Geology and 

Cement Raw Materials 

of the Windy Creek Area 

Alaska

GEOLOGICAL SURVEY BULLETIN 1039-D

Geology and 

Cement Raw Materials 

of the Windy Creek Area 

Alaska

By R. M. MOXHAM, R. A. ECKHART, and E. H. COBB

INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA 

GEOLOGICAL SURVEY BULLETIN 1039-D

Description of pre-Devonian to 

Late Cretaceous geohgy, including 

three limestone deposits

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1959
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington 25, D.C.
CONTENTS

Page

Abstract- _________________________________________________________ 67

Introduction. _____________________________________________________ 67

Location of area._______-______________________________________ 68

Previous investigations,________________________________________ 68

Present investigation.__________________________________________ 68

Acknowledgments. _____________________________________________ 70

Geography _ _____________________________________________________ 70

Topography and drainage_________-_____________________________ 70

Climate....,__________________________________________________ 72

Vegetation.. __________________________________________________ 72

Accessibility. __________________________________________________ 73

General geology..__________________________________________________ 73

Pre-Devonian rocks..__--______--____-___-_-______-_____--_____ 73

Devonian system______________________________________________ 74

Devonian (?) system.___________________________________________ 78

Triassic system._______________________________________________ 79

Triassic(?) system..____________________________________________ 80

Jurassic(?) system.____________________________________________ 81

Cretaceous system.____________________________________________ 82

Cantwell formation________________________________________ 82

Quaternary system.____________________________________________ 82

Igneous rocks________________________________________________ 83

Cement raw materials..____________________________________________ 84

Limestone ____________________________________________________ 84

Deposit l_.__________________________________-_____-_-_-__ 85

Deposit 2_._______________________________________________ 87

Deposit 3_._____________________________________________ 88

Other deposits--__-________-_-_____________-_-_____-------- 91

Argillaceous materials._____-_________________-_-__-_-__----_--_ 92

Pre-Devonian rocks._______--________________--____---_-_-_ 92

Devonian system._________________________________________ 92

Jurassic(?) system._-_-_____________________---____-------_ 94

Chert-__--________:___-_______________________-______--__---- 94

Potential cement composition___________________________________ 95

Literature cited..__________________________________________________ 97

Index_____________________________________________________________ 99

ILLUSTKATIONS

PLATE 11. Geologic maps and sections of Windy Creek area, Alaska.- In pocket

Page 

FIGURE 13. Index map of south-central Alaska..-_____________________ 69

14. Fault zone in Foggy Pass _____________-___--__-_-----_-- 76

15. Northeastern part of Windy Creek area____-_-------------- 77

16. Limestone deposit 2__.__________________________________ 87

17. Headwaters of West Fork of Windy Creek-___--___-------- 89

in
IV CONTENTS

TABLES

Page

TABLE 1. Chemical requirements for type II portland cement.---_-___ 85

2. Chemical analyses of surface samples of limestone deposit 1__ 86

3. Chemical analyses of samples of limestone deposit 2...______ 88

4. Chemical analyses of samples of limestone deposit 3--._-_-__ 91

5. Summary of data pertaining to argillaceous materials.--.---- 93

6. Chemical analyses of argillaceous materials,________________ 93

7. Calculations of potential cement composition..------------- 97
INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

GEOLOGY AND CEMENT RAW MATERIALS OF THE 

WINDY CREEK AREA, ALASKA

By R. M. MOXHAM, R. A. ECKHART, and E. H. COBB

ABSTRACT

The Windy Creek area, on the south flank of the Alaska Range, is within a 

geosynclinal belt that contains clastic and calcareous rocks ranging in age from 

pre-Devonian to Late Cretaceous. The major geologic structures in the area 

are oriented parallel to the regional easterly to northeasterly trend of the 

Alaska Range. Steeply dipping folded strata of Mesozoic age occupy the southern part of the area and have been downthrown against Devonian rocks on 

the north by a major fault zone that crosses the center of the area.

Two limestone deposits of Devonian and Devonian (?) age are of adequate 

size and chemical quality for cement-manufacturing purposes. They are located 

7 and 11 miles, respectively, west of the Alaska Railroad. A third limestone 

deposit of large size but of inferior quality lies 1 mile west of the railroad. 

Argillaceous rocks, which occur in both the pre-Devonian, Devonian, and Jurassic (?) systems, are found in many parts of the area. Chert of Triassic age, 

possibly of some value as a high-silica component, occurs along the Alaska 

Railroad near Windy station.

INTRODUCTION

All the portland cement and other limestone products used by 

the construction industry in Alaska at the present time (1956) are 

imported from the continental United States. Interest has been 

shown in the possibility of local manufacture of these materials, 

particularly since the surge in construction that began in the early 

1940's.

As the principal population centers and the most highly developed transportation systems are in south-central Alaska, the search 

for suitable raw materials for cement production has been concentrated in this region, especially in the Alaska Railroad belt. Three 

general localities in the railroad belt have received consideration 

as possible sources of cement materials (Waring, 1947; Rutledge 

and others, 1953; and Moxham and Eckhart, 1956), but the Windy 

Creek area, in the northern part of the belt, has been studied in

67
68 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

more detail than the other potential sites, largely because of the 

proximity of limestone to the railroad.

The purpose of this report is to describe the principal geologic 

features of the Windy Creek area, with particular emphasis on those 

rock types of potential value in the manufacture of portland cement.

LOCATION OF AREA

The Windy Creek area is on the south flank of the Alaska Range, 

in south-central Alaska (fig. 13). The area lies across the Alaska 

Railroad and is in part within the southeastern limits of Mount 

McKinley National Park. Mount McKinley is about 70 miles southwest of the center of the area described in this report.

The limits of the Windy Creek area have been arbitrarily chosen; 

they are represented by lat*63°22' and 63°29'30" and long 148° 48' and 

149°18' (pi. 11). About 145 square miles are included in this area.

PREVIOUS INVESTIGATIONS

In 1898, G. H. Eldridge (1900) and Robert Muldrow of the IT. S. 

Geological Survey ascended Susitna River and its tributary drainage, crossed to Jack River at the east limit of the Windy Creek 

area, and traversed downstream along Jack and Nenana Rivers to 

Yanert Fork. Their brief descriptions of the rocks exposed along 

these streams were the first recorded geological observations made 

in the Windy Creek area.

The first systematic topographic and geologic survey was made 

in 1913. A party, under the direction of F. H. Moffit (1915), worked 

westward along the south flank of the Alaska Range from the Delta 

River country to Jack River, and mapped the geology on a reconnaissance scale.

In 1930 the geologic mapping of the south side of the Alaska 

Range was extended to the West Fork of Chulitna River by Capps 

(1932) who completed reconnaissance coverage of the area described in the present report.

The following year, Waring (1947) briefly examined and sampled 

four exposures of limestone between Little Windy Creek and the 

Alaska Railroad, west of Windy station, in connection with an investigation of nonmetallic minerals in the Alaska Railroad belt.

PRESENT INVESTIGATION

The present study of the Windy Creek area, for the purpose of 

investigating potential cement raw materials, began in 1947. In 

that year Cobb mapped in detail the limestones between Little 

Windy Creek and the railroad. Surface samples were collected from
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 69

PIGUKE 13. Index map of south-central Alaska showing location of Windy Creek area.

two of the larger, more accessible limestone deposits. R. E. Fellows 

of the Geological Survey made a brief field investigation in 1949 

to integrate coredrilling data, furnished by the U. S. Bureau of 

Mines, with the geological studies and to sample deposits of argillaceous materials that crop out near the railroad and in the lower 

Windy Creek basin.
70 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

Chemical analyses of the limestone samples and cores made by 

the Geological Survey and the Bureau of Mines, respectively, in 

1947-49 indicated that the principal limestone deposits in the area 

east of Little Windy Creek are not of uniform chemical character. 

Although this condition might not preclude the use of restricted 

parts of the deposits for cement manufacture, it seemed desirable 

to determine whether other, more suitable limestone deposits exist 

elsewhere in the Windy Creek area. In July 1950, a brief reconnaissance of the Windy Creek drainage basin west of Little Windy 

Creek was undertaken, the principal objectives being to locate and 

sample all limestone bodies of potential commercial size and to sample the more accessible deposits of argillaceous materials. Two 

limestone deposits of adequate tonnage were mapped and sampled 

and several deposits of argillaceous materials were investigated. 

The present bulletin supersedes a brief open-file report describing 

this investigation (Moxham and others, 1951).

The geological investigations in the Windy Creek area described 

above were confined to detailed studies of relatively small portions 

of the eastern part of the area and reconnaissance surveys of the 

western part. Hence, in 1951, additional fieldwork was undertaken 

to determine more precisely the location and distribution of potential cement raw materials in the western part of the area, and, insofar as time permitted, to attempt to integrate the previous detailed studies with the areal geology. The fieldwork in 1951 was 

carried out between May 28 and July 10 by R. M. Moxham and 

R. A. Eckhart, geologists, and W. A. Bakke and R. A. Wilkens, 

field assistants. In the brief time available for this work it was 

possible only to map the major geologic units in reconnaissance fashion, and in many localities it was necessary to supplement direct 

field observations by photogeologic methods.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the courtesies extended by 

Mr. Jack West and the late Mr. John E. Carlson of Cant well, Mr. 

Claude Rogers of the Alaska Road Commission, and the Alaska 

Railroad. Chemical analyses were made by R. K. Bailey, S. M. 

Berthold, H. M. Hymen, L. E. Reichen, L. I. Shapiro, and A. C. 

Ylisidis of the Geological Survey, and by A. A. Hanks, Inc.

GEOGRAPHY 

TOPOGRAPHY AND DRAINAGE

The Windy Creek area includes parts of two physiographic divisions, the Alaska Range and the Broad Pass depression (Wahrhaftig, 1958). West of long 149°10' W. the crest of the Alaska Range
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 71

lies just south of the north boundary of the Windy Creek area. 

East of long 149° 10' W., it lies 1 to 3 miles north of the north boundary of the Windy Creek area. Despite the fact that Mount McKinley, 70 miles to the southwest, rises to 20,300 feet in altitude, the 

crest of the Alaska Range in the vicinity of the Windy Creek area 

is generally between 5,000 and 6,500 feet in altitude. The south 

flank of the Alaska Range is an interlocked mass of rugged peaks, 

sharp ridges, and U-shaped canyons. The peaks rise to altitudes of 

5,000 to 6,000 feet, and the canyon floors range in altitude from 

2,500 to 4,000 feet. Local relief is between 2,000 and 3,500 feet. 

