Marl Deposits in the 

Knik Arm Area 

Alaska

GEOLOGICAL SURVEY BULLETIN 1039-A

Marl Deposits in the 

Knik Arm Area 

Alaska

By R. M. MOXHAM and R. A. ECKHART

INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA 

GEOLOGICAL SURVEY BULLETIN 1039-A

A description of the marl deposits 

and the possible use of this marl 

for making Portland cement

t ' , . jotr lojnsuiiaJiHisquG am x" M»B ton 

UNITED STATES GOVERNMENT PRINTiNS.<I)£i?4«EFjhfc»s¥6HiNGTON : 1956
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

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

Washington 25, D. G. - Price 50 cents (paper cover)
CONTENTS

Page

Abstract. _________________________________________________________ 1

Introduction._____________________________________________________ 1

Previous investigations.__-____-__-__--____-______--____________ 2

Present investigations._-___-_--_-___---___-_-__-__-____________ 2

Acknowledgments. ____________________________________________ 4

Geography. _______________________________________________________ 4

General geology___________________________________________________ 5

Sedimentary rocks.___---__-______-___-----____-_-_-__-________ 5

Pre-Cambrian__ _ __________________________________________ 5

Cretaceous. _________________________________________________ 5

Eocene. __________________________________________________ 5

Pleistocene and Recent_____________________________________ 5

Igneous rocks_________________________________________________ 12

Economic geology_________________________________________________ 12

Marl deposits.________________________________________________ 12

Wasilla Lake __--------__--_---_------------_---__-__ 12

Finger Lake.__---_---_--_--------------_--_-----_-_-____ 16

Lucile Lake. ____-_-------_-_-_---_---------------__---___ 17

Bia; Lake-.------------...------------.----------------_ 17

Otter Lake. ---------- ._____-___--_______-__________.. 18

Marl reserves.________________________________________________ 18

Chemical composition of the marl. ______________________________ 19

Coal______-_--____________________--___--__--------__-_-__--- 19

Potential cement composition. __________________________________ 20

Literature cited__________________-__--_-_--__--_-___-_----__---___ 22

Index __---_________________-__________-_-_----_----------__---__- 23

ILLUSTBATIONS

Pag« 

PLATE 1. Geologic map of the Knik Arm area.____________________ In pocket

jj 2. Aerial view of Wasilla Lake from the south showing the muskegcovered embayment underlain by marl at the Edlund deposit. Facing 12 

FIGURE 1. Index map of south-central Alaska _-_-_____-__--____--_-_ 3

2. Columnar sections of marl deposits in the Knik Arm area _ _ _ _ 8

3. The inferred distribution of marl at Wasilla Lake. __---______ 13

4. Isopachous map of the Edlund marl deposit________________ 15

5. The inferred distribution of marl at Finger Lake ____________ 16

6. The inferred distribution of marl at Lucile Lake_____________ 17

7. The inferred distribution of marl at Big Lake_ ______________ 18

TABLES

Page 

TABLE 1. Chemical analyses of water from lakes in the Knik Arm area__ 11

2. Chemical analyses of auger-hole samples of marl_____________ 14

3. Calculations of potential cement compositions.______________ 21

4. Chemical requirements for type II portland cement..__________ 21

in

INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

MARL DEPOSITS IN THE KNIK ARM AREA, ALASKA

By E. M. MOXHAM and E. A. ECKHART

ABSTRACT

Marl occurs in and adjacent to at least five lakes in the Knik Arm area in 

south-central Alaska. The most significant deposits are near Wasilla, about 30 

miles north of the city of Anchorage.

Accumulation of the calcareous material has taken place in sheltered embayments and shallow marginal areas of the lakes; algae probably act as the precipitating agents. In some places the embayments have been completely filled with, 

marl and subsequently covered by a layer of muskeg, effectively sealing off the 

deposits from the lakes proper.

The marl is probably chemically suitable for the manufacture of Portland 

cement, but the inferred reserves about one million tons (dry weight) would 

be insufficient for modern large-scale operations.

The deposits described represent only the more obvious occurrences of marl, 

found during a brief reconnaissance of a small part of the Knik Arm area. If 

further investigation should become warranted, particular attention should be 

directed toward finding buried shoreline deposits that are usually higher in 

CaCO3 than the other lacustrine materials found in the area.

