0 515.1 5.0

46 Haiti 2.4 915.8 46.0 Kiribati 8.0 523.1 32.5

47 Antigua and Barbuda 2.0 917.8 57.0 Madagascar 1.0 524.1 77.0

48 Burma 2.0 919.8 57.0 Malaysia 1.2 525.3 70.0

49 Cuba 2.0 921.8 57.0 Maldives 2.0 527.3 57.0

50 Equatorial Guinea 2.0 923.8 57.0 Malta 2.0 529.3 57.0

51 Estonia 2.0 925.8 57.0 Marshall Islands 7.0 536.3 35.0

52 Grenada 2.0 927.8 57.0 Mauritius 2.0 538.3 57.0

53 Maldives 2.0 929.8 57.0 Mexico 12.0 550.3 26.0

54 Malta 2.0 931.8 57.0 Nauru 1.0 551.3 77.0

55 Mauritius 2.0 933.8 57.0 Netherlands 10.5 561.8 28.0

Table 18. Distribution of islands by country

[f, frequency; cf, cumulative frequency; Sov. ID, sovereignty identification number]

Ordered by increasing number of islands Ordered alphabetically by country

Rank Country

Number of islands

Sov.

ID

Country

Number of islands

Sov.

f cf f cf ID

—Continued
Primary Island Set 63

56 Panama 2.0 935.8 57.0 New Zealand 14.0 575.8 22.5

57 Peru 2.0 937.8 57.0 Norway 18.0 593.8 17.5

58 Saint Kitts and Nevis 2.0 939.8 57.0 Oman 1.0 594.8 77.0

59 Sao Tome and Princip 2.0 941.8 57.0 Panama 2.0 596.8 57.0

60 South Africa 2.0 943.8 57.0 Papua New Guinea 27.5 624.3 9.0

61 South Korea 2.0 945.8 57.0 Peru 2.0 626.3 57.0

62 Sweden 2.0 947.8 57.0 Philippines 33.0 659.3 7.0

63 Thailand 2.0 949.8 57.0 Poland 0.1 659.4 89.5

64 Trinidad and Tobago 2.0 951.8 57.0 Portugal 12.0 671.4 26.0

65 Tuvalu 2.0 953.8 57.0 Russia 26.0 697.4 10.0

66 Western Samoa 2.0 955.8 57.0 Saint Kitts and Nevis 2.0 699.4 57.0

67 Yemen 2.0 957.8 57.0 Saint Lucia 1.0 700.4 77.0

68 Argentina 1.5 959.3 68.0 Saint Vincent and 

 Grenadines

1.0 701.4 77.0

69 Turkey 1.4 960.6 69.0 Sao Tome and Princip 2.0 703.4 57.0

70 Malaysia 1.2 961.8 70.0 Seychelles 12.0 715.4 26.0

71 Bahrain 1.0 962.8 77.0 Singapore 1.0 716.4 77.0

72 Barbados 1.0 963.8 77.0 Solomon Islands 22.0 738.4 14.0

73 Costa Rica 1.0 964.8 77.0 South Africa 2.0 740.4 57.0

74 Dominica 1.0 965.8 77.0 South Korea 2.0 742.4 57.0

75 Finland 1.0 966.8 77.0 Spain 14.0 756..4 22.5

76 Guinea 1.0 967.8 77.0 Sri Lanka 1.0 757.4 77.0

77 Iran 1.0 968.8 77.0 Sweden 2.0 759.4 57.0

78 Jamaica 1.0 969.8 77.0 Tanzania 3.0 762.4 42.5

79 Madagascar 1.0 970.8 77.0 Thailand 2.0 764.4 57.0

80 Nauru 1.0 971.8 77.0 Tonga 15.0 779.4 20.5

81 Oman 1.0 972.8 77.0 Trinidad and Tobago 2.0 781.4 57.0

82 Saint Lucia 1.0 973.8 77.0 Turkey 1.4 782.8 69.0

83 Saint Vincent and 

 Grenadines

1.0 974.8 77.0 Tuvalu 2.0 784.8 57.0

84 Singapore 1.0 975.8 77.0 United Kingdom 66.3 851.0 4.0

85 Sri Lanka 1.0 976.8 77.0 United States 96.0 947.0 1.0

Table 18. Distribution of islands by country

[f, frequency; cf, cumulative frequency; Sov. ID, sovereignty identification number]

Ordered by increasing number of islands Ordered alphabetically by country

Rank Country

Number of islands

Sov.

ID

Country

Number of islands

Sov.

f cf f cf ID

—Continued
64 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

For the remaining 21 (= 1,000 - 979) islands for 

which there are various unrecognized claims assignments of associated sovereignty identification numbers 

are not applicable (†).

The global distribution of the islands relating to 

the five highest frequencies of sovereignty are shown in 

figure 29. The global distributions of all the islands in 

reference to their sovereignties are depicted in figures 

57 through 74 in Appendix H.

Population of Islands and Principal Centers

The population of an island is a major determinant in the economic development of its resources. For 

example, the magnitude of the population and the economy that the population can support determines the 

demand (that is, willingness to pay) for the development of the island’s water resources. Although some 

islands are decreasing in population, others are increasing. For those whose population is growing, a contributing factor is a high birth rate relative to the death rate, 

[for example, the Seychelles (ID–355, ..., ID–366) in 

the Indian Ocean and the Marshall Islands (ID–885, ..., 

ID–889 and ID–892 and ID–893) in the Pacific Ocean] 

or a high immigration rate relative to the emigration 

rate [for example, the Hawaiian Islands (ID–969, ..., 

ID–978) in the Pacific Ocean]. Many archipelagos, particularly those that comprise “low islands” [for example, the Cook Islands (ID–910, ..., ID–916) in the 

Pacific Ocean] have small total land areas, and, therefore, the stress placed on their support systems by 

population growth gives meaning to sustainable development. A high rate of population growth coupled with 

a low rate of economic growth is characteristic of many 

of the world’s islands.

For those islands that are losing population [for 

example, the Azores (ID–250, ..., ID–258) in the Atlantic Ocean and the Hebrides (ID–33, ..., ID–48) off the 

west coast of Great Britain (ID–29)] the contributing 

factor is mainly a high rate of emigration relative to the 

rate of immigration. This is particularly the case among 

the younger and the more skilled individuals who leave 

in hope of securing a better future for themselves on the 

continental “mainlands.”

Of the 1,000 islands:

• 805 are coded as Y to indicate that the islands are 

permanently inhabited;

• 159 are coded as N to indicate that the islands are 

not permanently inhabited, and

• 36 are coded as ‡ to indicate that effort to determine whether or not the islands are permanently 

inhabited was not successful.

Counted among the permanently inhabited 

islands are those on which the only inhabitants are personnel of scientific stations (for example, stations for 

making meteorologic observations; conducting various 

types of research; and so forth) or of other government 

facilities (for example, prisons or military bases). 

Counted among the islands that are not permanently 

inhabited are those that are visited briefly during the 

year for one reason or another; for example, seeking 

temporary shelter during storms at sea or gathering of 

food.