The canyons were occupied by glaciers during the Pleistocene epoch; 

hence most of them are U-shaped, with flat floors and steep sides, 

and head in cirques. Locally the floors of the canyons are trenched 

by narrow steep-walled gorges.

The southeastern part of the mapped area is in the Broad Pass 

depression, an arcuate lowland 4 to 6 miles wide that lies along the 

south side of the central part of the Alaska Range. In the Windy 

Creek area this lowland has an average altitude of about 2,200 

feet. A belt of valleys and low passes extends across the south flank 

of the Alaska Range in a S. 75° W. direction from the north side 

of the Broad Pass depression near Windy Creek. The line of valleys and passes is eroded along the trace of a great fault (pi. 11). 

It affords easy access to the more remote limestone deposits of the 

area.

The entire Windy Creek area is drained by the Nenana River 

and its tributaries. The Nenana River flows northward to a canyon through which it crosses the Alaska Range to flow into the 

Tanana River. At the point where it enters the canyon it is joined 

from the southwest by the Jack River, which flows northward and 

northeastward through the southeastern and eastern part of the 

Windy Creek area. The two main tributaries of the Jack River 

are Windy Creek and Cantwell Creek. Cantwell Creek drains the 

southern part of the Windy Creek area, including much of the floor 

of the Broad Pass depression, and a narrow strip along the west 

margin west of Foggy Pass. Windy Creek and its tributaries drain 

the largest part of the area, including the limestone deposits.

Windy Creek heads at the crest of the Alaska Range and courses 

southeastward through a U-shaped trough to its junction with its 

west fork (hereafter referred to simply as the West Fork) in the 

central part of the mapped area. The West Fork rises in the extreme northwestern part of the Windy Creek area in a glacial basin 

at the crest of the range and flows in a southerly and easterly direction through a glacier-scoured valley to its mouth. Beyond its 

junction with the West Fork, Windy Creek flows in an easterly

504834 O 59 2
72 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

direction across part of the Broad Pass depression to enter the 

Jack River.

Numerous boulders and a generally steep gradient prevent the 

use of boats of any kind on Windy Creek and the West Fork. During periods of high water in the spring and immediately after rainstorms in the summer months, Windy Creek below its junction with 

the West Fork may be difficult to ford on foot. Crossing during 

most of the rest of the summer, however, can be made without 

trouble.

CLIMATE

No weather records are kept at any locality in the Windy Creek 

area, but the data collected by the Civil Aeronautics Administration (U.S. Weather Bureau, 1955) at Summit, a short distance south 

of the area, give some indication of the climatic conditions that 

prevail in this region. The average annual temperature at Summit 

is 25°F with the average for the period June through August being 50°F and for the period December through February 5° F. 

Total precipitation is about 22 inches; an annual average of 113 

inches of snowfall was recorded during the period 1950-54. Freezing temperatures may ordinarily be expected as late as May and 

as early as August, with the first ice occurring usually in October 

and the breakup in May.

The average seasonal temperatures in the Windy Creek area, as 

elsewhere in central Alaska, range widely, from the fifties in summer to the minus tens (°F) in winter. The Alaska Range forms 

a barrier across the path of the northward flow of Pacific air up 

the Susitna-Chulitna lowland, and as the moisture-laden air is 

driven upward, the seaward flank of the range receives an abnormal 

amount of precipitation. The dissimilar growth of glaciers on 

opposite flanks of the range reflect the difference in precipitation; 

those to the south of the crest are larger in size and number. However, the report area and its immediate environs are somewhat 

anomalous in that the development of glaciers is relatively poor, 

perhaps owing to the lower average altitude of the crest of the 

range in this vicinity or to some other local topographic condition 

that controls the airflow and precipitation.

VEGETATION

Timberline in the Windy Creek area is about 2,800 feet in altitude, so that the growth of timber, mainly spruce and cottonwood, 

is restricted largely to the lowlands in the southeastern part of the 

area and to narrow strips along Windy Creek and its principal 

tributaries. The junction of Windy Creek and the West Fork
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 73

marks in general the westward extent of timber growth. Beyond 

this point, and locally above the 2,800-foot altitude, there is some 

scrubby growth, mainly cottonwood, willow, and alder. Most of 

the stream valleys below timberline are heavily overgrown with 

brush and shrubs, mostly willow and alder.

ACCESSIBILITY

The eastern part of the area is accessible by rail and air. Cantwell, in the southeastern part of the area, is 205 miles by rail from 

Anchorage and 151 miles from Fairbanks. A small airstrip at 

Cant well will accommodate single-engine planes. Flagstop airline 

connection with Anchorage and Fairbanks is available at Summit, 

7 miles by road south of Cantwell.

The eastern part of the Windy Creek area is accessible by road 

from Anchorage and Fairbanks. Two tractor trails give access to 

the valley of Windy Creek from Cantwell. One extends to the 

mouth of Windy Creek; the other runs westward to a National 

Park Service shelter cabin on Windy Creek, about 5 miles above its 

mouth. The valleys of Windy Creek and the West Fork offer no 

serious obstacle to tractor travel beyond the trail's end until the 

headwater gorges are reached.

GENERAL GEOLOGY

The area of this report is in the axial region of the Alaska 

Range geosyncline, a major arcuate tectonic element in a belt of 

subsidence that probably has been operative since early Paleozoic 

time. Sedimentary rocks in the area, predominantly clastic beds 

deposited in a marine environment, range in age from pre-Devonian 

to Late Cretaceous and are intruded by and interbedded with andesitic volcanic rocks of probable Triassic age. Granitic batholithic 

intrusives, sills, and dikes, emplaced during the Paleocene(?) orogeny, cut the sedimentary and volcanic units in the western part of 

the Windy Creek area.

PRE-DEVONIAN BOCKS

The oldest part of the geologic succession in the area mapped 

consists of pre-Devonian rocks that crop out on the south flank of 

the first ridge southwest of the junction of Windy Creek and the 

West Fork. Red, green, and buff argillite and shale are the predominant rock types and are quite dissimilar in appearance to any 

other strata observed in the report area.

On the south the pre-Devonian rocks abut the great fault zone 

that transects the entire Windy Creek area, and are upthrown
74 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

against Jurassic ( I ) strata. The brightly colored pre-Devonian 

strata dip steeply southward, apparently constituting the south 

limb of an overturned fold, as they give way in a northerly direction to rocks of Devonian age. Evidence from which to determine 

the structural relationship adjacent to the great fault zone is concealed in the report area by alluvium and by glacial and glaciofluvial deposits. Capps (1932) made observations in the Chulitna 

River area to the west that led him to conclude that the narrow 

belt of rocks that include the highly colored argillite and shale 

immediately adjacent to the fault zone definitely underlie the Devonian rocks. Capps mapped an outcrop of the pre-Devonian rocks 

sslong the north side of Foggy Pass in the Windy Creek area, but 

the present writers have shown only Devonian strata here, owing 

to the presence of conglomerate that appears to be closely akin to 

the coarse clastic sediments found in the belt of Devonian east of 

Foggy Pass. The thickness of the pre-Devonian rocks in the mapped 

area is about 1,500 feet.

DEVONIAN SYSTEM

Closely folded metamorphosed marine strata of Devonian age crop 

out in a generally eastward-trending belt across the central part of 

the Windy Creek area. The rocks consist mainly of argillite, limestone, conglomerate, graywacke, slate, greenstone, and quartzite. The 

strata are characterized by abrupt lateral and stratigraphic discontinuities, so that in most localities individual beds are neither very 

thick nor laterally persistent. In the western part of the area the 

rocks are made up chiefly of conglomerate interbedded with argillite, 

graywacke, and a little limestone. Conglomerate beds that range 

from 2 to 60 feet in thickness are found throughout the section. 

Most of them are dark colored and are composed chiefly of black 

chert, argillite, and quartz particles, ranging in size from coarse grit 

to pebbles several inches in diameter, in a siliceous matrix. Toward 

the east the clastic sediments tend to become finer in texture, limestone becomes more abundant, and some greenstone, tuff, and quartzite are found.

Most of the limestone beds are relatively thin and discontinuous. 

In a few areas they are as much as 500 feet thick, but the average 

thickness is probably nearer 50 feet. The limestones are generally 

gray or, locally, buff on weathered surfaces and black or dark gray 

where fresh. The rock is mainly very dense and fine grained in 

texture, although locally it is coarser grained where recrystallized. 

The calcareous strata have been thoroughly shattered by intense 

dynamic metamorphic action, and the rock is reticulated by calcitefilled fractures. At most places the original bedding of the lime-
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 75

stone is obscured by secondary structural features to such an extent 

that the rocks are massive.

Argillite is common in the eastern part of the area. The beds are 

brown to black and are generally thin. In many parts of the area 

the argillite has been crumpled, sheared, and intricately faulted both 

as a result of regional metamorphic action and, locally, as a result 

of stresses along the faults that bound the unit on the north and 

south.

Fossils are scarce in these strata, except for a few poorly preserved 

specimens in the limestone beds at several localities. Most of the 

fossils are sufficiently silicified to become etched in relief on weathered surfaces; very little of the freshly broken rock shows any trace 

of organic remains. Collections were made at two locations, shown 

on figure 2. The fossils consist largely of corals but also include 

stromatoporoids and bryozoa. The collections contain the following forms:

Locality

1

2

Collection

47-ACb-76

50-AMx-101 

50-AMx-102 

50-AMx-103 

50-AMx-104 

50-AMx-105

Fossil

Tryplasma sp., Amphipora sp.

Cladopora sp., pseudamplexoid coral, stromatoporoids. 

pseudamplexoid coral. 

Coenitest sp., unidentified horn coral. 

Cladopora sp., stromatoporoids. 

Coenites sp., unidentified bryozoan.

The fossil identifications were made by Jean M. Berdan, of the 

U. S. Geological Survey, who reports as follows:

Lot 47-ACb-76 differs from the other collections in containing the horn coral 

Tryplasma, which is most abundant in the Silurian but has been reported from 

the Middle Devonian of Germany (Etheridge, R., Geol. Survey of New South 

Wales, Mem. 13, p. 44, 1907). This collection also contains a block with different lithology from that containing the horn corals in which there are rodlike 

objects which appear to be Amphipora, a form of stromatoporoid occurring in 

the Middle and possibly also in the Upper Devonian. The * * * collection * * * 

was made from talus so that more than one horizon may be represented. Lots 

50-AMx-101 through 105 contain horn corals wrhich agree with the subfamily 

Pseudamplexinae described by Stumm (Geol. Soc. America Mem. 40, p. 47-48, 

1949) in possessing subcylindrical corallites with radially arranged septa, no 

fossula, and a septal dilation wrhich suppresses the dissepiments in the peripheral zone. However, this subfamily is described as containing simple corals 

only, and some of those in the material at hand appear to be weak faciculate. 