INTRODUCTION

The occurrence of marl at several localities in the Knik Arm area of 

south-central Alaska (fig. 1) lias been known for many years. In 

1916 Daniel M. Lynch discovered a deposit of the lime-rich material on 

the margin of Otter Lake (pi. 1), on what is now the Fort Richardson 

Military Reservation adjacent to the city of Anchorage. A few tons 

of the marl was calcined to produce lime for agricultural purposes 

(Martin and others, 1919, p. 27). About this same time, or possibly a 

few years before, a Mr. Stearns found marl on his land on the south 

shore of Wasilla Lake about 30 miles north of Anchorage. This 

deposit is now called the Edlund deposit. Other deposits of marl 

near the east shore of Big Lake, about 40 miles north of Anchorage, 

were reportedly used locally for agricultural purposes for many years.
2 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA 

PBEVIOUS INVESTIGATIONS

Capps (1940) made a reconnaissance survey of the geology of the 

Knik Arm area. Dobrovolny and Miller* mapped the geology of the 

Anchorage area, with major emphasis on the unconsolidated deposits 

of the Knik Arm lowlands. In the period 1949-51, Trainer (1953) 

made a detailed study of the northern part of the region in connection 

with an investigation of the geology and ground-water resources of 

the Matanuska Valley agricultural area.

In 1950 the Territorial Department of Mines surveyed the Edlund 

deposit and made chemical analyses of auger-hole samples that had 

been collected by William Edlund.

The only previous investigation of the marl deposits by the Geological Survey was a brief examination of the Otter Lake deposit by 

Martin (Martin and others, 1919, p. 27).

A detailed examination of the marl deposit on the south shore of 

Wasilla Lake was made by Dachnowski-Stokes (1941) in connection 

with an investigation of the peat resources of Alaska.

PBESENT INVESTIGATION

This study of the marl deposits in the Knik Arm area was undertaken in conjunction with the Geological Survey's investigation of 

industrial minerals in Alaska. The principal purpose of the work was 

to determine the potential value of the known deposits of marl as a 

portland cement component and to determine whether additional 

deposits existed in the region.

The meager information available at the outset of the investigation 

indicated that the area between Palmer and Big Lake, in which two of 

the three known marl deposits had been found, held the most promise 

of additional deposits. The major part of the fieldwork, therefore, 

was done in that area.

A preliminary examination of the Edlund deposit indicated that the 

marl occurred in a muskeg-covered former embayment of Wasilla 

Lake. The present lake bottom immediately adjacent to the filled-in 

area appeared to be covered with marl or calcareous mud and was 

thought to represent the lakeward growth of the Edlund deposit. It 

seemed likely, therefore, that the presence of calcareous deposits on 

present lake bottoms, in addition to being of possible economic significance in themselves, might indicate additional lake-margin deposits, 

now buried and concealed by muskeg.

Most of the lakes in the Knik Arm area are relatively shallow, and 

the water is clear. As the marl and associated calcareous mud are

1 Dobrovolny, Ernest, and Miller, R. D., 1950, Descriptive geology of Anchorage and 

vicinity, Alaska : U. S. Geol. Survey Open File Report.
MAEL DEPOSITS IN THE ENIK ARM AREA

FIGURE 1. Index map of south-central Alaska.
4 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

generally light in color, an aerial reconnaissance was considered to be 

the quickest means for determining at least the general distribution of 

the more extensive areas of lake-bottom calcareous deposits. An 

aerial reconnaissance was made over the northern part of the region 

(north of the north shore of Knik Arm) between Palmer and Big Lake. 

From the air, the color of the calcareous bottom deposits ranges from 

greenish white in shallow (2 to 4 feet) water to light green and gray in 

deep water, and it was noted that the most extensive deposits of lightcolored material occur in four lakes Wasilla, Finger, Lucile, and 

Big Lakes.

Subsequent to the aerial reconnaissance, the lake-bottom deposits 

were tested from a boat by means of a 6-inch diameter Iwan auger or a 

2-inch diameter spiral auger. Three- to six-foot lengths of 6-inch 

diameter stove pipe were driven into the bottom deposits to case the 

upper few feet of the hole, preventing caving. Auger holes also were 

drilled in the Edlund deposit adjacent to Wasilla Lake, and in other 

shoreline areas of Lucile, Finger, and Big Lakes, at localities thought 

to be former embayments of those bodies of water.

The present investigations were made during July 1951 by the 

writers assisted by E. A. Wilkens and Winton Bakke.

ACKNOWLEDGMENTS

The authors acknowledge the help and cooperation of D. L. Irwin, 

Director of the Alaska Agricultural Experiment Station and William 

Edlund, who generously gave his time and assistance to the authors 

and made available the map of the deposit and the results of his test 

drilling.

GEOGRAPHY

The geographic limits of the Knik Arm area have been arbitrarily 

chosen and are indicated by boundaries on plate 1. The region includes the city of Anchorage and the Matanuska Valley agricultural 

area, two of Alaska's most heavily populated and economically important areas. Several major airlines, the Alaska Railroad, and a network of all-weather highways provide easy access the year around.

The major portion of the region is occupied by the lowlands adjacent to Knik Arm, a northward extension of Cook Inlet, and the 

swampy flats of the lower Susitna and Matanuska River drainage 

systems.