Included among the 759 islands for which census values are given are:

• 600 of the 805 permanently inhabited islands, and 

the

86 Ireland 0.8 977.6 85.0 Vanuatu 18.0 965.0 17.5

87 Dominican Republic 0.6 978.2 86.5 Venezuela 7.0 972.0 35.0

88 Cyprus 0.6 978.8 86.5 Vietnam 3.0 975.0 42.5

89 Brunei 0.1 978.9 89.5 Western Samoa 2.0 977.0 57.0

90 Poland 0.1 979.0 89.5 Yemen 2.0 979.0 57.0

Table 18. Distribution of islands by country

[f, frequency; cf, cumulative frequency; Sov. ID, sovereignty identification number]

Ordered by increasing number of islands Ordered alphabetically by country

Rank Country

Number of islands

Sov.

ID

Country

Number of islands

Sov.

f cf f cf ID

—Continued
Primary Island Set 65 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Sovereign

United StatesIndonesiaFranceUnited Kingdom

JapanOtherUnspecified

Figure 29. Global distribution of islands relating to the five highest frequencies of sovereignty.
66 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

• 159 (= 759 – 600) islands that are not permanently 

inhabited and therefore have census values effectively equal to 0.

There remain 241 (= 1,000 – 759) islands for 

which census values are not given, of which:

• 36 are those for which permanent habitation could 

not be determined, and

• 205 (= 241 – 36) are those which are among the 

permanently inhabited islands.

With respect to the year of census:

• The census years are given for 570 of the 600 

islands whose census values are specified;

• Values are assumed to be inapplicable for the 159 

islands that are not permanently inhabited; 

whereby

• Values are effectively specified for 72 9(= 570 + 

159) islands; which leaves

• 271 (= 1,000 – 729) islands without specified values; of which

• 235 are permanently inhabited islands, and

• 36 (= 271 – 235) are islands for which habitation 

has not been determined.

The population densities, which are expressed to 

the nearest integer value of the number of individuals 

per unit area, are given for each of the 759 islands 

whose census values are specified.

A global perspective on the distribution of the 

island population densities is shown in figure 30.

For most permanently inhabited islands, their 

populations are concentrated at few centers. If an island 

is a sovereign part of a single nation, then one of the 

centers may be identified as the principal center, a principal center being defined as follows:

• If among the centers of population on a given 

island, one is the national capital (NC) of the 

island nation made up of that island and perhaps 

others, then that center is identified as the island’s 

principal center;

• If among the centers of population, none is a 

national capital, but one is the provincial or lower 

level administrative (AC) for the island as a whole, 

then that center is identified as the island’s principal center;

• If an island is partitioned into two or more provinces, then that center with the largest population 

is identified as the island’s principal center and is 

referred to as the “metro center” (MC); 

• If the only human habitat on an island is a meteorologic station (MS) or a research station (RS) or 

some other type of government facility (GF), then 

that station or facility is identified as the island’s 

principal center, and

• In the case of an island that is itself a single province or together with other islands forms a single 

province, if none of the island’s centers is a 

national capital or a provincial capital (PC) and if 

the size of the populations of the various centers 

are more or less the same, then the island is said 

not to have a principal center.

As defined, the principal center of an island is 

identified as being one of the six mutually exclusive 

types (table 19).

Herein an island was assumed to have but one 

principal center. Thus, in the case of an island partitioned into two or more different sovereign parts, the 

definition of a principal center was assumed to be not 

applicable (†). The definition of a principal center, 

however, can readily be extended to such islands by 

applying the definition to each part separately and then, 

by identifying the island’s set of principal centers.

Of the 1,000 islands:

• 585 are coded Y to indicate that the islands have 

principal centers;

• 159 are coded N to indicate otherwise, the islands 

being those that are not permanently inhabited;

• 8 are coded † to indicate that identification of a 

principal center is inapplicable, the islands being 

Table 19. Types of principal centers

Count Type Code

1 National capital NC

2 Other administratuve center AC

3 Metro center MC

4 Meteorologic station MS

5 Research station RS

6 Other government facility GF
Primary Island Set 67 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Population density—Persons per square kilometer

Not permanently inhabitedMore than 1 to 10More than 10 to 100More than 100 to 1,000

More than 1,000 to 10,000Greater than 10,000Unspecified

Figure 30. Global perspective on the distribution of island population density.
68 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Types of principal centers

Administrative center (other)Government facility (other)Metropolitan centerMeteorologic station

National capitalResearch stationUninhabited islandUnspecified

Figure 31. Global distribution of the types of island principal centers.
Primary Island Set 69

those that are partitioned into two or more sovereign parts, and

• 248 (= 1,000 – 585 – 159 – 8) are coded ‡ to indicate the matter of whether or not the islands have 

principal centers was not resolved.

The global distribution of types of principal population centers associated with the islands is shown in

figure 31.

Among the 585 islands identified as having principal centers and thereby coded Y:

• The names of the principal centers, which are official names reported by the U.S. Board on Geographic Names, are given for 581 of the islands;

• The censuses of the principal centers are given for 

173 of the islands;

• The years of census of the principal centers are 

given for 171 of the islands;

• The types of principal centers (see table 20) are 

given for each of the 582 islands;

• The geographic coordinates, latitude and longitude of the principal centers, which are expressed 

to the nearest hundredth degree, are given for 523 

of the islands, and

• The concentrations of the populations of the 

islands at the principal centers, which are the ratio 

of the principal center population to the island 

population, are given for 159 islands.

To each of these island counts the value 167 must 

be added to obtain the island coverages by the parameters noted in table 2; 167 is the sum of the 159 islands 

identified as not having principal centers (coded N) and 

the 8 islands partitioned into two or more sovereign 

parts (coded †).

Principal Seaports and Airports

Important to the economic well-being of an 

island is the availability of facilities for off-island 

transportation (commercial shipping and flight) of people and goods and that link the island to markets 

abroad. The islands where these means of transport 

exist were identified in reference to a listing of the 

world’s seaports by the U.S. Defense Mapping Agency 

(1988) and a listing of the world’s airports by the International Civil Aviation Organization (1992). If an 

island has but a single seaport or airport, then that seaport or airport is referred to as the island’s principal 

seaport or airport. In the case where an island has more 

than one seaport or airport, then the principal seaport or 

principal airport was considered to be one that serves 

the island’s principal center. No count was made of the 

numbers of seaports and airports for any of the islands. 

Information about the island seaports and airports were 

obtained from governmental and intergovernmental 

sources.

Of the 1,000 islands:

• 372 are coded as Y to indicate that these islands 

have principal seaports, and

• 628 (= 1,000 – 372) are coded as N to indicate 

otherwise.

For each of the 372 islands coded Y, the name of 

the principal seaport (official or if applicable, conventional name reported by the U.S. Board on Geographic 

Names) is given, and for 370 of the islands:

• The geographic coordinates, latitude and longitude (expressed to the nearest hundredth degree), 

of the seaports are given;

• The port types are indicated by the codes listed in 

table 20, and 

• The seaport sizes are indicated as being large (L), 

medium (M), small (S), or very small (V).

To each of these island counts, the value 628 

must be added to obtain the island coverages given in 

table 2 for these particular parameters; 628 is the number of islands without seaports and, therefore, the number of islands for which the parameter values are not 

applicable (†).

Of the 372 principal seaports:

• 165 are coded as Y to indicate that goods and individuals may clear customs at these seaports;

• 42 are coded as N to indicate otherwise, and

• 165 (= 372 – 165 – 42) are coded as ‡ to indicate 

that for these seaports it was not determined if 

goods and individuals may clear customs.
70 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Thus, there are 207 (= 165 + 42) islands with 

seaports for which the matter of whether or not goods 

and individuals may clear customs was not specified. 