These corals are associated with the tabulate coral Cladopora and with lamellar and encrusting stromatoporoids. Twro collections contains a tabulate coral 

referable to Coenites and one an unidentified bryozoan. All these forms range 

from Silurian through the Middle Devonian but * * * similar material (from 

this area) has been identified as Middle Devonian, and this is probably the 

best age assignment possible at present.
FIGURE 14. Northwestward view across fault zone in Foggy Pass. The trace of the fault 

is marked by low scarp line in center of photo.

The structure of the rocks of Devonian age is very complex. The 

strata are intricately folded and faulted, but in general the strike 

is northeasterly and steep southerly dips predominate.

The southern extent of the Devonian strata, except where they 

are underlain by the pre-Devonian, is limited by a major fault zone 

that is perhaps the outstanding structural feature of the Windy 

Creek area. This zone cuts across the area in a northeasterly direction, following a remarkably straight trend. The trace of the fault 

is marked by springs, bogs and, locally, low scarps (figs. 14 and 15). 

The fault probably extends far beyond the limits of the report area, 

both to the east and to the southwest.

The existence of the fault zone in this area was first noted by 

Moffit (1915) who mapped a small part of it near Nenana River. 

Capps (1932) apparently was the first to recognize that the zone 

probably extended from Anderson Pass, 40 miles west of Cantwell, 

to Nenana Glacier, 35 miles east of Cantwell. He also pointed out 

topographic features that suggest its continuation beyond these 

limits. Geologic mapping in the eastern part of the Alaska Range 

(Moffit, 1912; 1954) indicates that the fault zone may extend many 

miles farther to the southeast.

In the Windy Creek area the fault zone probably is vertical or 

dips steeply to the north, dropping Jurassic(?) and Upper Cretaceous rocks on the south (downthrown) side into contact with 

Devonian strata on the north (upthrown) side.
FIGURE 15. Aerial view of northeastern part of Windy Creek area. Limestone deposit 1 is located at A. The trace of the major fault

zone between Devonian and Mesozoic rocks is discernible between points B and C.
78

The northern extent of the Devonian rocks west of Little Windy 

Creek probably is limited by another nearly vertical fault which 

has brought them into contact with younger beds of possible Devonian age. In the western part of the area, the line of displacement 

is clearly marked on the aerial photo (fig. 15) by northeastwardto eastward-oriented drainage, and an alinement of similarly oriented 

passes extends from a point at least several miles beyond the western 

limit of mapping eastward almost to the junction of Windy Creek 

and the West Fork. Eastward from this junction the structural 

relation is more obscure and the location of the fault between Windy 

and Little Windy Creeks has accordingly been questioned on figure 2. 

East of Little Windy Creek the aerial photos show no displacement 

of the Triassic rocks that presumably overlie the Devonian section, 

but whether the Devonian rocks are faulted beneath the Triassic is 

open to question. Indeed, the location of the Devonian-Triassic 

contact itself is questionable, as noted in the discussion of the Triassic system (p. 80).

Because of the complex folding and faulting, the thickness of the 

Devonian rocks can only be estimated to be about 3,000 feet.

DEVONIAN(P) SYSTEM

North of, and in fault contact with, the Devonian rocks west of 

Little Windy Creek is a succession of reddish-weathering, folded 

and metamorphosed thin-bedded shaly limestone, argillite, graywacke, and shale. This sequence is here referred to as of Devonian (?) age although no fossil evidence of this age has been found. 

East of Little Windy Creek recognized Devonian rocks are unconformably( ?) overlain by sedimentary rocks of Triassic age. On 

the basis of the lithologic dissimilarity of the reddish-weathering 

sequence and the Triassic section and of the structural relationship 

of the reddish-weathering strata to Devonian rocks west of the 

Windy Creek area, an age designation of Devonian (?) seems most 

appropriate.

The Devonian (?) rocks crop out in the headwaters of the Windy 

Creek and the West Fork drainage basins. In contrast to the rocks 

of the accepted Devonian, the Devonian (?) strata appear to be 

nearly free of conglomerate and contain a greater percentage of 

calcareous rocks. The strata consist of closely folded, metamorphosed sedimentary beds, primarily limestone, graywacke, argillite, 

and shale. These beds, with the exception of the more massive limestones, are generally dark colored where fresh, characteristically 

weathering to shades of reddish brown. The limestone generally 

tend to be argillaceous and with one notable exception are thin bedded, locally schistose, strata.
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 79

The most impressive lithologic unit of the Devonian (?) strata 

is a massive limestone that crops out in an eastward-trending belt 

across the headwaters of the West Fork. It is quite persistent 

laterally along the strike, extending for at least 20 miles west of 

the West Fork and two miles eastward. The limestone is blue gray 

to black, is locally banded, and weathers to a light gray. Most of 

it is very dense and has a fine-grained texture. In some localities 

the rock is quite hard and breaks with a conchoidal fracture. Calcite reticulation is abundant.

Although wide variations occur in the attitude of individual beds 

the limestone body as a whole probably stands nearly vertical. The 

limestone attains a maximum thickness of about 2,600 feet in the 

valley of the West Fork; its outcrop thins markedly to the east 

and somewhat less so to the west.

North of the massive limestone and overlying it are interbedded 

limestone, argillite, and shale, which dip steeply to the north. Similar rocks, closely folded and faulted but generally dipping steeply 

to gently southward, lie south of the massive limestone; they probably belong to the same stratigraphic sequence as those north of the 

massive limestone. If this interpretation is correct, the major structural feature of the Devonian (?) strata in the headwaters of the 

West Fork is an eastward-trending anticline, although other complex folds are superimposed upon the major structure. The axis of 

the structure follows the outcrop of the massive limestone so that 

this geologic unit may represent both limbs of a closely compressed 

fold.

Only a rough estimate of the thickness of the Devonian (?) rocks 

can be made, but it appears that as much as 8,000 feet may be 

present in the western part of the Windy Creek area. The massive 

limestone is probably about 1,300 feet thick stratigraphically.

TRIASSIC SYSTEM

East of Little Windy Creek, rocks of Triassic age overlie the 

Devonian. Here the lower part- of the Triassic section consists of 

1,000 to 2,000 feet of argillite, limestone, conglomerate, chert, greenstone, and slate which strike in a northeasterly to easterly direction 

and dip steeply both to the north and to the south. The lithology 

of the lower part of the section is quite similar to the underlying 

rocks of Devonian age, so that the position of the boundary between the systems is open to question. The location of the boundary 

shown in plate 11 is based on the evidence of fossil collections 

47-ACb-76 and 47-ACb-78 (p. 80) and the predominance of greenstone in the younger system. The stratigraphic and structural relationships of the Triassic rocks with the underlying rocks of

504834 O 59 3
80 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

Devonian age are not clear, but the boundary is probably an unconformity.

No Triassic rocks had previously been mapped in this part of 

the Alaska Range, but they had been seen in adjacent areas. Near 

the crest of the range north and west of the Windy Creek area 

Capps recognized greenstone, slate, and chert between known Devonian rocks and overlying Cretaceous rocks, but in the absence of 

any evidence to the contrary he included them with underlying 

strata of Devonian age. Limestone of Triassic age interbedded with 

greenstone and other volcanic rocks has been found elsewhere on 

the south flank of the range. On the West Fork of Chulitna River, 

about 20 miles southwest of the Windy Creek area, Ross (1933, p. 

298) mapped limestone and argillite of Triassic age which overlie 

rocks of Permian age, and in the Valdez Creek area, about 40 miles 

to the east, Moffit (1915, p. 33) found limestone of Triassic age 

interbedded with greenstone.

Greenstone, chert, and phyllite lie unconformably beneath the 

Cantwell formation in the headwater of Yanert Fork, northeast of 

the Windy Creek area. Apparently these rocks are similar in 

lithology to those that underlie the Cantwell formation west of 

Nenana River; they are probably Triassic in age (Wahrhaftig, 

1958, pi. 4).

In 1947 E. H. Cobb made two collections of fossils from a limestone bed near the west end of the ridge between Bain and Windy 

Creeks. The identifications given below are by Ralph W. Imlay:

Locality

3

Collection

47-ACb-78 

47-ACb-79

Remarks

Contains the pelecypods Megalodus(1) and Mysidia 

which are characteristic of the Upper Triassic. 

Contains a belemnite that is definitely Mesozoic but not 

well enough preserved to identify generically.

TRIASSIC (?) SYSTEM

The foregoing description of Triassic rocks outside of the Windy 

Creek area indicates that greenstone and other volcanic rocks are 

common constituents of the Triassic strata. In the area of this 

report, the narrow belt of predominantly sedimentary rocks of Triassic age is overlain on the north by a thick sequence of andesitic 

and basaltic greenstone sills and extrusive rocks that occupy the 

northeastern part of the mapped area and have been designated as 

Triassic (?) in age. In general they dip to the north at a moderate 

angle, perhaps averaging 20°-30°.
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 81

Altered greenstone extrusive masses interbedded with tuffs crop 

out in the area west of Cantwell. Their stratigraphic relationship 

to the Jurassic rocks on the north has not been established, as the 

bedding of both units appears to be nearly vertical in the contact 

areas. In the extreme southeastern part of the greenstone outcrop 

area, some of the flows when viewed from a distance appear to dip 

gently to the south and to strike northeastward. They are tentatively correlated with the Triassic (?) greenstone that crops out in 

the northeastern part of the area.

JURASSIC (?) SYSTEM

A belt of steeply dipping metamorphosed sedimentary strata, tentatively assigned a Jurassic (?) age, crops out between the major 

fault zone that trends northeastward across the central part of the 

area and the intrusive and volcanic rocks which border the Windy 

Creek area on the south. In the western part of the area the predominant constituents are argillite and slate, with some conglomerate, which are cut by felsic dikes and sills, although the igneous 

rocks are not abundant. The slate and argillite are mostly black; 

the conglomerate is dark brown to black; it is composed chiefly of 

black chert, dark argillite, and white quartz pebbles set in a dark 

brown matrix. In the eastern part of the Jurassic(?) belt, the 

clastic sediments become much coarser with graywacke predominating.