Southeast from Knik Arm, the steep, heavily forested slopes of the 

Chugach Mountains rise abruptly from the lowlands to altitudes 

from 6,000 to 7,000 feet. The southernmost ridges of the Talkeetna 

Mountains border the lowlands in the extreme north-central and 

northeastern portion of the region.
MARL DEPOSITS IN THE KNIK ARM AREA 5

The climate of the Knik Arm area, in comparison to the interior 

of Alaska, is relatively mild; the temperature during the summer 

months averages about 55° F. and the winter average is about 15° F. 

Snow can be expected by late October and sometimes occurs as late 

as May. The average total precipitation is about 18 inches (U. S. 

Weather Bureau, 1950).

GENERAL GEOLOGY

The rocks in the Knik Arm area range in age from Pre-Cambrian 

to Quaternary (pi. 1). Bedrock is exposed chiefly in the mountainous areas that border the Knik Arm lowlands on the east and north, 

and in the valley of the Matanuska Eiver.

SEDIMENTARY ROCKS

The pre-Quateriiary rocks that border the Knik Arm lowlands 

range in age from Pre-Cambrian to Eocene. Brief descriptions of 

the major units are given below.

PRE-C AM BRIAN

The Birch Creek schist crops out on the south flank of the Talkeetna 

Mountains. The unit comprises mica, quartz, and chlorite schists and 

phyllite, generally dark colored, weathering locally to a rusty hue. 

The rocks are massive where fresh and assume a platy or fissile structure where weathered.

CRETACEOUS

A thick series of dark-colored slate, graywacke, and argillite form 

the core of the Chugach Mountains bordering the Knik Arm area on 

the east. The rocks are typically fine grained and occur in alternating bands of the several lithologic types.

The Matanuska formation shale, graywacke, and sandstone occupies the lower slopes of the Matanuska Valley. Shale dominates the 

lower part of the formation, with sandstone and graywacke predominating in the upper part.

EOCENE

Eocene rocks, comprising mainly shale, sandstone, arkose, conglomerate, and coal, crop out on the south flank of the Talkeetna Mountains. 

The basal part of the Eocene section is chiefly conglomerate and 

arkose with fine-grained clastic sediments and coal in the upper part.

PLEISTOCENE AND RECENT

The lowlands that constitute the major part of the Knik Arm area 

are mantled by thick unconsolidated sediments of glacial and glaciofluvial origin, as well as terrace, beach, estuarine, lacustrine, and

364221 56 2
6 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

alluvial deposits. In the northern part of the area the Pleistocene 

deposits are nearly everywhere overlain by 1 to 3 feet of Kecent gray 

loess.

During postglacial development in the lowland areas, physical, 

chemical, and organic conditions in certain of the lakes became conducive to the precipitation of CaCO3 , particularly in sheltered embayments and shallow, nearshore areas. At some localities the lakepond-muskeg sequence has progressed to such an extent that the 

embayments are now completely filled with lime-rich deposits and 

are overlain by muskeg, that effectively seals these areas from the 

lakes proper. The calcareous deposits comprise two major stratigraphic units in most localities (fig. 2); the lower unit, deposited on a 

sand or gravel bottom, is relatively high in CaCO3 and ranges in 

color from wKite through light gray to light tan. In general, the 

lighter color reflects a relatively high CaCO3 content while the darker 

shades indicate a decrease in CaCO3 and an increase in organic and 

terrigenous material. Where present, the lower of the two calcareous 

units ranges in thickness from a few feet to 20 feet or more. The 

marl is quite soft while wet, very sticky, and usually plastic. It dries 

in coherent masses of finely granular material that may be crushed 

to a powder between the fingers.

The lower marl deposits are nearly everywhere overlain by a layer 

of light-tan to light-gray calcareous silt that ranges in thickness from 

less than 1 foot up to 8 feet. In some localities the marl is gradational into the overlying silt. Elsewhere the contact is fairly sharp. 

The silt layer apparently reflects either a change of the regional base 

level whereby a greater proportion of terrigenous and organic debris 

was deposited in relation to the chemical sediments or a change in 

the chemical or physical environment that decreased the precipitation 

of CaCO3.

The calcareous deposits, from a genetic standpoint, are hybrid in 

character in that they represent accumulations of chemical precipitates 

mixed with varying amounts of clastic sediments and organic matter. 

As the CaCOs content of the deposits sampled ranges from 12 to 77 

percent, the more impure materials would be more properly classified 

as calcareous silt rather than marl; 25 percent CaCO3 is commonly 

used as an arbitrary lower limit for marl (PettiJohn, 1949, p. 286). 

For simplicity, however, all the light-colored calcareous lacustrine 

deposits are referred to as marl in this paper.