To this island count, the value 628 must be added to 

obtain the island coverage given in table 2 that corresponds to the particular parameter. For further discussion regarding the size and type classifications of the 

seaports and clearance of customs at the seaports, see 

U.S. Defense Mapping Agency (1988).

Construction of facilities to provide or enhance 

interisland air transport impacts an island’s environment. The impact may be extensive on small islands 

whose terrains or coastlines are significantly altered. A 

case in point is Johnston Island (ID–961). Prior to 

1939, it had an area of 0.19 km2

. Between 1939 and 

1945, the island was leveled, and its area increased to 

0.85 km2

 to accommodate military operations during 

World War II. From 1963 to 1964, extension of the airport runway increased the island’s area to 2.3 km2

. For 

many small, low islands, paved runways serve as catchments of rainfall to augment the supply of freshwater 

supplied by the islands natural ground-water reservoir.

Of the 1,000 islands:

• 377 are coded Y to indicate that these islands have 

principal airports, and

• 623 (= 1,000 – 377) are coded N to indicate otherwise.

Of the 377 islands coded Y:

• The names of the principal airports, official or if 

applicable, conventional names reported by the 

U.S. Board on Geographic Names, are given for 

each of the 377 islands;

• The code letters that identify the airports are given 

for 357 islands;

• The geographic coordinates, latitude and longitude (expressed to the nearest hundredth degree), 

of the airports are given for 185 airports;

• The elevations of the airports, which are measured 

in meters, are given for 143 islands, and

• The lengths of the longest runways, which are 

measured in meters, are given for 170 airports.

To each of these island counts, the value 623 

must be added to obtain the island coverages of the 

parameters as noted in table 2; 623 is the number of 

islands without principal airports.

Of the 377 principal airports:

• 148 are coded as Y to indicate that goods and individuals may clear customs at the airports, and

• 229 are coded as N to indicate otherwise.

Thus, the matter of whether or not goods and 

individuals may clear customs is specified for each of 

the 377 (= 148 + 229) islands with airports. To this 

island count the value 623 must be added to obtain the 

island coverage noted in table 2.

The global distribution of islands with ports or 

airports is shown in figure 32.

Table 20. Classification of seaport types

Type Description Code

Coastal: Breakwater Coastal harbor behind a manmade breakwater constructed to provide shelterCB

Natural Coastal harbor sheltered by its location within a natural 

coastal indentation or in the protective lee of an island 

or other natural barrier 

CN

Open roadsteadPort that has no natural or artificial barrier for protection OR

River: Basin Harbor located in a river in which slips have been excavated in the riverbanksRB

 Natural Harbor located in a river, the waters of which are not 

retained by artificial means

RN

 
Primary Island Set 71 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Transport facilities

SeaportAirport

Seaport and airportNone

Figure 32. Global distribution of offshore transportation facilities.
72 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Local Time

Local time is defined in reference to the system 

of standard time zones adopted at the 1884 International Meridian Conference in Washington, D.C. 

(Brown, 1949). There are 24 time zones, each spanning 

15° of longitude. The zero-th time zone, which is centered on Greenwich meridian, extends from -7.5° longitude to 7.5° longitude. The time zone entered on 180° 

longitude is divided into two parts. The part that 

extends from -172.5° longitude to 180° longitude is 

designated as zone 12, and the part that extends from 

180° longitude to 172.5° longitude is designated as 

zone -12. With mean solar time at the Greenwich 

meridian, which is denoted as Universal Time (UT) or 

Greenwich Mean Time (GMT), set equal to zero, local 

time (that is, the time within another zone), differs from 

GMT by an integral number of hours, but the minutes 

and seconds are the same. Local time decreases 

(increases) by one hour in moving progressively from 

one zone to another eastward (westward) from Greenwich to zone -12 (12). A 13th time zone that has the 

same hour as zone 11 has been introduced to allow 

some countries and island groups to retain the same 

calendar day. Below -60° latitude, local time does not 

accord with the time zones. Scientific parties in that 

region take as their local times those of their sponsoring countries.

Many countries prefer to conduct their affairs 

without strict adherence to the universal system of 

fixed time zones, and, therefore, by law have changed 

their local times to “legal” or “standard” times. Also 

many countries modify their standard times during part 

of the year, particularly during the summer to increase 

the number of daylight hours. The modification, which 

is achieved by adopting the standard time of the zone 

immediate to the east, advances the local time by 1 

hour. Some countries maintain the modified local time 

throughout the year. 

The International Date Line is a specifically set 

line that approximates the 180° longitude. By international agreement, a traveler upon crossing the line must 

change the date by 1 calendar day. The date is increased 

(decreased) by 1 calendar day when traveling eastward 

(westward) across the line.

For each of the 981 islands above -60° latitude, 

their “standard” times are given. For the other 19 (= 

1,000 - 981) islands below -60°, where local time is not 

defined by time zone, the “standard” times are noted as 

being not applicable (†).

Summary

A condensed version of the 30 Economic Parameters are listed in table 21. 

Table 21. Island coverage, by economic parameter

Parameter

Islands

Specified

A

Inapplicable

B

Covered

A+B

Unspecified

C

Total

A+B+C

Sovereignty

Name of nation 979 21 1,000 0 1,000

Sovereignty ID (identification) number 979 21 1,000 0 1,000

Island habitation

Code that indicates if an island is 

permanently inhabited

964 0 964 36 1,000

Census 759 0 759 241 1,000

Year of census 570 159 729 271 1,000

Density 759 0 759 241 1,000

Principal center habitation

Code that indicates if an island has a 

principal center

744 8 752 248 1,000

Name 581 167 748 252 1,000

Census 173 167 340 660 1,000
Primary Island Set 73

Environmental Parameters

Islands constitute unique platforms for making 

meteorologic observations because of their remoteness 

from large centers of human activity concentrated on 

the continents.

If predictions of global warming by means of 

increasing levels of “greenhouse” gases in the atmosphere are realized, then many of the world’s islands 

will be impacted one way or another. For some islands, 

the impacts may be adversely severe. Among the “low” 

islands, some may become submerged if global warming occasions sea level to rise appreciably, say by several centimeters. Other islands, “low” or “high,” could 

be effected in terms of increased coastal erosion, accelerated rates and increased volumes of sediment discharge, or diminution of fresh ground-water supplies 

along coastal reaches by means of saltwater intrusion 

Year of census 171 167 338 662 1,000

Type 582 167 749 251 1,000

Latitude 523 167 690 310 1,000

Longitude 523 167 690 310 1,000

Concentration 159 167 326 673 1,000

Port

Code that indicates if an island has a 

principal port

1,000 0 1,000 0 1,000

Name 372 628 1,000 0 1,000

Latitude 370 628 998 2 1,000

Longitude 370 628 998 2 1,000

Code that indicates if customs may be 

cleared

207 628 835 165 1,000

Size 370 628 998 2 1,000

Type 370 628 998 2 1,000

Airport

Code that indicates if an island has a 

principal airport

1,000 0 1,000 0 1,000

Name 377 623 1,000 0 1,000

Code letters 357 623 980 20 1,000

Latitude 185 623 808 192 1,000

Longitude 185 623 808 192 1,000

Code that indicates if customs may be 

cleared

377 623 1,000 0 1,000

Elevation 143 623 766 234 1,000

Length of longest runway 170 623 793 207 1,000

Local time

International time zone 1,000 0 1,000 0 1,000

Table 21. Island coverage, by economic parameter

Parameter

Islands

Specified

A

Inapplicable

B

Covered

A+B

Unspecified

C

Total

A+B+C

—Continued
74 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

of aquifers. The environment of islands could be further effected by global warming in terms of changes in 

the mix of types and coverages of vegetation and by 

changes in bacterial populations that could adversely 

affect the health of the island inhabitants. Some 

impacts could lead to decreases in economic productivity. It may well be that some islands, perhaps those in 

polar climes, would benefit from a warmer climate. 