In most of the Windy Creek area the rocks of Jurassic (?) age 

are cut off on the north by the major fault zone, but in the extreme 

western part they are overlain by the Upper Cretaceous Cantwell 

formation. The complexity of the structure in this area obscures 

the stratigraphic relationship of the rocks of Jurassic (?) age with 

the Cantwell rocks, but there may be an angular unconformity between the Cantwell formation and the underlying strata, as found 

on the north side of the Alaska Range (Capps, 1932, p. 269).

In general the Jurassic (?) rocks strike slightly north of east and 

are closely folded, with steep dips to the north and south.

The total thickness of the Jurassic (?) system on the south side 

of the central part of the Alaska Range has been estimated to be 

as much as 5,000 feet (Capps, 1940, p. Ill), but in all probability 

only the upper 4,000 feet is present in the Windy Creek area.

No fossils have been found in the Jurassic (?) rocks in the Windy 

Creek area, and in the absence of other conclusive evidence the age 

assignment remains the same as that determined by Capps (1940, 

p. Ill); he based the age of these rocks on a relatively long range 

correlation with the argillite of known Jurassic age found near the 

West Fork of the Chulitna River.
82 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

CRETACEOUS SYSTEM 

CANTWELL, FORMATION

The Cantwell formation, a nonmarine sequence of Late Cretaceous age, has a relatively wide distribution on the south side of 

the Alaska Range in the region southwest of the area of this report. 

The belt that it occupies, however, narrows to the northeast so that 

only a small part of the lower Cantwell section, in the western 

Windy Creek area, represents the easternmost extent of the formation south of the major fault zone. The Cantwell formation in the 

Windy Creek area consists primarily of dark-colored coarse massive 

conglomerate and argillite, which are locally cut by sills and dikes 

varying widely in chemical composition. The conglomerate is composed chiefly of pebbles and cobbles of limestone, argillite, slate, 

and chert, that range in size to as much as 6 inches in diameter. 

The general trend of the beds of the Cantwell formation is N. 

60°-80°E., and their attitude is nearly vertical.

On the north the rocks of the Cantwell formation are cut off by 

the major fault zone, and to the south they are underlain by black 

argillite of Jurassic(?) age. The total thickness of the Cantwell 

formation in the Windy Creek area probably does not exceed 1,500 

feet.

No fossils were found in the rocks of the Cantwell formation in 

this area. Ten miles east of the mouth of Jack River, Moffit (1915, 

p. 48) collected fossil plants of Eocene age from shale and sandstone interbedded with conglomerate, which he considered to be 

part of the Cantwell formation. However, it is recognized that the 

Cantwell formation on the north side of the range is definitely 

older than coal-bearing sediments in that area that also are of 

Eocene age. In 1936, Capps collected fossil plants from rocks of 

the Cantwell formation on the north side of the range which were 

determined to be of Cretaceous age. Although the few fossil collections that have been made from the Cantwell formation present 

conflicting evidence, an age assignment of Late Cretaceous appears 

to be the most acceptable at the present time.

QUATERNARY SYSTEM

A detailed description of the Quaternary geology of the central 

part of the Alaska range is given by Wahrhaftig (1958).

The Pleistocene epoch marked the inception of widespread and 

intense glaciation of the Alaska Range, culminating in the accumulation of such an extent of glacial ice that only the higher peaks 

of the range protruded. The gradual wane from the last advance 

has continued into Recent time, although the remaining glaciers in
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 83

the Windy Creek area are small in comparison to the impressive ice 

flows that occupy the valleys draining the range farther west.

The glaciers not only modified the preglacial landforms; they also 

laid down deposits of glacial and glaciofluvial material in the lowland of the lower Windy Creek drainage basin. At their western 

limit the deposits are probably only a few feet thick. Eastward 

the glacial deposits thicken markedly, attaining a thickness of about 

60 feet in the Windy Creek Valley 3 miles downstream from 

the mouth of the West Fork. The full thickness of the glacial 

deposits, resting on Jurassic(?) bedrock, is well exposed at this 

locality.

In the extreme eastern part of the mapped area, about 1 mile 

west of the Alaska Railroad, travertine is being deposited by spring 

water emanating from the fault zone that limits the Devonian rocks 

on the south.

IGNEOUS BOCKS

The Triassic (?) greenstone has been described in the previous 

discussion of the bedded rocks (p. 80).

In the northwestern part of the area the Devonian (?) strata 

have been intruded by an igneous complex ranging in composition 

from medium-grained diorite to an ophitic gabbro, with the more 

mafic compositions predominating. The contact with the Devonian (?) rocks in most places is inclined steeply to the north. In the 

peripheral areas the intruded beds are cut by dikes and sills, mostly 

felsic, and the host rock is locally silicified.

In all probability more than one period of intrusion was involved, 

but the principal igneous activity of batholithic magnitude probably took place in post-Cantwell, that is, Late Cretaceous or Paleocene time. This conclusion is based upon observations made in the 

region north of the Windy Creek area, where the igneous mass cuts 

the Cantwell formation of Cretaceous age but is overlain by coalbearing strata of Eocene age. Farther west, however, large masses 

of granitic rock are overlain by rocks of the Cantwell formation, 

indicating that major intrusive activity took place in the Alaska 

Range geosyncline both before and after the deposition of the 

Cantwell formation.

In the southwestern part of the area the Jurassic (?) argillites 

and slates have been intruded by a light-gray coarse-grained quartz 

diorite. The rock has a porphyritic texture in most places, with 

euhedral orthoclase crystals as much as l1/^ inches in length. The 

contact with the host rock dips moderately to steeply southward, 

approximately parallel to the local attitude of the enclosing strata. 

This intrusion is correlated with the post-Cantwell igneous rocks 

in the northwestern part of the area.
84 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA 

CEMENT RAW MATERIALS

In order to evaluate the mineral resources of the Windy Creek 

area in relation to the problem of a cement supply, it will be necessary not only to examine the structure, lithology, size, and accessibility of the individual deposits of potential raw materials, but 

also to take into consideration their chemical composition. The 

cement industry today must manufacture a product that will meet 

exacting chemical and physical standards, so that detailed knowledge of the chemical composition of the raw materials is a fundamental requirement. Deleterious substances in any potential component may well eliminate it from further consideration, even though 

all other geologic factors pertaining to its exploitation are favorable.

The chemical restrictions that apply to the various cement raw 

materials are governed to a certain extent by the type of cement to 

be produced. The chemical requirements formulated by the American Society for Testing Materials (1950, p. 1-4) for portland 

cement type II (which is employed for general construction purposes) are given in table 1. It is possible to control cement composition in part, and within certain limits, through adjustment of 

the ratio of the raw components, adjustment of the burning time 

or temperature, or both, and the use of supplemental iron and silica 

components. However, magnesia and the alkalies, which have undesirable chemical characteristics, may require flotation or other 

special treatment to bring them within acceptable limits and therefore are usually regarded as undesirable substances as far as the 

raw materials are concerned.

As each component of the raw mix, including the fuel combustion 

residue, contributes to the composition of the end product, it would 

not be possible to arrive at an upper limit of magnesia or alkali 

content for any particular raw component that would be applicable in all instances. However, with raw components of the general 

chemical composition of those found in the Windy Creek area, an 

upper limit of magnesia content of 3 percent probably would be 

applicable to the limestone, which would ordinarily be the major 

contributor of this compound. The alkalies can be dealt with only 

in very general qualitative terms, inasmuch as they would volatilize 

to an unknown extent under actual kiln operation. The maximum 

permissible amount in the cement, according to Federal specifications (table 1), is 0.6 percent (total Na2O plus 0.658 K2O) ; this 

figure may be used as a guide in the evaluation of the ingredients.

LIMESTONE

Limestone occurs at several localities in the belt of Devonian, 

Devonian (?), and Triassic rocks that crosses the Windy Creek area 

in an eastward direction. Deposits of commercial size have been
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 85

found in three general areas: (1) between the valley of Little Windy 

Creek and the Alaska Railroad, (2) on the ridge southwest of the 

junction of the West Fork with Windy Creek, and (3) in the headwater area of the West Fork. These three principal limestone deposits in the Windy Creek area are designated as deposits 1, 2, and 3. 

Their locations are shown on plate 11.

TABLE 1. Chemical requirements for type II portland cement

[Specifications are those of the American Society for Testing Materials. Federal specifications are the same 

except that when the purchaser specifies "low alkali cement," the alkali content (NasO+0.658 K^O) shall 

not exceed 0.6 percent. All values are maximum with the exception of SiOi which is minimum]

Type II 

(percent)

SiO2 __________________________ 21.0

A12O3 ___.__..______..._.___. 6. 0

Fe8O8 -~- - - _.-------- 6. 0

MgO______________.__________ 5.0

SO8_ -- ___ 2.0

Type II 

(percent)

Ignition loss_-_-___-_____-_-_-_ 3. 0

Insoluble residue.______________ .5

Tricalcium silicate.________--_-_ 50. 0

Dicalcium silicate. ___________-__----

Tetracalcium aluminate_________ 8. 0

DEPOSIT 1

The area between Little Windy Creek and the railroad, by reason of its relative accessibility, received considerable attention during the previous investigations of the Windy Creek area. The limestone outcrops were mapped in detail by Cobb in 1947. His studies 

were devoted primarily to the most extensive deposit in this area, 

designated as deposit 1.

General description. Deposit 1, a limestone in the Devonian rocks, 

is on the south side of the ridge between Windy and Bain Creeks 

(pi. 11). The easternmost exposure of the deposit is slightly less 

than 1 mile west of the nearest point on the Alaska Railroad. The 

deposit crops out between altitudes of 2,620 and 3,190 feet, the lower 

altitude being about 500 feet above the level of the nearest point on 

the railroad. Five claims, covering the greater part of deposit 1, 

were staked in October 1948 and were acquired by the following 

year by the Northern Empire Development Co. No private development work is known to have been undertaken.

The limestone of deposit 1 is typically quite dense and has a finegrained texture. It is dark gray to black where fresh and weathers 

to lighter shades of gray and buff. The strata have been thoroughly 

shattered by intense mechanical metamorphic action, and the rock is 

reticulated with calcite-filled fractures. Where bedding is discernible the strata strike about N. 70° E. and dip 60°-70° SE., although 

many local variations are found.

Exposures of deposit 1 are found intermittently over a lateral 

(east-west) distance of about 3,200 feet. Drill holes penetrating the 

deposit indicate that it has a maximum thickness of about 600 feet 

near the midpoint between its east and west limits.
86 INVESTIGATION'S OF CONSTRUCTION MATERIALS IN ALASKA

The southward extent of the limestone is concealed by talus, glacial deposits, and vegetation, but presumably the strata are terminated on the south near the major zone of faulting which brings 

the rocks of Devonian age into contact with those of Jurassic(?) 

age. On the north the limestone is underlain by greenish to black 

calcareous schist.