Diatoms from marl collected by the authors at two localities in the 

Knik Arm area were identified by K. E. Lohman. Sample 3606 is 

from the southwest end of Wasilla Lake (drill hole 3, fig. 3); sample 

3607 is from the east end of Big Lake. The following forms were 

reported:
MARL DEPOSITS IN THE KNTK ARM AREA 7

S606 3607

Achnanthes flexella (Kiitzing) Brun________________ F * 

Amphora ovalis Kiitzing________________ _ F F

Caloneis bacillum (Grunow) Nitzsch_______ R 

obtusa (Wm. Smith) Cleve_____________________ F F

cf. C. silicula (Ehrenberg) Cleve________________ F

Cocconeis placentula Ehrenberg____________________ B ___

CycloteUaatttiqua Wm. Smith________ ________ B ___

operculata (Agardh) Brebisson_____________ __ B 

cf. G, temperi Brun_ _____________ R 

Cymbella aequalis Wm. Smith________ _ R

cf. C. cistula (Hemprich) Grunow_________________ F 

cuspidata Kiitzing_ ____________________ F 

cf. C. cymbiformis (Ehrenberg) Van Heurck__________ F ___

ehrenbergii Kiitzing__________________________ C F

ffracillis (Rabenhorst) Cleve__________ __ F

cf. C. Jieteropleura (Ehrenberg) Kiitzing_____________ R _

mexicana (Ehrenberg) Schmidt_________________ R _

turgida Gregory _ ______________________ _ R

ventricosa Kiitzing__________________________ F B

sp. __ _______________________ F

Epithemia intermedia Fricke_______________________ _ R

sorex Kiitzing_____________________________ _ R

turgida Gregory _ _______________«.____ F _

turgida var. granulata (Ehrenberg) Grunow__________ F __

zebra var. porcellus (Kiitzing) Grunow_____________ F R

Gomphonema bohemicum Reichelt and Fricke___________ R

constrictum Ehrenberg _________________ ___ __ B

intricatum Kiitzing___ _________________ F 

Mastogloia smitMi var. lacustris Grunow___________ _- R

sp._______________________________________ F R

Navicula cuspidata Kiitzing__________________ _i__ R ___

oblonga Kiitzing____________________________ F R

cf. N. peregrina (Ehrenberg) Kiitzing__________ C C

pupula var. capitata Hustedt__________ _ R 

pupula var. rectangularis (Gregory) Grunow_____ R

radiosa Kiitzing_____ ________ _ F F

scutelloides Wm. Smith______________________ B

tuscula (Ehrenberg) Van Heurck_________________ F F

yeidium amphirhynchus (Ehrenberg) Boyer _ _ F F

bisulcatum (Lagarstedt) Cleve_______ _____ F F

iridis (Ehrenberg) Cleve________ __ F 

sp._____________-____________ R 

Nitsschia cf. N. frustulum (Kiitzing) Grunow_____________ R 

cf. N. heufleriana Grunow _ __ _ R 

Pinnularia dactylus var. demararae Cleve _ _ B 

major (Kiitzing) Wm. Smith___________________ F R

microstauron (Ehrenberg) Cleve___ _ F 

viridis (Nitzsch) Ehrenberg_________________ F R

sp.________ F 

Rhopalodia gibba (Kiitzing) O. Muller_________________ R ___

Stauroneis- sp.___ - C C

Surirella Mnearis var. constriota (Ehrenberg) Grunow-_ _ R 

1 The letters refer to the abundance of the forms in the samples: C, common; F, 

frequent; R, rare.
Big Lake

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FIGURE 2. Columnar sections of marl deposits in the 
MAEL DEPOSITS IN THE KNIK ARM AREA 9

Lohman states 

This diatom assemblage is made up almost entirely of species and varieties 

now living in cool to cold fresh-water lakes in northern United States and Canada. 

Many of them also occur in Pleistocene deposits such as the Provo formation of 

central Utah, which contains 40 percent of the species found in the Cook Inlet 

samples. The Provo formation is dominantiy a calcareous silt containing what 

appears to be chemically precipitated lime, fresh-water molluscs and diatoms.

The deposition of marl in hard-water lakes is fairly common especially in those parts of the world blanketed by glacial drift. The 

physiographic setting of the marl deposits in the Knik Arm area is 

similar in many respects to that which has proven favorable for 

accumulation of marl in the Great Lakes region (Hale, 1903; Stout, 

1940), where the calcareous deposits have formed in lake-filled basins 

within areas mantled by glacial drift.

Several conditions must generally be fulfilled for lake marl to accumulate. The relatively high ratio of chemical sediments to terrigenous and organic debris necessitates a terrain having very low topographic relief, a precipitating agent or mechanism, and physical and 

chemical conditions such that precipation exceeds dissolution of the 

carbonates.