To assess the impact of global warming on island 

environments, more complete biologic descriptions of 

the islands are needed. To assess the extent to which the 

Earth’s climate is changing and if anthropomorphically 

induced changes are, at least in the short-run, overriding or augmenting natural changes, more extensive 

spatial and temporal meteorologic coverage of the 

world’s islands are needed.

A limited description of the environment of the 

islands is provided in terms of the general climatic 

states of the islands. The climatic states are of local 

importance in so far as they define the habitability of 

the islands and the viability of their economic growth. 

The climatic states also are of global importance in that 

the islands provide a valuable platform on the Earth’s 

climate over the oceanic expanse. 

The descriptions of the island environments are 

given by 17 parameters that may be partitioned into the 

following groups that provide:

• Quantitative measures of the local meteorology of 

islands;

• Markers of long-term island climates, and

• Measure of current relative states of wetness/dryness of islands.

Local Meteorology of Islands

In this study, the information about the local 

meteorology of an island is limited to the following: 

• Mean annual precipitation, which is measured in 

millimeters, and 

• Mean annual temperature, which is measured in 

degrees Celsius,

determined at specific locations on the island, where 

the descriptors are qualified by the

• Elevation, which is measured in meters, of the station where precipitation or temperature observations are recorded, and 

• Length of precipitation or temperature record, 

which is measured in the number of years of 

observation.

Except for a small, low island, the local meteorology does not reflect the general or average meteorology of the island as a whole. For many of the small 

islands, there is, at most a single meteorologic station. 

If an island, small or large, has two or more meteorologic stations, then only one of the stations is taken into 

account, namely the station with the longest record. In 

most cases, the station selected is located at or near the 

island’s principal center. Most of the principal centers 

are located on the coast, and therefore, an island’s local 

meteorology is, in most cases, defined at that location. 

However, because an island’s local meteorology is 

effected orographically by its topography, its local 

meteorology does not necessarily reflect that at the 

surface of the nearby sea. 

Of the 1,000 islands:

• 320 are coded as PT to indicate that the local 

meteorologies for those islands are specified by 

values of mean annual precipitation and mean 

annual temperature;

• 98 are coded as P to indicate that the local meteorologies for those islands are specified only by 

values of mean annual precipitation;

• 11 are coded as T to indicate that the local meteorologies for those islands are specified only by 

values of mean annual temperature; whereby there 

are

• 418 (= 320 + 98) islands for which values of mean 

annual precipitation are specified; and

• 331 (= 320 + 11) islands for which values of mean 

annual temperature are specified; which leaves

• 571 (= 1,000 – 320 – 98 – 11) islands that are 

coded as ‡ to indicate that for those islands, it 

could not be determined if observations of precipitation and temperature on the islands are available. 

Among the 418 islands coded PT or P relative to 

observations of precipitation, there are:

• 184 islands for which the station elevations are 

given;

• 224 islands for which the lengths of records are 

given, and
Primary Island Set 75 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Station type

PrecipitationTemperature

Precipitation and temperatureNone

Figure 33. Global distribution of island meteorological stations.
76 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

• 181 islands for which the station elevations and 

the lengths of records are given.

Among the 331 islands coded PT or T relative to 

observations of temperature, there are:

• 237 islands for which the station elevations are 

given;

• 243 islands for which the lengths of records are 

given, and

• 211 islands for which the station elevations and 

the lengths of records are given.

The global distribution of islands with recordings of precipitation or temperature is shown in figure 

33.

Climatic Markers

The general climates of the islands are reflected 

in the various biological and physical parameters of the 

islands. In particular, nine parameters serve as markers 

that delineate three climatic states (table 22).

The parameters, however, do not provide precise 

markings of climatic states, for example:

• Palms are not restricted to a particular species — 

coconut palms (Cocos nucifera) are limited to 

tropical and subtropical climates, whereas date 

palms (Phoenix dactylifera) are found in relatively 

dry warm climates;

• Apart from Glaciation, the parameters are scored 

as 1 or as 0, respectively, whether they are or are 

not manifest on a particular island (Glaciation is 

described by a more detailed scoring scheme);

• Apart from Glaciation, a parameter reflects the 

more recent climatic environment of an island, for 

example, no account is taken whether or not peat 

is still forming on a particular island; 

• Glaciation reflects the current polar state of an 

island relative to the island’s polar state during the 

Pleistocene; a more remote polar state cannot be 

reflected since many of today’s islands did not 

exist prior to the Pleistocene, particularly the oceanic islands (geologic type O islands) and the 

islands in island arcs (geologic type A islands).

The global distributions of the islands in the 

tropical/subtropical, temperate, and subpolar/polar climatic states are shown in figures 34 through 36, respectively.

The scheme for scoring Glaciation is given in 

table 23.

The global distribution of islands per their scale 

of glaciation is shown in figure 37.

.

Table 22. Island climates

Count Climatic state Parameter (marker)

1 Tropical / subtropical Mangroves

Coral reefs

Tropical peat

Palms

2 Temperate Seasonal snow / ice

Sphagnum peat

3 Subpolar / polar Permafrost

Permanent snow / ice

Glaciation

Table 23. Scale of island glaciation

Present Pleistocene Score

Glaciated combination observed on Earth

None None 0

High mountain 1

Mountain 2

Entirely glaciated 3

Only high mountain Entirely glaciated or just 

reached by ice sheets

4

Overrun by ice sheets 5

Glaciated Glaciated 6

Glaciated combination not observed on Earth

Glaciated None †
Primary Island Set 77 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Polar climatic-state characteristics

PermafrostPermafrost and glaciersPermafrost, glaciers, and iceGlaciers and ice

GlaciersOther climatic stateUnspecified

Figure 34. Global distribution of islands per polar climatic state.
78 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Temperate climatic-state characteristics

Seasonal icePeatSeasonal ice and peat

Other climatic stateUnspecified

Figure 35. Global distribution of islands per temperate climatic state.
Primary Island Set 79 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Tropical climatic-state characteristics

Tropical peatPalmMangrovePalm and coralPalm and mangrove

Palm, coral, and mangrovePeat, palm, and coralPeat, palm, coral, and mangroveOther climatic stateUnspecified

Figure 36. Global distribution of islands per tropical climatic state.
80 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Scale of glaciation

Score 0 1 2 3 4 5Unspecified

Present None None None None High-mountain High-mountain

Pleistocene None High-mountain Mountain Entirely glaciated Entirely glaciated or just reached by ice sheets Overrun by ice sheets

Figure 37. Global distribution of islands per scale of glaciation.
Primary Island Set 81

Table 24. Distribution of islands, by hydrologic feature and class 

[pR- perennial river; pS- perennial spring; wL- wetlands; fL- freshwater lake; CS- complete sketch; PS- partial sketch; 

f- frequency = total number of islands sketched per hydrologic class; cf- cumulative frequency; (.), total number of islands]