Sampling. Fifteen samples were taken across exposures of deposit 1 along lines normal to the strike. Each sample consisted of 

fresh chips collected at 8-inch intervals. Locations of the samples 

are shown on plate 11, and results of the chemical analyses of the 

samples are given in table 2.

Core drilling. Core drilling and chemical analyses to determine 

the subsurface continuity, extent, and composition of deposit 1 were 

undertaken by the U. S. Bureau of Mines in 1948-50. Eleven holes, 

totaling 3,048 feet, were drilled. The location of the holes is shown 

on plate 11. The diamond-drill cores were analyzed in great detail 

by the Bureau of Mines and the results have been reported by 

Rutledge and others (1953).

Chemical composition. The magnesia content of deposit 1 is erratic and undesirably high in many of the surface samples (table 2). 

Analyses of the Bureau of Mines drill cores also show the magnesia 

to range from 0.3 to 17.15 percent. Some stratigraphic zoning of 

the magnesia is suggested by the distribution of the compound in 

the rocks penetrated by drilling, but a comparison of the core analyses with those of the surface samples shows little correlation when 

the suggested zoning at the drill-hole level is projected to the surface. In the area tested by drilling, more than half the limestone 

has an average magnesia content exceeding the arbitrary 3 percent 

limit.

TABLE 2. Chemical analyses of surface samples of limestone deposit 1 

[Analyst. R. K. Bailey]

Sample

53

54

56

58

59

60

61

62

63

64

65

66

67

68

69

HC1 

insolubles

0.76

.96

1.38

.84

.84

.76

1.94

1.04

.80

4.90

4.86

2.84

2.42

1.78

1.72

R20s

0.26

.18

.25

.18

.24

.26

.24

.12

.24

.24

. 30

.30

.20

.22

.18

CaO

44.76

47.08

46.46

51.92

49.26

44.84

46.06

49.32

46.50

52.58

51.96

53.22

51.96

53.24

52.20

MgO

9.66

7.52

7.66

3.29

4.94

9.04

7.64

5.30

7.92

.68

1.02

1.05

2.33

1.58

2.42

COz 1

45.37

45.07

45.15

44.29

44.18

44.94

44.40

44.37

45.00

42.04

42.61

42.84

44.04

43.52

43.43

P2 05

0.04

.02

.03

.02

2.01

2.01

2.01

2.01

2.01

2.01

2.01

2.01

2.01

2.01

2.01

Total

100. 85

100.83

100.93

100. 54

99.47

99.85

100.29

100. 16

100. 47

100. 45

100. 76

100.26

100.96

100. 35

99.96

1 Calculated from CaO and MgO.

2 The PiOs may be less than .01 percent but was present in appreciable amounts and was designated as 

being 0.01 percent.
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 87

FIGURE 16. Limestone deposit 2 (left foreground) looking westward.

Perhaps a suitable calcareous component could be Obtained from 

deposit 1, but, other factors being equal, this limestone is generally 

inferior to deposits 2 and 3. ,

I

DEPOSIT 2

General description. Deposit 2 crops out along the summit of 

the west end of the ridge southwest of the junction of the West 

Fork with Windy Creek (fig. 16). Its western limEt is approximately 7.8 miles, measured along Windy Creek and the West Fork, 

west of the Alaska Railroad. Outcrops of the deposit are found 

mainly between altitudes of 3,300 and 3,550 feet. The lower altitude is about 1,180 feet above the railroad at the 'Windy Creek 

bridge.

In physical appearance the limestone of deposit 2 is very similar 

to that of deposit 1. It is dark gray to black on fresh surfaces and 

weathers to a light gray. The original bedding is ajlmost entirely 

obscured, but the trend of the body as a whole is al^out N. 70° E. 

and the strata dip 65°-75° SE.

The overturned beds of brightly colored pre-Devonlian calcareous 

argillites and shales lie above the limestone. Beneath) the limestone 

are dark cherty conglomerates and black shales of the Devonian 

system. Plate 11 shows a cross section of deposit 2 along a prolongation of sample line 38.
88 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

Sampling. Six samples composed of fresh chips taken at 5-foot 

intervals were collected along lines normal to the strike. Sampled 

localities are shown on plate 11.

Chemical composition. Results of the chemical analyses of the 

samples (table 3) indicate that the deposit is remarkably uniform 

in composition. Sample 30, taken across the west end of the deposit, contains 3.2 percent magnesia, which is slightly in excess of 

the arbitrary limit, but the weighted-average magnesia content of 

all the samples is only 1.3 percent. The weighted average of the 

alkali content is 0.16 percent.

If the surface sampling is representative of the deposit as a 

whole, it would appear that the deposit would be chemically acceptable as far as content of magnesia and alkalies is concerned.

Estimated available limestone,. Deposit 2 is assumed to have an 

average thickness of 300 feet over a lateral extent of 4,800 feet and 

to dip 70° S. It is estimated that about 6 million short tons of 

limestone could be removed by quarrying to a 50-foot depth.

TABLE 3. Chemical analyses of samples of limestone deposit 2

[Analysts: L. I. Shapiro, L. E. Reichen, and S. M. Berthold. Na2O, K2O, and PzOs determined by flame 

photometer; all other determinations by rapid colorimetric and titrimetric procedures]

Sample

30 

32 

34 

36 

38 

39

Volume-^ 

average

Laboratory No.

1911 C 

1912 C 

1913 C 

1914 C

weighted

SiO2

1.4 

1.5 

1.4 

2.2 

1.5 

1.1

1.5

AhO3

0.00 

.30 

.30 

2.4 

.46 

.00

0.5

Fe2O3

0.2 

.16 

.30 

.30 

.32 

.2

0.2

MgO

3.2 

1.1

-07 

1.5 

.07 

2.5

1.3

CaO

51.2 

52.8 

54.1 

51.5 

54.0 

52.0

52.8

Na2O

0.1 

.29 

.16 

.17 

.11 

.1

0.1

K2O

0.1 

.12 

.11 

.14 

.13 

.1

0.1

P2O5

0-1 

.00 

.02 

.01 

.02 

.1

0.04

SOs

0.08 

.06 

.08 

.08

0.08

Ignition 

loss

43.3 

43.3 

43.5 

42.8 

43.1 

43.4

43.2

Total

99.6 

99.7 

100.0 

101.1 

99.8 

99.5

99.8

DEPOSIT 3

General description. Deposit 3 includes part of a bed of massive 

limestone that is thicker and of greater lateral extent than any 

others in the Windy Creek area. It crops out along an eastwardtrending belt that crosses the valley of the West Fork at the junction of the principal headwater tributaries (pi. 11 and fig. 17). 

This massive limestone unit of the Devonian (?) system was first 

mapped on a reconnaissance scale and described by Capps (1932, p. 

253), who traced its outcrops from the head of Windy Creek westward along the crest and southern slopes of the Alaska Range for 

a distance of about 20 miles.

A sketch map of the deposit was made by the Geological Survey 

in 1950 (Moxham and others, 1951, fig. 10), and samples of the 

principal outcrops were collected and analyzed. The boundaries of
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 89

FIGURE 17. Headwaters of West Fork of Windy Creek looking northward. Deposit 3 is 

in the left and right middle ground in the thicker limestone beds (Dll) which are 

bounded by Devonian limestone, graywacke, and shale (Dl).

deposit 3 were mapped on a new base map (pi. 11) in 1951. The

deposit was subsequently sampled by the U. S. Bureau of Mines 

(Rutledge and others, 1953).

Deposit 3 consists of that part of the massive limestone which is 

generally accessible from the valley of the West Plork (pi. 11). 

Outcrops of deposit 3 are found from creek level (altitude 3,200 

feet) to the 5,000- to 6,000-foot summits of the steep serrate ridges 

that form the valley walls. The lowest outcrops, at cteek level, are 

about 11.2 miles (measured along Windy Creek and the West Fork) 

west of the Windy Creek crossing of the Alaska Railroad and are 

about 1,100 feet above the level of the railroad bridge.|

The more accessible part of the deposit is on the edst side of the 

West Fork. Here the bedrock of the eastern part lof the valley 

floor and of the lower slopes of the valley wall is imantled with 

talus which has accumulated in vast quantities at ttye base of the 

more precipitous slopes. Nearly continuous exposures are found on 

the steep slopes from the upper limit of the talus to the top of the 

ridge that forms the eastern valley wall of the Wes!t Fork.

The limestone in deposit 3 is very dense and fine gjrained in texture. Fresh surfaces are dark to bluish gray, weathering to a light 

gray. Locally, particularly in the central part of the deposit, the 

limestone exhibits a banded coloration due to thin alternating layers of dark bluish-gray and light-gray material. The calcareous
90 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

strata are closely folded and locally are intricately contorted, but 

in genera] the degree of shattering appears to be less than that seen 

in deposits 1 and 2. The attitudes of individual beds vary greatly, 

but the general impression is that the limestone body as a whole 

stands nearly vertical. The general trend of the deposit is easterly.

Deposit 3 has an outcrop width of about 3,000 feet at its widest 

extent in the valley of the West Fork, but a stratigraphic thickness 

of not more than half that figure if the structural interpretation is 

correct that is, that both limbs of a closely compressed fold are 

represented.

Plate 11 includes a longitudinal section through deposit 3.

Sampling. In 1950 the U. S. Geological Survey collected samples 

of the limestone along lines generally normal to the strike near 

creek level in the valley of the West Fork. The material comprised 

fresh chips collected at about 5-foot intervals. Additional samples 

were taken at higher altitudes, where accessible, on the east side of 

the valley. The sampled localities are shown on plate 11.

That part of deposit 3 east of the West Fork was sampled in 

detail by the U. S. Bureau of Mines in 1951 and the results are 

given in the report by Rutledge and others (1953).

Chemical composition. The bedrock of deposit 3 on the east side 

of the West Fork is not as uniform in chemical composition as deposit 2. The alumina and iron vary over a considerable range as 

does the ratio between these two compounds in particular samples. 

The average magnesia and alkali content is well within the required 

limits. The Bureau of Mines analyses indicate that the belt of talus 

at the foot of the east valley wall is of similar character to the bedrock throughout approximately the northern half of the talus 

deposit. South of the midway point the chemical composition tends 

to be somewhat erratic, with a generally lower lime content prevailing. Samples collected on the west side of the West Fork are generally more uniform chemically than those on the east; the alumina 

and iron content is lower as is the alumina: iron ratio.