The precipitation of CaCO3 in fresh-water marls is commonly 

attributable to some form of organic action. Probably the most common deposits result from lime encrustations produced by Ghara 

(stonewort), a shallow-water bottom-rooted alga. Other calcareous 

deposits have been attributed to Myxophyceae (blue-green algae), 

higher aquatic plants, plankton, bacteria, and mollusks (Welch, 1935, 

pp. 176-182).

There is little evidence to indicate the agent responsible for the 

precipitation of marl in most localities of the Knik Arm area. A 

small lake near the Agricultural Experimental Farm contains many 

specimens of Chara that are heavily encrusted with CaCO3 (D. L. 

Irwin, personal communication, 1952). No examination of the lakebottom vegetation in the principal marl lakes in the Wasilla area, a 

short distance north of the Experimental Farm, was made by the 

authors, but the marl in the Edlund deposits was described as a Chara 

marl by Dachnowski-Stokes (1941, p. 56-58), who made a detailed 

examination of the muskeg and marl at that locality in 1939. He 

gives the following description 

0-42 inches; the upper 6 inches consists of light reddish-brown sphagnum 

moss peat, spongy fibrous in texture, acid and relatively free from woody material ; it grades into a mixture of brown moss and sedge peat which contains roots 

and rhizomes of the growing vegetation from the 10- to 18-inch level; the material 

rests on a thin seam of volcanic ash; below it, is reddish-brown sphagnum moss 

peat to a depth of 38 inches below the surface, which contains the matted network of roots and rhizomes from tussocky sedges; near the four-foot level is a
10 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

layer of dark brown woody sedge peat with stumps of spruce and birch on marl.

42-108 inches ; gray Ohara marl ; yellow-tinted to pink in color at lower levels ; 

at the base it merges into brown organic sediments, about 2 to 3 inches thick 

and derived from aquatic plants and plankton organism.

108-110 inches ; sandy gravel.

He has interpreted the succession of materials comprising the muskeg to indicate 

* * * the presence of an early lake and a primary free-floating aquatic vegetation which was soon replaced by species of Chara and probably certain bluegreen algae ; they are the chief agents responsible for the great precipitation of 

lime over the floor of the lake. Thereafter, trees of spruce and birch with 

their associates appeared over the surface of the marl, indicating a change to 

drier conditions. This was followed by a cool moist period associated with the 

active growth and spreading of sphagnum mosses and sedges.

A microscopic examination of one auger-hole sample of marl from 

the Edlund deposit showed a few fragments of organic remains 

(stems and oospores of charophytes) , but none of the marl fragments 

are identifiable specifically as the remains of Ohara encrustation. It 

is possible, however, that in this particular sample the original characteristic surficial configuration of the Chara may have been destroyed 

by augering.

Deposition of CaCO3 elsewhere in the world is known to have resulted from physical and chemical processes without the benefit of 

organisms. To determine whether seasonal temperature changes 

or other purely physical phenomena, or both, might be at least in 

part responsible for the marl in the Knik Arm Lakes, the CaCO3 

saturation of the water of Wasilla Lake has been calculated. Chemical analyses of water from Finger and Lucile Lakes and Cottonwood 

Creek (outlet for Wasilla Lake) are given in table 1. Sample 672 

which appeared to most nearly approach CaCO3 saturation was 

used in the calculation below.

The CaCO3 saturation pH at 15 °C has been calculated from an 

expression derived by Larson and Buswell (1942, p. 1676) 

saturation pH=log^-log [Ca++]-log [alky]+9.3+ ^^ 

K2 1+5.3VAI+5.5AI

where

Ks=the solubility product for CaCO3 =6.11 X 10~» (at 15°C) 

K2 =the second ionization product for H2CO3 =3.72 X 10-" (at 15°C) 

A«=2.5 X lO-5 X total dissolved solids =.0035

and [Ca4*] and [alky] are in ppm (as Ca and CaCO3, respectively). 

Substituting the values given above and from water analysis sample 

672, table 1,

saturation PH=log 8^* 1 * 1n°7-» 1 -log 8 37-log K 112+9.3+ 2V035

.3V.0035 + 5.5C0035) 

=8.0
TABLE 1. Chemical analyses, in parts per million, of water 

[Analyst: G. W. Whetstone]

Location

Cottonwood Creek (Wasilla Lake

outlet) :

Do 

Do .. 

Do... .. -.

Do,... -...-__.- .......

Finger Lake:

Lucile Lake:

Lab. no.

SLO 2057

64

672

691

794

7QK

797

7Q7

Collection 

date

May 19,1949

Mar. 21, 1951

May 24,1951

Aug. 1, 1951

, .do .

.....do. ..