Hydrologic features Islands sketched Islands classified

pR pS wL fL CS PS f cf

Hydrologic class 1 (dry)

0 000 175 6 181 181

Hydrologic class 2

0 010 24 3

0 001 7 2

0 011 8 5

(39) (10) 49 230

Hydrologic class 3

0 100 62 4 66 296

Hydrologic class 4

0 110 22 1

0 101 6 0

(28) (1) 29 325

Hydrologic class 5

0 111 13 1 14 339

Hydrologic class 6

1 000 3 0

1 010 3

1 001 2 2

1 011 15 0

(23) (2) 25 364

Hydrologic class 7

1 100 77 0 77 441

Hydrologic class 8

1 110 66 4 70 511

Hydrologic class 9

1 101 40 3 43 554

Hydrologic class 10 (wet)

1 111 120 4 124 678
82 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Hydrologic Classes

On the basis on the hydrologic sketches discussed above, the islands are classified on a general 

scale of dryness/wetness. The classification scheme is 

based on four of the seven hydrologic features that provide a hydrologic sketch of an island:

1. Perennial stream, which is designated pR;

2. Perennial spring, which is designated pS;

3. Wetlands, which is designated wL, and 

4. Freshwater lakes, which is designated fL.

Depending upon which of these features is 

present, an island is assigned to 1 of 10 classes, where

• Class 1, in which each of the four features is 

absent, denotes a general state of dryness;

• The intermediate classes, 2, ..., 9 in which one or 

more, but not all, of the features are absent denote 

a general scaling from less dry to more wet; 

• Class 10 in which each of the four features is 

present denotes a general state of wetness. 

The states of dryness/wetness relate only to the 

surficial hydrologies of the islands.

Of the 1,000 islands:

• The hydrologic class is specified for each of the 

643 islands coded as CS; that is, the islands with 

complete hydrologic sketches; and

• The hydrologic class is specified for 35 of the 212 

islands coded PS; that is, the islands with partially 

complete sketches, but such that the relevant 

hydrologic features (pR, pS, wL, and fL) are each 

scored; whereby

• The hydrologic class is specified for a total of 678 

(= 643 + 35) islands; this leaves

• 322 (= 1,000 – 678) islands whose hydrologic 

classes could not be ascertained (‡).

The definitions of the hydrologic classes in terms 

of the presence or absence of the four hydrologic features (pR, pS, wL, and fL) and the distribution of 

islands over the hydrologic classes are given in table 

24.

With respect to table 24:

• Classes 2, 4 and 6 entail combinations of three, 

two, and four hydrologic features, respectively, 

and

• Within classes 2, 4 or 6, each combination of features is accorded equal weight; that is, the order in 

which the combinations are presented does not 

imply any increase or decrease of wetness or dryness.

The global distribution of the islands identified 

as being of the extremal hydrologic classes 1 (dry) and 

10 (wet) is shown in figure 38.

Summary

The island coverages of the 17 Environmental 

parameters are summarized in table 25.
Primary Island Set 83 Base modified from U.S. Geological Survey digital data, Gall's Sterographic Cylindrical projection, scale varies with latitude

0° 10°W

80°N

20° 30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140° 150° 160° 170°W 180°

70°60°50°40°30°20°

10°N

0°

10°S

20°30°40°50°60°70°

80°S

170°E 160° 150° 140° 130° 120° 110° 100° 90° 80° 70° 60° 50° 40°E 10°E 20° 30°E

EXPLANATION

Hydrologic class

1 (dry)234

5678

910 (wet)Unspecified

Figure 38. Global distribution of islands per hydrologic class.
84 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Table 25. Island coverage, by environmental parameter

Parameter

Islands

Specified

A

Inapplicable

C

Covered

A+C

Unspecified

B

Total

A+B+C

Local meteorology

Observation code 1,000 0 1,000 0 1,000

Station elevation for precipitation 184 0 184 816 1,000

Length of record of precipitation 224 0 224 776 1,000

Mean annual precipitation 418 0 418 592 1,000

Station elevation for temperature 237 0 237 763 1,000

Length of record of temperature 243 0 243 757 1,000

Mean annual temperature 331 0 331 669 1,000

Tropical / subtropical climate markers

Mangroves 690 0 690 310 1,000

Coral reefs 979 0 979 21 1,000

Palms 995 0 995 5 1,000

Tropical peat 984 0 984 16 1,000

Temperate climate markers

Seasonal snow / ice 948 0 948 52 1,000

Sphagnum peat 953 0 953 47 1,000

Subpolar / polar climate markers

Permafrost 981 0 981 19 1,000

Permanent snow / ice 989 0 989 11 1,000

Score indicating scale of glaciation 963 0 963 37 1,000

Wetness / dryness

State 678 31 678 322 1,000
Supplemental Island Sets A and B 85

SUPPLEMENTAL ISLAND SETS A AND B

As noted above, the Supplemental Island Set A 

consists of the following:

• Those islands that were extracted from the Primary Island Set in the course of refining that set, 

and

• Islands for which values of the elevations of their 

highest peaks could not be determined (‡), a shortfall that excluded the islands from having been in 

the Primary Island Set.

As also noted above, the Supplemental Island 

Set B consists of lagoonal atolls; dry-lagoon atolls, particularly raised atolls, were defined to be within the 

sample space for selecting islands to form the Primary 

Island Set.

Relative to the eight categories over which the 

parameters of the Primary Island Set are distributed 

(table 1):

• The 14 parameters that describe the 386 islands in 

the Supplemental Island Set A, and

• The 17 parameters that describe the 368 islands in 

the Supplemental Island Set B

are distributed over five of the eight categories; the 

three empty categories for both Supplemental Island 

Sets are Historical, Hydrologic, and Environmental 

(table 26).

With respect to the Supplemental Island Sets A 

and B, the island coverages by their parameters and the 

information sources of the alpha/numeric values of 

their parameters are given in tables 27 and 28, respectively.

Among the parameters that describe the islands 

that belong to the Supplemental Island Sets A and B of 

which 12 are common to both sets. In Supplemental 

Island Set A, the parameter “Area of an Island” is, in 

effect, the land area of an island. In Supplemental 

Island Set B, the term “Land” is used to distinguish the 

area of an island, effectively the sum of the areas of the 

islets forming the island, that is, from the area of the 

atoll’s lagoon.

The 12 parameters that are common to Supplemental Island Sets A and B are, with one exception, a 

subset of the parameters that describe the islands of the 

Primary Island Set. The parameters of the subset have 

the same frame of reference relative to each of the three 

island sets. For example, the island names are the official names reported by the U.S. Board on Geographic 

Names, latitudes and longitudes are expressed to the 

nearest hundredth degree, and areas and elevations are 

expressed in square kilometers and meters, respectively. The islands in Supplemental Island Sets A and B 

are geologically characterized by geologic class, 

whereas the islands in the Primary Island Set are geologically characterized by geologic class and geologic 

species; that is, by geologic type.

Apart from “Land area of an Island,” the physiographic parameters that describe the Supplemental 

Island Set B islands are unique to the set. “Lagoon 

Area” and “Lagoon Depth” are expressed in square 

kilometers and meters, respectively.

Detailed accounts of the island coverages by the 

parameters that describe Supplemental Island Sets A 

and B islands are listed in tables 29 and 30, respectively.