Estimated available limestone. The estimated available limestone 

has been divided into two categories, talus and bedrock. The approximate distribution of the talus and its inferred cross-sectional 

configuration are given in plate 11. By use of these data the northern half of the talus deposit is estimated to include about 8 million 

tons of limestone. The bedrock on the east side of the West Fork 

between creek level and an arbitrarily chosen altitude of 4,000 feet 

would comprise roughly 180 million tons of limestone, based upon 

the longitudinal section shown in plate 11. Probably about 10 million short tons lie west of the West Fork above creek level.
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 91

TABLE 4. Chemical analyses of samples of limestone deposit 3

[Analysts: L. I. Shapiro, L. E. Reichen, and S. M. Berthold, NajO, KaO, and PiOi determined by flame 

photometer; all other determinations by rapid titrimetric and colorimetric procedures]

Sample

491

492

493

494

495

496

497

498

499

501

502

503

504

541

542

543

544

545

546

547

548

549

5410

5411

551

555

559

561

562

563

564

565

566

567

568

569

5610

Laboratory No.

501920 C

501921 C

1922 C

1923 C

1924 C

1925 C

1926 C

1927 C

1928 C

1929 C

1930 C

1931 C

1932 C

1933 C

1934 C

1935 C

1936 C

1937 C

1938 C

1939 C

1940 C

1941 C

1952 C

1953 C

1954 C

1942 C

1943 C

1944 C

1945 C

1946 C

1947 C

1948 C

1949 C

1950 C

1951 C

SiO2

7.1

3.5

2.1

8.6

6.2

5.4

6.0

25.5

6.6

3.2

7.9

5.2

5.9

3.9

2.7

2.2

2.2

3.0

5.9

4.3

4.2

4.0

3.8

4.9

16.2

12.5

16.4

6.5

7.7

6.1

5.5

4.2

7.3

2.4

4.3

2.6

3.4

AbOs

2.3

2.3

.80

2.5

.95

1.1

.64

5.6

1.1

.31

1.3

.80

1.0

.59

.29

.00

.21

.83

.69

1.9

1.4

1.6

.79

1.4

2.5

2.4

3.3

.4

.6

1.3

.6

.6

.4

.3

.4

.1

.5

Fe2O3

0.19

.78

.32

.80

.40

.46

.45

2.1

.41

.34

.85

.78

.64

.19

.19

.18

.30

.30

.40

.27

.19

.24

.16

.11

1.2

1.3

2.0

.4

.4

.6

.4

.3

.3

.2

.1

.1

.2

MgO

1.4

2.9

1.4

1.0

1.0

1.8

1.3

2.0

1.9

.83

2.4

8.0

2.1

2.0

.77

.76

.51

.75

1.6

1.1

1.2

1.2

1.0

.60

1.2

1.3

1.2

1.6

1.3

1.9

2.5

1.1

1.0

.6

1.3

.4

1.8

CaO

48.5

47.9

53.0

47.7

50.0

50.3

50.1

33.5

50.1

53.1

46.9

43.4

48.4

50.7

53.1

53.7

53.6

52.8

50.3

50.7

51.0

51.0

51.8

51.4

43.6

45.9

42.3

49.6

48.8

49.0

49.5

51.4

49.4

53.2

52.0

54.2

51.0

Na2O

0.22

.30

.50

.83

.38

.62

.37

1.3

.59

.21

.63

.33

.18

.23

.20

.20

.20

.24

.37

.32

.28

.26

.30

.26

1.1

.60

.82

.3

.3

.3

.3

.2

.4

.2

.2

.1

.3

KsO

0.11

.12

.13

.28

.13

.19

.19

.70

.20

.07

.16

.08

.09

.15

.11

.10

.08

.08

.11

.10

.09

.08

.11

.08

.31

.47

.62

.1

.1

.2

.1

.1

.1

.1

.1

.1

.1

P2 0S

0.03

.01

.01

.03

.02

.01

.02

.06

.00

.01

.03

.01

.02

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.01

.09

.04

.04

.1

.1

.1

.1

.1

.1

.1

.1

.1

.1

SOs

0.84

.32

.24

1.16

.41

.35

.51

.64

.61

.19

.30

.11

.16

.18

.08

.12

.08

.09

.33

.30

.12

.13

.10

.29

.68

.43

.10

.00

.2

.4

.2

.2

.3

.1

.00

.00

.2

Ignition 

loss

38.8

42.4

42.6

38.2

40.6

40.4

40.4

28.2

39.6

41.9

39.4

41.8

40.5

42.1

42.6

42.8

42.5

42.4

40.7

42.6

42.0

42.1

41.8

41.3

34.6

35.0

32.2

41.0

39.6

40.0

41.3

41.6

40.0

42.6

42.2

43.1

42.1

Total

99.5

100.5

101.1

101.1

100.1

100.6

100.0

99.6

101.1

100.2

99.9

100.5

99.0

100.0

100.0

100.1

99.7

100.5

100.4

101.6

100.5

100.6

99.9

100.4

101.5

99.9

99.0

100.0

99.1

99.9

100.5

99.8

99.3

99.8

100.7

100.8

99.7

OTHER DEPOSITS

Limestone deposits have been found in many other localities in the 

Windy Creek area but they are generally regarded as inferior to 

deposits 2 and 3, owing to some aspect of their chemical quality, 

size, or accessibility.

A deposit comparable in size to deposit 1 is intersected by the 

valley of Little Windy Creek (pi. 11). The material was sampled 

by Cobb in 194Y and by the Bureau of Mines in 1949. The Geological Survey sample locations are shown on plate 11. The analytical results, given below, indicate that about half of the limestone 

contains excessive amounts of magnesia.

Insolubles

r o

MeO--_---_

In sample

C55

3.88

. 39

52. 04

1. 66

[Analyst: R. K. Bailey]

In sample In sample

C56 C55

2. 64

. 18

50. 14

3. 98

CO2 -- ------- 42.56

P2O5 ---------- .05

Total- _-_- 100.58

In sample

C56

43. 86

. 01

100. 81
92 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

Several other deposits shown on plate 11 in the area between Little 

Windy Creek and the railroad were sampled by the Bureau of Mines 

in 1949 and some appear to be acceptable, insofar as the magnesia content is concerned, but the quantity of material is generally regarded 

as insufficient or the deposits are relatively inaccessible.

Two limestone beds averaging 40 feet in thickness crop out along 

the upper valley slopes on the north side of Windy Creek, west of 

Little Windy Creek. A chemical analysis of sample 5, which was 

taken across the thickest part of one of the beds (pi. 11), is given 

below:

[Analyst: L. I. Shapiro]

Si02 _ _____________

A12O3 _

Feg08 . _._.______._

MgO_--_-__ __.

CaO-__----_______

Na,O__ --__----_

__________ 4.3

. 1

___________ .5

___________ 15.8

_--____.-__ 34.4

. 1

K2O____--______--__-

P2O5

Total------------

. 1

________ .2

---___-. 44.4

________ 99.9

ARGILLACEOUS MATERIALS

The argillaceous component of a cement manufactured from materials available in the Windy Creek area probably would constitute 15 to 20 percent of the raw mix.

Argillaceous rocks of pre-Devonian, Devonian, and Jurassic(?) 

age at several localities were examined and samples were collected 

during the present investigation. A brief description of the various 

lithologic types is included in table 5, which summarizes the results 

of the investigation. The locations of the deposits are shown on 

plate 11 and chemical analyses of the samples are given in table 6.

PRE-DEVONIAN ROCKS

Samples 43 and 45 represent a red, green, and yellow mottled 

calcareous argillite of pre-Devonian age which crops out on the 

submmit of the ridge southwest of the mouth of the West Fork. 

The strata are south of and adjoin the limestone of deposit 2 and 

dip moderately to steeply to the southeast. They are exposed for a 

lateral distance of about 2,000 feet along the crest of the ridge. It 

is estimated that the beds are about 200 feet thick. Only a very 

thin soil mantle covers the bedrock in most of the area.

DEVONIAN SYSTEM

The abrupt lateral and stratigraphic discontinuities that characterize the rocks of Devonian age are such that most lithologic units 

are not very persistent. A few exceptions, however, were found in
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 93

the central and western part of the outcrop area of rocks of Devonian age.

Samples 6 and 17 (possibly from the same part of the section) 

were collected from a brown to black crumpled argillite that crops 

out in two gullies cut into the steep north valley slopes of Windy 

Creek (pi. 11). The strata in general dip steeply to the southeast, 

although there are many local variations. The maximum exposed 

thickness at locality 6 is about 400 feet. The lateral extent of the 

beds is concealed by soil and vegetation, but the overburden is probably not more than 2 or 3 feet thick in most places.

TABLE 5. Summary of data pertaining to argillaceous materials

Sample

C-l, C-2.- . .

302.. ..........

304.__. .....

305-- 

307.- 

308.. 

309.... .

310.- 

311-. 

318-- .

6.- 

17. 

26-- .

43,45 

48-. 

51... -

Year 

collected

1949

1949

1949

1949

1949

1949

1949

1949

1949

1950

1950

1950

1950

1950

1950

Description

stone with pyrite in small 

cubes and irregular grains.

claystone with small carbonnate veinlets and pyrite cubes.

limonite on cleavage faces.

what platy, with limonite on 

cleavage faces.

stone.

claystone.

calcareous argillite.

Attitude of beds

N. 80° E. 35° NN. 55° E. 55° SE.

N. 55° E. 55° SE.

N. 55° E. 55° SE.

N. 60° E. 85° SE.

N. 70° E. 55° SE.

N.50°E.;55°NW_

N.70°E.;67°NW.

N. 60° E. 60° SE.

N.75°E.;80°NW.

E. W.; 70° SE ..

N. 80° E. 75° SE.

N. 50° E. 70° SE.

N. 74° W.; 80° S-.

Stratigraphic 

thickness 

(feet)

10

145

50

20

50

25

60

45

70

400

100

100

200

140

400

Estimated 

material 

available 

(tons)

6,500

266,000

163,000

10,600

67,000

19,500

37,000

16,000

77,000

100,000

40,000

40,000

450,000

130,000

300,000

TABLE 6. Chemical analyses of argillaceous materials

[Analysts: A. A. Hanks, Inc.*; A. C. Vlisidis and L. I. Shapiro. NajO, KzO, and PaOs determined by 

flame photometer; all other determinations by rapid colorimetric and titrimetric procedures]

Sample

C-l... ..