Total

hardness as

CaCOs

86.0

72.0

100.0

111.0

100.0

81.0

73.0

53.0

55.0

Noncarbonate 

hardness

0

0

0

0

13.0

0

0

0

2 n

pH

7.7

7.5

8.0

8.0

8.3

SiQ2

9.2

9.0

12.0

7.9

2.5

4.5

8.6

8.6
12 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

Thus, the calculated saturation pH is the same as the measured pH, 

which would indicate that the lake water is probably saturated with 

respect to CaCO3 . Solubility of CaCO3 is dependent upon temperature, ionic strength, pH, and particularly upon total CO2 in solution. 

There are few data available on the range of variation of these 

factors, but as the water is at or near CaCO3 saturation, the possibility 

of precipitation owing to a change in one or a combination of these 

factors cannot be disregarded.

IGNEOUS BOCKS

Granitic intrusive rocks of Cretaceous age, mostly light-gray medium- to coarse-grained granite, have intruded Cretaceous volcanic 

rocks and the Matanuska formation in the Chugach Mountains.

Volcanic rocks of Mesozoic age, chiefly tuffaceous and extrusive 

greenstone, occupy a synclinal basin along the western flank of the 

Chugach Mountains.

Volcanic rocks of Tertiary age, principally mafic extrusive rocks 

whose exact stratigraphic relations are not known, crop out on the 

south flanks of the Talkeetna Mountains.

ECONOMIC GEOLOGY

The desirability of local sources of cement for the Alaskan construction industry has long been recognized, but adequate deposits of chemically suitable raw materials are not plentiful in areas accessible to 

transportation. Other economic problems relating to the development of the known deposits have also been major obstacles.2

The marl deposits in the vicinity of Wasilla, in the northern part 

of the Knik Arm area, are far better situated geographically than any 

other known deposit of high-lime material in central Alaska. The 

Wasilla area has year-round access to the two largest potential markets, Anchorage and Fairbanks, by the Alaska Kailroad and also by 

highway. Coal is available from mines at Houston, 13 miles northwest of Wasilla, and at Jonesville, 20 miles northeast of Wasilla. The 

mines at both localities have rail connections with Wasilla. Power 

costs are relatively low in comparison with costs in other parts of 

the Territory.

MAEL DEPOSITS 

WASILLA LAKE

The inferred distributon of marl in and adjacent to Wasilla Lake 

is shown in figure 3.

The Edlund deposit is on ground that is relatively level and poorly 

drained. A 3- to 4-foot layer of water-logged muskeg, which overlies

2 Moxham, R. M., and others, 1953, Geology and cement raw materials of the Windy 

Creek area, Alaska: U. S. GeoL Survey Open File Report.
GEOLOGICAL SUKVEY BULLETIN 1039 PLATE 2

AERIAL VIEW OF WASILLA LAKE 

View from the south showing the muskeg-covered embayrnent underlain by marl at the Edlund deposit.

,MARL DEPOSITS IN THE KNTE ARM AREA

Base from Corps of Engineers 

Matanuska quadrangle, 1950

Geology by R. M. Moxham and R. A. Eckhart, 1951

Vertical scale is 10 times horizontal scale

FIGURE 3. The inferred distribution of marl at Wasilla Lake.

the marl, supports a sparse growth of scrubby spruce and brush, in 

sharp contrast to the moderately to heavily timbered area immediately adjacent. (See plate 2.)

Many auger holes have been drilled by Mr. Edlund to determine 

the thickness and extent of the deposit. The Territorial Department 

of Mines surveyed the property and determined the locations of the 

various test holes. A map of the deposit (fig. 4) was made available. 

One auger hole (1-GS) was put down by the authors near the center 

of the deposit. Chemical analyses from core recoveries at the 10-, 15-, 

and 20-foot levels in this hole are given in table 2.

The marl is fine grained and is mostly light gray to cream colored 

when wet and white when dried. Layers tinged with traces of red 

and green, and two thin bands of dark-gray silt were found, but in 

general the material appears to be uniform in composition.
14 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

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MARL DEPOSITS IN THE KNIK ARM AREA 15

Base from survey maps of the Territorial 

Department of Mines and J. C. Baldwin, 1950

Geology by R. M. Moxham, 1951

FIGUEB 4. Isopachous map of the Edlund marl deposit.

The Edlund deposit is roughly oval in outline and apparently occupies a basihlike depression; the upper surface is relatively level. 

The deposit is thickest (about 2.1 feet) near the center and thins 

rapidly toward the periphery. The isopachs shown on figure 4 

indicate the general configuration of the deposit.