Table 26. Distributions of Supplemental Island Sets A 

and B parameters, by category

[f, frequency; cf, cumulative frequency]

Count Category

Set A Set B

f cf f cf

1 Designation 2 2 22

2 Historical 0 2 02

3 Geographic 7 9 79

4 Physiogrphic 2 11 5 14

5 Geologic 2 13 2 16

6 Hydrologic 0 13 0 16

7 Economic 1 14 1 17

8 Environmental 0 14 0 17
86 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Table 27. Parameters of Supplemental Island Set A

Count

Parameter description

Island 

covered

Information

Cum. Category source

Designation

1 1 Island name 386 L

2 2 Island ID number per a specific geophysically based 

sequential order of the islands

386 N1

Geographic

3 1 Island latitude 386 L

4 2 Island longitude 386 L

5 3 Oceanic region in which an island is located 386 N1

6 4 Oceanic subregion in which an island is located 386 N1

7 5 Island group to which an island belongs 386 L

8 6 Code that indicates whether or not island group name 

found in geographic literature

386 L

9 7 Island subgroup to which an island belongs 386 L

Physiographic

10 1 Area of an island 386 L

11 2 Elevation of highest peak 139 L

Geologic

12 1 Lithospheric plate 386 N1

13 2 Geologic class 386 N1

Economic

14 1 Sovereignty 386 L
87

Table 28. Parameters of Supplemental Island Set B

Count

Parameter description

Island 

covered

Information

Cum. Category source

Designation

1 1 Island name 368 L

2 2 Island ID number per a specific geophysically based 

sequential order of the islands

368 N1

Geographic

3 1 Island latitude 368 L

4 2 Island longitude 368 L

5 3 Oceanic region in which an island is located 368 N1

6 4 Oceanic subregion in which an island is located 368 N1

7 5 Name of island group to which an island belongs 368 L

8 Code that indicates whether or not island group name 

found in geographic literature

368 L

9 Island subgroup to which an island belongs 368 L

Physiographic

10 1 Number of islets 148 L

11 2 Number of passes 59 L

12 3 Land area of an island 132 L

14 4 Lagoon area 99 L

12 5 Lagoon depth 111 L

Geologic

15 1 Lithospheric plate 368 N1

16 2 Geologic class 338 N1

Economic

17 1 Sovereignty 368 L
88 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Table 29. Island coverage, by parameters of Supplemental Island Set A

Parameter

Islands

Specified

A

Inapplicable

B

Covered

A+B

Undetermined

C

Total

A+B+C

Designation

Island name 386 0 386 0 386

Island ID per the Alisida 386 0 386 0 386

Geographic

Island latitude 386 0 386 0 386

Island longitude 386 0 386 0 386

Oceanic region 386 0 386 0 386

Oceanic subregion 386 0 386 0 386

Island group name 386 0 386 0 386

Code on island group names 386 0 386 0 386

Island subgroup 386 0 386 0 386

Physiographic

Area of an island 386 0 386 0 386

Elevation of highest peak 386 0 386 0 386

Geologic

Lithospheric plate 386 0 386 0 386

Geologic class 386 0 386 0 386

Economic

Sovereignty 386 0 386 0 386
89

Table 30. Island coverage, by parameters of Supplemental Island Set B

Parameter

Islands

Specified

A

Inapplicable

B

Covered

A+B

Undetermined

C

Total

A+B+C

Designation

Island name 368 0 368 0 368

Island ID (identification) per the Alisida 368 0 368 0 368

Geographic

Island latitude 368 0 368 0 368

Island longitude 368 0 368 0 368

Oceanic region 368 0 368 0 368

Oceanic subregion 368 0 368 0 368

Island group name 368 0 368 0 368

Code on island group names 368 0 368 0 368

Island subgroup 114 254 368 0 368

Physiographic

Number of islets 148 0 148 220 368

Number of passes 59 0 59 309 368

Land area of an island 132 0 132 236 368

Lagoon area 99 0 99 269 368

Lagoon depth 111 0 111 257 368

Geologic

Lithospheric plate 368 0 368 0 368

Geologic class 338 0 338 30 368

Economic

Sovereignty 368 0 368 0 368
90 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

WINDOWS ON THE PRIMARY ISLAND SET

The descriptions of the islands in the Primary 

Island Set may be viewed through various “windows.” 

The Primary Island Set, which is, in effect, a matrix of 

1,000 rows (islands) and 122 columns (parameters), is 

partitioned into 13 “windows,” which are noted as 

W–1, ..., W–13. Each window, except W–13, is a 

matrix of 1,000 islands (rows) and a limited number of 

parameters (columns). The 13th window, “Names of 

Island,” is shaped somewhat differently from the other 

windows in that the number of rows (island names) 

exceeds 2,000. 

The various windows on the Primary Island Set 

are summarily listed in table 31.

Each window on the Primary Island Set provides 

a distinct description of the 1,000 islands. The distinctness of the descriptions derives from two aspects of the 

windows:

• The particular set of parameters used to describe 

the islands, and

• The particular ordering of the islands, which is 

either alphabetic, by island name, or sequentially, 

by island ID per the Alisida.

Of the 122 parameters that collectively characterize the islands, several parameters are common to 

some of, but not all, the windows; the following are 

common to windows W–1, ..., W–12:

• The official name of the island;

• The island ID number per the Alisida;

• The latitude of the island;

• The longitude of the island, and

• The oceanic region in which the island is located.

Except “the oceanic region in which the island

 is located,” the parameters are common to window 

W–13.

Maps of the islands, coupled with some general 

information about the islands, are given in Appendix G.

Table 31. Windows on the Primary Island Set

Window Description

Number

Islands

(rows)

Parameters

(columns)

W–1 Basic information 1,000 16

W–2 Historical information 1,000 13

W–3 Geographic information 1,000 11

W–4 Physiographic information 1,000 20

W–5 Topologic information 1,000 19

W–6 Geophysical information 1,000 27

W–7 Geologic neighbors 1,000 17

W–8 Demographic information 1,000 20

W–9 Geographic–geologic–sovereignty affinities 1,000 17

W–10 Ports and airports 1,000 22

W–11 Meteorologic information 1,000 17

W–12 Climatic information 1,000 23

W–13 Island names 2, 148 7
References Cited 91

REFERENCES CITED

Brown, L.A., 1950, The story of maps: Boston, Little Brown 

and Company, 397 p.

Defense Mapping Agency, 1988, World port index: Washington, D.C., Hydrographic/Topographic Center Publication 150, 278 p.

Emery, K.O., and Aubrey, D.G., 1991, Sea levels, land levels, and tide gauges: New York, Springer–Verlag, 237 p.

International Civil Aviation Organization, 1992a, Summary 

and Explanation, v. 1 of Airport characteristics data 

bank: Montreal, (International Civil Aviation Organization), 72 p.

———1992b, Africa–Indian Ocean Region, v. 2 of Airport 

characteristics data bank: Montreal, Canada, 193 p.

———1992c, Caribbean and South American Regions, v. 3 

of Airport characteristics data bank: Montreal, Canada, 

221 p. 

———1992d, European Region, v. 4 of Airport characteristics data bank: Montreal, Canada, 572 p.

———1992e, Middle East and Asian Regions, v. 5 of Airport characteristics data bank: Montreal, Canada, 277 p.