C-2......

302*.. ..

304*.. ._

305*.....

307*..-__

308*. .

309*-. ___

310*-....

311*_.___

318*.. 

6.. 

17-- .

26_..____

43-.- 

45-. -

48...--

51... 

Laboratory No.

10373

10374

10375

10376

10377

10378

10379

1937 C

1939 C

1940 C

1916 C

1917 C

Si02

60.61

62.09

77.30

70.59

70.91

64.86

64.58

61.85

60.61

70.31

62.4

fi4 9

62.9

41 Q

47.6

69.3

64.4

AljOa

i K 74

16.36

9

KQ

IQ 07

13.73

16.63

16.37

IQ 1 E

14 79

17.75

1 K QA

U Q

17 0

14.7

15.6

FeaOs

7 01

7 QQ

5 41

6.43

6.09

6.71

5.07

7 99.

6.60

7.44

4.06

4

0

5.7

6.0

4 S

4.2

3.8

6.0

MgO

4 CO

5.15

2 El

2 79

2 4ft

1.76

3

QA

5

CA

4.10

2 93

1 9

i ^

1.3

2.1

2.6

QA

1.0

CaO

1 29

90

.51

.40

1 ^Q

1.66

SI

S

on

96

.41

3

0

.72

1.0

19 9

U K

.72

2 f\

NasO

97

.65

.71

.46

2.53

1.16

1.42

1.25

1.55

.28

.85

.94

84

1.7

QO

1.4

K2O

O E.Q

.75

.43

.57

.37

.61

.72

.65

.70

.68

.21

2.7

1.5

2 6

9 7

P206

.14

1.4

.13

.14

.12

.11

.15

SO3

0.55

.30

.35

.12

.10

.15

.18

.07

.67

.19

.99

.34

Ignition 

loss

2.21

4.20

4.75

4.58

5.25

5.27

6.51

4.17

4.85

7.9

5.9

6.6

16.9

14.2

5.4

4.5
94 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

Sample 48 was collected from a brown to black argillite which 

crops out for a distance of about 300 feet along the south side of 

the West Fork from creek level to an altitude of about 2,900 feet. 

The beds strike N. 55° E. and dip 20° SE. A stratigraphic thickness of about 140 feet is exposed.

JURASSIC(?) SYSTEM

The largest deposit of argillaceous material in the Windy Creek 

area is represented by the argillite of Jurassic(?) age which underlies the conglomerate of the Cant well formation at locality 51 

in the western part of the area. Here the argillite of Jurassic (?) 

age is well exposed in a northward-flowing tributary which enters 

the West Fork near the east end of Foggy Pass (pi. 11). The strata 

are primarily black argillite but include a few layers of graywacke 

and conglomerate; the beds have been cut by felsic dikes in a few 

localities; the strata strike about N. 75° W. and dip 80° S. Sample 

51 represents a stratigraphic thickness of about 400 feet of argillite. 

This general lithology persists laterally at least as far as the western limit of the mapped area. To the east the sedimentary beds 

become increasingly coarse and contain much more graywacke.

Rocks of Jurassic (?) age crop out immediately west of the Alaska 

Railroad between Windy Creek and Cantwell. The beds are composed chiefly of metamorphosed argillaceous sediments and minor 

amounts of limestone. In several localities the beds have been cut 

by dikes of granitic or dioritic composition. The strata of Jurassic (?) age dip moderately to steeply northward and strike about N. 

80° E. In 1948, Gates and Cobb sampled a shale member exposed 

in an outcrop along the west side of the Alaska Railroad (localities 

C-l and C-2, pi. 11) 1 mile southeast of Windy Creek. The sample was composed of material collected at 2-foot intervals over a 

distance of 375 feet along the railroad.

An additional sample of this material (311) was collected by 

R. E. Fellows in 1949.

Other outcrops of argillaceous rocks, rather limited in size, are 

along lower Windy and Little Windy Creeks and the Alaska Railroad. At most of these localities the deposits are mantled by a 

thick overburden of glacial outwash except where they are exposed 

by the stream erosion. The locations of samples collected by Fellows in 1949 are shown on plate 11 and briefly described in table 5.

CHERT

Modern cement-manufacturing processes require very close control of the chemical composition of the raw mix in order to produce a uniform product that will meet rigorous specifications. The
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 95

most common practice is to adjust the composition of the raw mix 

by the addition of a high-iron and (or) a high-silica component 

In appropriate quantities to attain a cement of desired chemical 

composition. Mill scale and pyrite cinder are commonly used as 

high-iron components; silica sand, quartz, and quartzite comprise 

the principal high-silica materials.

No high-iron materials are known in the Windy Creek or adjacent areas, but chert that occurs in the northeastern part of the area 

might be chemically suitable as a high-silica component. The chert 

beds, probably of Triassic age, crop out adjacent to the Alaska 

Railroad about two-thirds of a mile north of Windy station. The 

rock is black, locally weathering to a rusty hue. To the north the 

chert is overlain or intruded by greenstone.

The beds have a stratigraphic thickness of about 60 feet and are 

exposed along the strike for at least 100 feet in a southwesterly 

direction from the railroad right-of-way.

Sample 100, consisting of fresh chips collected at 5-foot intervals 

across the width of the outcrop, was taken along the railroad rightof-way. Results of the chemical analysis of the sample are given 

below:

[Analyst: Harry M. Hymen] 

SiO. - _____________________ 96. 31

A1203 - 

Fe2O3 - 

FeOMgO. 

CaO_. 

Na2O_ 

K2 O__

31

59

40

18

07

23

uo 

35

H.O + --------

H.O- ... ________

TiO__ - ---_

C02 ___ __________

P,0, -- -_ 

MnO ___ _________

Total ... _____

__________ 0.05

__________ .31

__ __ _ .06

__ _-_--_ . 04

___ _____ . 15

__ ______ .00

_ ______ 99. 79

POTENTIAL CEMENT COMPOSITION

A discussion of the potential composition of cements that might 

be manufactured from the raw materials available would involve 

many aspects of physical chemistry and economics that are not 

within the scope of this paper; furthermore, as a prerequisite to 

any serious discussion on the subject, a great deal more would have 

to be known of the chemical character of the raw materials. However, some comments are thought. warranted on the basis of the 

data that are available.

In the absence of a supplemental high-iron component, the alumina : iron ratio in the raw materials is of importance in keeping 

the tricalcium aluminate content of the finished product within the 

8 percent maximum.

The limitation of a maximum of 5 percent magnesia in cement has 

been discussed (p. 84); the relationship between the amount of this
96 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

compound in the raw materials and the cement composition is 

straightforward. The extent to which the alkali content of cement 

is harmful is a matter of controversy. In addition, because the 

alkalies will volatilize to a certain extent during burning, the alkali 

content in the raw ingredients is difficult to assess. In the computations given below no such losses are assumed, so the alkali content of the cements shown probably approaches maximum values.

It has been pointed out that the magnesia content of deposit 1 

varies widely and in many localities is excessive (p. 86). The usefulness of this deposit will depend on various economic factors and 

will not be discussed further here.

Deposit 2 is remarkably uniform in chemical composition if the 

few surface samples taken are representative of the deposit as a 

whole. The material is probably superior in this respect to any 

other in the Windy Creek area. The alumina: iron ratio of the 

weighted average of the samples is 2.5:1, but the amounts of these 

compounds are very low. The magnesia and alkalies are likewise 

low.

The massive Devonian (?) limestone, of which deposit 3 is a part, 

offers enormous reserves, but is the most remote from the Alaska 

Railroad and the present highway network. The magnesia presents 

no problem and for the most part the alkalies are within reasonable 

limits, although there may be local exceptions.

On the east side of the West Fork, the alumina and iron content 

of the limestone is somewhat varied and computations of potential 

cement composition based on the weighted average of the samples, 

with different argillaceous components, indicated a slightly excessive 

tricalcium aluminate content. Computations based on the average 

composition of the samples from the central part of the deposit 

(locality 561-560) showed the limestone was satisfactory.

Generally, the argillaceous materials are satisfactory except for 

their alkali content. Except at locality 302 the alkali content is 

somewhat high, but for reasons mentioned above (p. 84) the extent to which this is undesirable will not be discussed here.

Two potential cement compositions are given below. Mix 1 consists of 78 percent limestone from deposit 2 (weighted average of 

samples), 20 percent shale from locality 302 (table 6), and 2 percent 

Healy River coal ash. The composition of the coal ash is the average of five samples from the New Suntrana mine (Selvig and Gibson, 19-15). Mix 2 is 83 percent limestone from deposit 3 (average 

of samples 561-5610), 15 percent shale from locality 302, and 2 

percent coal ash. The computations were made in accordance with 

the method of Bogue (1947). The amounts of the synthetic compounds were computed as required by the American Society for 

Testing Materials (1950).
GEOLOGY AND CEMENT RAW MATERIALS, WINDY CREEK AREA 97

TABLE 7. Calculations of potential cement composition

Si03 _______________

A12 03 --------------

FeaOa-------------- -

CaO-_____--_--_-____

MgO --------------

Na2 O . _____-______

K2 0_. ____---__-______

P2 0«_.__ __.._ _ _

SOa------ - 

In mix 1

25. 9

4. 1

2.0

62. 4

2. 3

.3

. 3

1 9

In mix 2

24. 7

q A

1. 6

64. 1

2. 3

. 5

. 3

2. 0

Total_ __ ____---

Tricalcium silicate

Tetracalcium aluminoIn mix l

. 6

99. 8

21. 3

58.2

7. 5

6. 1

In mix 2

. 6

99. 5

42. 3

39. 0

6. 3

4.9

LITERATURE CITED

American Society for Testing Materials, 1950, 1949 Book of standards: pt. 3. 

Bogue, R. H., 1947, The chemistry of portland cement: New York, Rheinhold

Publishing Corp. 

Capps, S. R., 1932, The eastern portion of Mount McKinley National Park: U.S.

Geol. Survey Bull. 836-D. 

_____ 1940, Geology of the Alaska Railroad region: U.S. Geol. Survey

Bull. 907. 

Eldridge, G. H., 1900, A reconnaissance in the Susitna basin and adjoining

territory: U.S. Geol. Survey 20th ann. rept, pt. 7, p. 1-29. 

Moffit, F. H., 1912, Headwater regions of Gulkana and Susitna Rivers, Alaska:

U.S. Geol. Survey Bull. 498.