In Wasilla Lake, immediately adjacent to the Edlund deposit, calcareous silt is being deposited on the lake bottom. It is probable that 

this accumulation represents the lakeward growth of the muskeg-covered marl deposit described above, although the material being deposited in the present physiographic cycle contains a greater percent of 

terrigenous debris than the underlying marl. (See cross section of the 

marl at Wasilla Lake, fig. 3.) A layer of marl was also found a quarter of a mile west of the Cotton wood Creek outlet. The marl in both 

areas is white to very light gray, plastic, and very sticky. It contains 

abundant mollusk fragments and a relatively small amount of wellpreserved plant remains. The semiconsplidated marl is overlain by 1 

to 3 feet of light-gray to light-tan mud and 3 to 4 feet of water. The 

lakeward margin of the marl deposit is generally quite abrupt, with 

the marl surface sloping steeply lakeward to a sand or gravel bottom.

Three auger holes were sunk in the Wasilla Lake deposits. Columnar sections of the material are shown in figure 2. Results of chemical 

analyses of the marl in holes 2 and 3 are given in table 2.
16 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

FINGER LAKE

Marl was found in several embayments in Finger Lake, and in two 

muskeg-covered areas near the southern and eastern shores of the lake. 

(See fig. 5.) Ten auger holes were drilled in deposits on the present 

lake bottom and three in the adjacent shoreline deposits. The marl is 

generally light tan when wet, but is white in local streaks. It is buff 

to grayish white when dry. The present lake-bottom deposits are 

overlain by 2 to 8 feet of light-tan mud and by 3 to 4 feet of water; 

the adjacent shoreline deposits are overlain by a thin layer of brown 

mud capped by 3 to 5 feet of peat.

ase from Corps of Engineers Matanuska quadrangle, 1950 Geology by R. M. Moxham and R. A. Ecfchait, 1951 

4000 Feet

FIGORE 5. The inferred distribution of marl at Finger Lake.

Table 2 gives the results of chemical analysis of marl in hole 3 in an 

embayment on the north side of the lake. Insofar as its megascopic 

characteristics are concerned, the material from hole 3 appears to be 

representative of the marl found in the Finger Lake area.

Columnar sections of the Finger Lake deposits as indicated by the 

drill cores are shown in figure 2. The marl is at least 18 feet thick 

at one locality (hole 4) at the east end of the lake; the hole did not 

reach the bottom of the marl. On the east margin of the lake about 

200 feet east of the shoreline, holes 11 and 12 show that the marl is at 

least 21 feet and 8 feet thick, respectively, at these localities. Another 

muskeg-covered embayment on the south shore of the lake (hole 13) 

contains 16 feet of marl.
MARL DEPOSITS IN THE KNIK ARM AREA

T.ATTia

17

Marl deposits were found in the west and east ends of Lucile Lake. 

(See fig. 6.) The material is white to light gray, plastic to sticky in 

consistency, and overlain by 1 to 6 feet of light-tan to brown mud. 

Test holes were drilled west and south of the lake shore, but no buried 

marl was discovered; several test holes were abandoned on striking 

permafrost. Columnar sections of the material in the lake are shown 

in figure 2. Chemical analyses of the marl in hole 1 are given in 

table 2.

Base from Corps of Engineers, Houston 

and Matanuska quadrangles, 1950

Geology by R. M. Moxham and R. A. Eckhart, 1951 

4000 Feet

FIGURE 6. The inferred distribution of marl at Lucile Lake.

The marl deposits in Lucile Lake seem to be generally thinner and 

less persistent laterally than those in the other two lakes described. 

The maximum thickness of marl found at the east end of the lake was 

about 10 feet. In the northwest part of the lake bottom, the marl is 

7 feet thick (hole 1), and an embayment in the south shore contains 

white marl at least 9 feet thick (hole 6); the bottom of this deposit was 

not reached.

BIG T.ATTR

Fourteen auger holes were drilled in the bottom deposits and along 

the margin of Big Lake. The auger-hole locations are shown in 

figure 7. Marl was found only in holes 1 and 2. Hole 1 was drilled
18 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

through about 6y2 feet of light-gray marl, overlain by 3i/£ feet of tan 

mud and 2 feet of water; hole 2 found lO1/^ feet of white to creamcolored marl overlain by 4 feet of brown mud and 1^£ feet of water. 

The bottom deposits from the other holes consisted primarily of darkbrown to tan mud and minor amounts of tan clay.

OTTER LAKE

The marl deposit at Otter Lake, SW% sec. 24, T. 14 N., R. 3. W., was 

not examined by the authors. The land is now within the boundaries 

of the Fort Richardson Military Reservation. The following description is from the field notes of Martin (1919), who visited the site in 

1917:

Muck ________________________________________ 3 feet 

Marl_________________________________________ lOfeet 

Sand and gravel

Top of marl about lake level. Occurs on beach 3 feet above lake, and 100 to 

200 feet wide. Ground then goes up in steep banks.