———1992f, North Atlantic, North American and Pacific 

Regions, v. 6 of Airport characteristics data bank: Montreal, Canada, 255 p.

MacArthur, R.H., and Wilson, E.O., 1967, Island biogeography: Princeton, Princeton University Press, 203 p.

Mandlebrot, B.B., 1975, Stochastic models for the Earth's 

relief—The shape and the fractal dimension of the 

coastlines, and the number–area rule for islands: Washington, D.C., Proceedings of the National Academy of 

Sciences, v. 72, p. 3825–3828.

Menard, H.W., 1986, Islands: New York, Scientific American 

Books, Inc, 230 p.

Motteler, L.S., 1986, Pacific island names: Honolulu, Bernice P. Bishop Museum Miscellaneous Publication 34, 

91 p.

Nunn, P.D., 1994, Oceanic islands: Oxford, United Kingdom, Blackwell, 413 p.

Richardson, L.F., 1961, The problem of contiguity—An 

appendix to the statistics of deadly quarrels, in Rapoport, Anatol, von Bertalantfly, Ludwig, and Meier, R.L., 

eds., General systems: v. 6, p. 139–187.

Sharp, Andrew, 1985, The Discovery of the Pacific Islands: 

Westport, Conn., Greenwood Press, 259 p.

Strahler, A. N., 1952, Hypsometric (area-altitude) analysis of 

erosional topography: Bulletin of the Geological Society of America, v. 63, p. 1,117–1,142.

Wilson, J.T., 1954, The development and structure of the 

crust, chap. 4, in Kuiper, G. P., ed., The Earth as a 

planet: Chicago, Chicago University Press, p. 138–214.
92 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

ABBREVIATIONS AND NOTATION

The abbreviations and notation specific to each 

of the windows on the Primary and Supplemental 

Island Sets are given above precceding each of the windows given by the Tables 34, 37, 40, 43, 46, 49, 52, 55, 

58, 61, 64, 67 and 70. A full account of the abbreviations and notation used throughout this report are listed 

below in table 81.

Table 32. Full account of abbreviations and notations

A Arc class C-11 Continental shield/platform Dimen. Dimension

A-1 Arc orogenic C-2 Continental structural block Dist. Distance

A-2 Arc outer arc C-3 Continental margin–composite Distr. District

A-3 Arc carbonate/volcanic C-4 Continental margin–

 igneous/metamorphic

DU Dutch

A-4 Arc carbonate C-5 Continental margin–volcanic E. Eastern

A-5 Arc volcanic/mafic C-6 Continental margin–

 sedimentary

Ea Eurasia

AC Other administrative center C-7 Continental margin–carbonate EA Eurasian

Af Africa C-8 Continental margin–

 depositional

Effect. Effective

AF African C-9 Continental orogenic–

 cordilleran

Elev. Elevation

AG Aegean C.C. Clear customs Exped. Expedition

AM American CA Canadian fL Freshwater lake

An Antarctica Carib. Caribbean FN Former name

AN Antarctic CB Caribbean FR French

AR Arabian CB. Coastal (breakwater) Geog. Geographic

Arch. Archipelago CL Climatic Geol. Geologic

Atl. Atlantic Clim. Climatic GF Other government facility

AU Australian CN Coastal (natural) Gl Glaciation

Aus. Australia CN Conventional name Gp. Group

bL Brackish water lake CO Cocos Gtr. Greater

BR British Conc. Concentration Gyra. Gyration

C Continental class Cont. Continent H1 Low island

C(1) Compactness 1 Cr Coral reef H2 Lowland

C(2) Compactness 2 CS Complete sketch H3 Rolling terrain

C(3) Compactness 3 Cum. Cumulative HI Historic

C-1 Continental tectonic block C ̊ Degree centigrade High. Highest

C-10 Continental orogenic–Alpine deg. degree HN Historical name
Abbreviations and Notation 93

HO Holocene NC National capital PA Pacific

hr. Hour Ne. Northeastern Pac. Pacific

HY Hydrologic NG New Guinea Perim Perimeter

I. Inner No. Number Pf Permafrost

IA Indian-Australian Nw. Northwestern PH Philippine

ID Identification NZ Nazca pH Prior to Holocene

Ind. Indian O Oceanic class Pl Palm

Indo. Indonesia O-1 Oceanic carbonate bank/ridge PO Portuguese

Is. Islands O-2 Oceanic non-volcanic in an

 atoll

pR Perennial river

Kep. Kepulan O-3 Oceanic makatea /

 no volcanic exposed

Proj. Projection

King. Kingdom O-4 Oceanic carbonate / volcanic PS Partial sketch

km Kilometer O-5 Oceanic volcanic / mafic pS Perennial spring

L Large O-6 Oceanic volcanic in an atoll PT Precipitation and temperature

L Length O-7 Oceanic makatea /

 volcanic exposed

Q. Queen

Lat. Latitude O-8 Oceanic plateau volcanic R Radius

Litho. Lithospheric O. Outer RB River (basin)

Long. Longitude Obs. Observations Rep. Republic

M Medium Oc. Ocean Res Reservoir

m Meter ON Official name RN River (natural)

Malay. Malaysia OR Open roadstead RS Research station

MC Metro center P Positional Rw Runway

Med. Mediterranean P Precipitation S Small

Mg Mangrove P.I. Permanent ice / snow S. Southern

mm Millimeter P1 Knob S.A. South America

MS Meteorologic station P2 Conical terrain S.I. Seasonal ice / snow

N No P3 Hill S.P. Sphagnum peat

N. Northern P4 Dome SA South American

N.A. North America P5 Ridge SC Scotia

N1 Basinal P6 Hills Se. Southeastern

N2 Valley P7 Blocky Sov. Sovereignty

NA North American P8 Mountain SP Spanish

Table 32. Full account of abbreviations and notations—Continued
94 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Spon. Sponsorship TU Turkish ‡ Unsuccessful search

sq. Square USBGN United States Board on 

 Geographic Names

# Not determined due to lack 

 of resources

sR Seasonal river USDMA United States Defense

 Mapping Agency

• Applies

sS Seasonal spring V Very small % Percent

Sta. Station V Virtual ∪ Logic operator–union

Str. Strait Vlc Volcanism ⊃ Logic operator–subset

Sw. Southwestern W Width α Islands on continental margin

T Temperature W. Western β Islands on spreading center

T.P. Tropical peat W/D Wetness / dryness δ Islands on seamounts

T1 Monocline wL Wetlands ε Islands on carbonate banks

T2 Tabular terrain Y Yes γ Islands within an island arc

T3 Apron Z. Zemlya ξ Islands on continental blocks

Tr. Trend † Not applicable

Trop. Tropical * Information not adequate for

 for further detail

Table 32. Full account of abbreviations and notations—Continued
Glossary 95

GLOSSARY

Foreign Terms

Apart from island names, very few foreign words are 

used (table 33).

Technical Terms

Aquifer. A body of rock sufficiently permeable to conduct ground water and to yield economically significant quantities of water to wells and springs. 

See Spring.

Archipelago. Group of islands in close proximity to 

one another, generally bearing a geologic relation. 

The word derives from ‘pelagus’ (Greek for principal sea), and was initially used in reference to the 

Aegean Sea.

Atoll. Especially an annular coral ring that has as its 

foundation an extinct, submerged seamount. 

Found only in tropical waters. Morphologically, 

and thereby more generally, any annular ring in 

tropical waters on or off the Continental Shelf. 