_____ 1915, The Broad Pass region, Alaska: U.S. Geol. Survey Bull. 608. 

_____ 1954, Geology of the eastern part of the Alaska Range and adjacent

area: U.S. Geol. Survey Bull. 989-D. 

Moxham, R. M., West, W. S., and Nelson, A. E., 1951, Cement raw materials

available to the Windy Creek area, Alaska: U.S. Geol. Survey open-file

report, 38 p., 12 figs. 

Moxham, R. M., and Eckhart, R. A., 1956, Marl deposits in the Knik Arm

area, Alaska: U.S. Geol. Survey Bull. 1039-A. 

Ross, Clyde P., 1933, Mineral deposits near the West Fork of the Chulitna

River, Alaska: U.S. Geol. Survey Bull. 849-E.

Rutledge, F. H., Thorne, R. L., Kerns, W. H., and Mulligan, J. J., 1953, Nonmetallic deposits accessible to the Alaska Railroad as possible sources of

raw materials for the construction industry: U.S. Bureau of Mines', Rept.

of Inv. 4932. 

Selvig, W. A., and Gibson, F. H., 1945, Analyses of ash from coals of the

United States: U.S. Bureau of Mines Tech. Paper 679. 

United States Weather Bureau, 1955, Climatological data, annual summary:

Washington, U.S. Government Printing Office, v. 23, no. 13. 

Wahrhaftig, Clyde, 1958, Quaternary geology of the Nenana River valley and

adjacent parts of the Alaska Range: U.S. Geol. Survey Prof. Paper 293-A. 

Waring, G. A., 1947, Nonmetalliferous deposits in the Alaska Railroad belt:

U.S. Geol. Survey Circ. 18.

INDEX

Page

67

Accessibility, area studied. -___-_.._ 73

limestone deposit 3- _....__.___. 89

Acknowledgments -----_____-_---_._. 70

Alaska Railroad belt, argillaceous materials

sampled. -_---______---_ 69

location of argillite__-_ -_____-__-_ ._ 94

location of chert beds. _--_----..._._.._ 95

location of limestone deposits _ _________ 85, 87, 89

search for cement raw materials.-- ______ 67, 68

Alaska Range, boundary of Windy Creek area. 70-71 

Cantwell formation... ____________________ 82

effect on temperature__-_-________-_______ 72

geologic mapping, ________________________ 68

intrusive activity__. ______________________ 83

limestone deposit 3 _________ ___________ 88

Pleistocene glaciation. ____________________ 82-83

Triassic limestone.. ______________________ 80

Alkali content, in cement composition_.______ 84, 96

Alumina : iron ratio, in cement composition... 95, 96 

Analyses, argillite. ___________________________ 93

chert.. _______________________ ___ ______ 95

indication of chemical character of limestone deposits... _________________ 70

limestone___________________________ 86,88,91,92

Anchorage, rail and airline connection, _ ______ 73

Anderson Pass, fault zone_ ___________________ 76

Argillite, analyses.-- __-___-_--_ 93

as cement raw material. __________________ 92-94

Cretaceous _______________________________ 82

Devonian_ ___________________ 74,75,78,79,92-94

Jurassic.- -__ _ 81,83,94

pre-Devonian _____________________ 73-74,87,92

Triassic _________________________________ 79,80

Bailey, R. K., analyses by. __________________ 86,91

Berdan, Jean M., fossils identified by.. ______ 75

Berthold, S. M., analyses by... __________._.. 88,91

Broad Pass, relation to area studied, ..._.. _ 71

Cantwell, airstrip ____________________________ 73

location of Jurassic argillite- ______________ 94

Cantwell Creek, tributary to Jack River. ____ 71

Cantwell formation, character, distribution,

and age___________ ____._____---_-- 82

relation to igneous rocks_ _________________ 83

relation to Jurassic system. _ ______________ 81

Cement composition, potential from available

materials. _______________--------_ 95-97

Chert, analyses... ____________________________ 95

cement raw material..,. _________________ 94-95

Triassic _________________________________ 80

Chulitna River area, geologic mapping. __ ___ 6£

pre-Devonian rocks----_--__-_______------ 74

West Fork, Triassic limestone and argillite. ________._______-_.._____--_-- 80

Climate..______________________ _____________

obb, E. H., fossils collected by____ _________

omposition, chemical, of limestone deposits..

Core drilling of limestone deposits. __ 

Cretaceous rocks, Cantwell formation.

Page

72

82

Devonian rocks, age__,_ ___ _ 75, 78

character and distribution________ 74-75, 78-79

structure--------.----. ___,_______----___ 76,79

limestone as cement raw material-.----.-- 85-87

Drainage_____________________________________ 70-72

Fairbanks, rail and airline connection.,-----. 73

Fault zone, limit of Devonian strata__-_-___- 76, 78

relation to Cantwell formation __________ 82

relation to Jurassic rocks ___________-_-- 81

Fieldwork_______ ________-__--_-____-__---_--- 70

Foggy Pass, drained by Cantwell Creek---___ 71

pre-Devonian rocks.-----,,.,-____--,--.- 74

Fossils, Cretaceous- ---.-.---------------- - 82

Devonian. __-_ __- -- - 75

Eocene..--------------------------------- 82

Triassic.----------- - --- -- - 80

Geography._ -- --- 70-73

Olaciation, Pleistocene...----------------- 71,82-83

Glaciers, affected by difference in precipitation.. -_-_- __-- -- 72

Greenstone, Triassic.--------------------- 80,81

Hanks, A. A., Inc., analysesby____ 93 

Hymen, Harry M., analyses by___-.- 95

Igneous rocks____ _ - -_ ------ 83

Imlay, Ralph W., fossils identified by - 80 

Introduction.----- ------- _ - ------ 67-70

Jack River, Eocene fossils.- 82

previous investigations ------------ 68

relation to Windy Creek area. 71

Jurassic rocks.__-_--- ____ - ------ 81

Limestone, analyses.------ ------- 86,88,91,92

Devonian...--- 74,78,79,85-87,88-91 

estimated amount available -------------- 88,90

location of deposits of commercial size.. - _ 85,

87,88-89 

Triassic.------------------------------ 79-80

Limestone deposit, other.- 91-92

Limestone deposit I.. ------------ 85-87

Limestone deposit 2__- ___-__ ------------ 87-88

Limestone deposit 3 ------------ 88-91

Literature cited-.--------------------- ---- 9?

Location of area.__------- ----------------- 68

99
100 INDEX

Page

Magnesia content, cement composition. __. 84, 95-96 

limestone deposit 1__.-- __-_ - __. 86 

Mount McKinley National Park, location of

area studied _ - _ 68

Nenana Glacier, fault zone - -

Nenana River, drainage of area.

fault zone--- _ ____________

previous investigations

Paleocene igneous activity._- _ - _ 83 

Phyllite, Triassic ___-___-. --____ . 80

Pleistocene glaciation._.................. 71, 82-83

Precipitation.___________.__...._ 72

Pre-Devonian rocks-..._-__- ____--_ 73-74

Present investigation____._____..._ 68-70 

Previous investigations. __-.--_-_-_-. 68 

Purpose of report----____---------_---------_- 68

Quaternary rocks..-..-.-.--------...------_ 82-83

Reichen, L. E., analyses by-_._-___ _. 88,91 

Relief..----- ---------------------- 71

Sampling of limestone deposits ___ _ _

Search for cement raw materials_............. 67

Shale, Devonian.--,____................ 78, 79

Pre-Devonian___.-...--_____........... 73-74

Page

Shapiro, L. I., analyses by_ ------- 88,91,92,93

Slate, Jurassic... -__-- _ -... _ . ____ . __ 81 

Source of construction materials for Alaska. . . 67 

Standards, chemical and physical, cement

products-.-..-. - _ _ --------- 84,85

Summit , average annual temperature --------- 72

Susitna River, previous investigation?- 68

Tanana River, relation to Nenana River. _ _ __ 71

Temperature.--. _____ .__-_.-_ _____ ... 72 

Timberline, altitude -- ____________ 72 

Topography _-.._.-.-----------.-_----_----- 70-72

Travertine.... __________________ 83

Triassic rocks __ ______________. __-_-_. 79-81

U.S. Bureau of Mines, limestone deposits

sampled by_ ---------- 86,89,90,91,92

Vegetation. ___.....-----.---___-_--_----.---- 72-73 

Vlisidis, A. C., analyses by _ -_____-_----- 93

West Fork, Windy Creek, location of limestone deposits. _... _ ----------- 85,87

Windy Creek, direction of flow.. ............. 71-72

Yanert Fork, previous investigations _ 68
Investigations of 

Construction Materials 

in Alaska

GEOLOGICAL SURVEY BULLETIN 1039

This bulletin was printed as separate 

chapters A-D

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1959
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

The U. S. Geological Survey Library has cataloged this publication as follows:

U. S. Geological Survey.

Investigations of construction materials in Alaska. Washington, U. S. Govt, Print, Off., 1959.

iii, 100 p. illus., maps (part fold., part col., in pocket) diagrs., tables. 

25 cm. (Its Bulletin 1039)

The chapters were printed separately as Bulletin 1039A-1039D.

Bibliographies included.

CONTENTS. Marl deposits in the Knik Arm area, Alaska, by R. M. 

Moxham and R. A. Eckhart. Occurrence of diatomaceous earth near 

Kenai, Alaska, by G. Plafker. Haydite raw material in the Kings 

River, Sutton, and Lawing areas, Alaska, by R. A. Eckhart and G. 

Plafker. Geology and cement raw materials of the Windy Creek area. 

Alaska, by R. M. Moxham, R. A. Eckhart, and E. H. Cobb.

1. Building materials. 2. Geology, Economic Alaska. i. Moxham, Robert Morgan. 1919- n. Title. (Series)

[QE75.B9 no. 1039] G S 59-235
CONTENTS

[The letters in parentheses preceding the titles are those used to designate the papers for separate publication]

(A) Marl deposits in the Knik Arm area, Alaska, by R. M. Moxham and

R. A. Eckhart_____________________________________________ 1

(B) Occurrence of diatomaceous earth near Kenai, Alaska, by George

Plafker_______-_-___- __-_-_--_--__---_ ------- ---- 25

(C) Haydite raw material in the Kings River, Sutton, and Lawing areas,

Alaska, by R. A. Eckhart and George Plafker____________________ 33

(D) Geology and cement raw materials of the Windy Creek area, Alaska,

by R. M. Moxham, R. A. Eckhart, and E. H. Cobb_-_._______-._ 67

ni

U.S. GOVERNMENT PRINTING OFFICE : It59 O S04834