See Continental Shelf.

Brackish water. An imprecise term that refers to 

water with salinity between that of normal seawater and normal freshwater.

Coefficient of compactness. A measure on the range 

(0,1) of the degree an enclosed planar body is as 

broad as it is wide relative to a circle for which the 

coefficient of compactness equals one (1). A circle 

is the most compact form of a two-dimensional 

object. See Appendix B.

Coefficient of concordance. A measure on the range 

(0,1) of the degree of agreement which two or more 

individuals judge an object to have a specific quality. See Appendix C.

Coherence. Implies a degree of uniformity in terms of 

aspects or measures among geophysical features, 

phenomena, or observations over broad spans of 

time or space.

Constructive margin. Boundary between intersecting 

lithospheric plates where, owing to the upwelling 

of passive magma, an area of new crust is being 

added to the Earth’s surface. See Lithospheric 

plate.

Continental Shelf. Near shore, relative flat portion of 

the continental slope. See Continental slope.

Continental slope. Subsurface continent/ocean interface.

Table 33. Dictionary

Word Foreign language English

Ada Turkish Island

Alto Spanish Height

Ayios Greek Saint

Bahia Spanish Bay

Cabeco Portugese Hilltop

Cerro Spanish Hill

Dake Japanese Hill

Do Korean Island

Gora Russian Mountain

Gunto Japanese Island Group

Gunung Indonesian Mountain

Jima Japanese Island

Kepulan Indonesian Archipelago

Mont French Mountain

Monte Italian Mountain

Monte Portugese Mountain

Monte Spanish Mountain

Morne French Hill

Pic French Peak

Picco Italian Peak

Pico Spanish Peak

Piton French Peak

Retto Japanese Archipelago

San Japanese Mountain

Shima Japanese Island

Shoto Japanese Archipelago

Take Japanese Mountain

Yama Japanese Mountain

Zemlya Russian Land
96 HABITAT AND ENVIRONMENT OF ISLANDS Primary and Supplemental Island Sets

Convergent margin. Boundary between intersecting 

lithospheric plates, where the plate of lesser density is being subducted under the plate of higher 

density. See Lithospheric plate.

Coral. Any of a a large group of bottom-dwelling, 

sessile marine invertabrate organisms that belong 

to the class Anthozoa (phylum coelenterata) found 

in intertropical waters.

Coral Reef. A mound or ridge of in-place coral colonies and accumulated skeletal fragments, carbonate sand, and limestone that result from organic 

secretion of calcium carbonate that lithifies colonies and sand. See Coral.

Effective radius. The radius of a circle whose area 

equals that of an arbitrary two-dimensional object.

Ellipticity. A measure of the geometric flattening of a 

prolate ellipsoid, which is defined as the ratio of the 

difference between the prolate ellipsoid’s largest 

and smallest radii to its largest radius.

Freshwater. Water that contains only small quanitities 

of dissolved minerals. 

Geoid. Hypothetical surface of the Earth that serves as 

a reference for the measurement of dry-land 

heights and oceanic depths.

Great circle. A circle on the Earth’s surface, the plane 

of which passes through the center of the Earth.

Hypsometric curve. Functional relation between the 

area of a feature of the Earth’s surface and its 

height or depth above or below a given datum.

Hypsometry. Measure of height or depth, generally in 

relation to sea level. 

Island. A body of land surrounded by water. By definition, all dry-land fragments of the Earth are 

islands. Generally, the word ‘island’ is used in 

reference to dry-land fragments whose areas are 

less than that of Antarctica, which is the smallest 

“continent.”

Lake. An inland body of standing water that occupies 

a depression in the Earth’s surface of sufficient size 

and depth to prohibit growth of nonsubaqueous 

plants, except, perhaps, near shore.

Latitude. Angular distance of a point on the Earth’s 

surface north or south of the equator.

Lithosphere. Earth’s rigid surface layer that floats on 

the weak plastic layer, the asthenosphere. The 

depth of the lithosphere is in the range of (0 – 100 

km), which tends to vary as the square root of the 

age of the crust.

Lithosheric plate. Portion of the lithosphere; plate 

boundary marked by seismic activity. See Lithosphere.

Longitude. Angular distance between the plane of a 

given meridian through any point on a sphere or a 

spheroid and the plane of an arbitrary meridian 

selected as a line of reference.

Mangroves. Common name for various shrubs and 

trees of the families Rhizophoraceae, Verbenaceae, 

Sonneratiaceae, and Arecaceae (Palmae). Mangroves grow as dense thickets or forests along tidal 

estuaries, and in salt marshes and muddy coasts in 

tropical and subtropical regions.

Matrix. A rectangular array of alphanumeric information.

Meridian. An imaginary line on the Earth’s surface 

formed by a plane that intersects the Earth at right 

angle to any parallel.

Moment of inertia. A measure of the "resistance" of a 

rigid two-dimensional plate of unit density to rotation by a unit force.

Palms. Common name for any flowering plant of the 

order Arecales and of the single family in the order 

Arecaceae (Palmae). Palms are mainly found in 

tropical and subtropical regions. Among the various species are Phoenix dactylifera (date palm) 

and Cocos nuicifera (coconut palm). 

Parallel. An imaginary line on the Earth’s surface 

formed by a plane that intersects the Earth normal 

to the polar axis. The parallel whose plane bisects 

the Earth is referred to as the “equator.”

Peat. An unconsolidated deposit of semicarbonized 

plant remains in a water-saturated environment and 

of moisture content in excess of 75 percent.

Perennial. Refers to river or spring flow being continuous throughout the year.

Permafrost. Any soil, subsoil, or other surficial 

deposit that occurrs in arctic, subarctic, or alpine 

regions at a variable depth beneath the Earth’s 
Glossary 97

surface in which below-freezing temperatures exist continuously over a broad expanse of time.

Positional distance. The great circle distance between 

two points that marks the location of two islands on 

the Earth’s surface. See Great circle.

Projection. Any well-defined system of lines drawn 

on a plane surface to represent the corresponding 

system of parallels and meridians in reference to 

the Earth’s surface. See Parallel and Meridian.

Radius of gyration. The distance from a reference 

point to a point where if the area of a two-dimensional body was concentrated, then the moment of 

inertia of the concentrated area would equal the 

moment of inertia of the distributed area of the 

body. See Moment of inertia.

River. A body of running water that moves by gravity 

to progressively lower levels in relative narrow but 

well-defined channel on the surface of the ground. 

Herein, “river” is synonymous with “stream.”

Salt water island. An island surrounded by seawater. 

Islands within freshwater bodies or within deltas of 

rivers that discharge to the sea are excluded from 

the study.

Scale. The ratio between linear distance on a map and 

the corresponding distance on the surface being 

mapped.

Seasonal. Refers to river or spring flows that occurr 

only during and following the rainy season over 

part of the year.

Shape. The spatial form of an island as reflected by its 

coastal outline.

Spring. A place where ground water flows naturally 

from rock or soil onto the land surface or into a 

body of surface water.

Subduction. Process by which one of two interacting 

lithospheric plates is forced under the other. See 

Constructive margin.

Topography. The physical surface features of a region 

considered as forming a unit.

Virtual distance. The distance equal to the positional 

distance between two islands minus the sum of the 

effective radii of the islands. See Effective radius.

Wetlands. Areas that are permanently wet or intermittently covered by water.