MAKL RESERVES

It is estimated that the marl deposits described above, in and adjacent to Wasilla Lake, contain on the order of 195,000 tons (dry 

weight), assuming the average thickness of the lake bottom deposits 

(fig. 3) is at least 10 feet. It is further assumed that the dry weight 

of the material is 54 pounds per cubic foot and the moisture content of 

the marl in place is about 50 percent.

Area underlain by marl

Auger hole

(Numbers refer to localitic* 

mentioned in text)

FIGURE 7. The inferred distribution of marl at Big Lake.
MARL DEPOSITS IN THE KNIK ARM AREA 19

At Finger Lake it is estimated that the marl may aggregate on the 

order of 500,000 tons (dry weight) assuming that the average thickness of the deposits is 10 feet (fig. 5). The thickness and distribution 

of the buried marl in the shoreline area of Finger Lake were not 

determined owing to an insufficient number of test holes.

Tonnage figures relating to Lucile Lake based on present data indicate only order of magnitude. A total of 700,000 tons might be represented by the two principal areas of deposition shown in figure 6, on 

the assumption that the marl averages 5 feet in thickness.

It is not possible to estimate the marl reserves in Otter and Big 

Lakes owing to insufficient drilling.

The inferred reserves given above include only the principal deposits 

in the Wasilla portion of the Knik Arm area and are based upon a brief 

reconnaissance, entailing relatively few drill holes. The Big Lake 

deposits and those known to exist along the shores of Finger Lake are 

not included. Additional small lake-bottom deposits of marl are 

known to occur at other localities in the area, and it seems reasonable 

to consider the brief exploratory work to date as inadequate, insofar 

as the buried shoreline deposits are concerned. The amount of marl 

reserves is relatively small for the manufacture of cement by present 

standards. It should be pointed out, however, that Alaska's unique 

economic position may greatly alter the criteria normally applicable 

in evaluating raw materials such as are involved in this problem.

CHEMICAL COMPOSITION OF THE MARL

The chemical requirements for portland cement recommended by 

the American Society for Testing Materials (table 3) are generally 

accepted by the industry. These requirements serve to govern to a 

large degree the chemical restrictions applicable to the raw materials.

The natural composition of most of the marl (see table 2) in .the 

Eiiik Arm deposits is deficient in at least two respects: an excess of 

silica (minute quartz grains, glass shards of volcanic origin, and a 

minor amount of clay minerals) and organic matter is present at most 

localities, and there is a deficiency of CaO. This is particularly true 

of the upper part of the lake-bottom deposits, which is quite high 

in silica and organic material.

The magnesia content of the marl is well within acceptable limits, 

and the alkalies do not appear to be excessive.

COAL

Coal for a cement operation is available from mines a,t two localities 

in the Matanuska Valley field Houston and Jonesville (fig. 1). The 

average analyses of mine samples from Houston (1) and Jonesville
20 INVESTIGATIONS OF CONSTRUCTION MATERIALS IN ALASKA

(2), as delivered to the Alaska Eailroad, are given below (Cooper and 

others, 1946, p. 60).

Sample no.

1.... _ ............ . . .

2 -.... _ ... . .

Proximate (percent)

Moisture

17.0 

36.7

Volatile 

matter

37.6

Fixed 

carbon

31.0

41.0

Ash

14.5 

14.9

Ultimate 

(percent)

Sulfur

0.2 

.3

Calorific 

value 

(Btu)

f 1 8, 670 

\ » 10, 440 

a 11, 000

SiO2

Percent

Na20_______________ 0.6 

K2O__________________- . 8 

SO3_______________ 3.3 

 ___ 1.4

1 Sample as received.

2 Dried at 105° C.

The Jonesyille coal is ranked as high-volatile B bituminous, having 

a moist calorific value of about 13,500 Btu. No data are available on 

the moist calorific value of the Houston coal.

Analyses of ash are available for only three coal samples from the 

Matanuska Valley field; the mine(s) from which the coal originated 

is not identified (Selvig and Gibson, 1945, p. 10). The average of the 

three analyses is given below.

Percent 

.__________________.____ 50.1

._________________ 27. 9

_________________ 8.7 

CaO__________________ 5. 9 

MgO_________________ 1. 8

POTENTIAL CEMENT COMPOSITION

It is generally accepted that the total lime-silicate content of a 

Portland cement should be between 70 and 80 percent. In order for 

these compounds to form in the desired quantities it is necessary that 

the ratio of lime to the acid oxide components of the raw mix (including the coal ash) be between 1.9 and 2.2. The average marl analyses 

given above and available analyses of Matanuska Valley coal ash 

(Cooper, 1946, p. 60) show that none of the individual lake deposits 

would meet this requirement, assuming that the raw mix would consist of 98 percent marl and 2 percent coal ash. The average limesilicate ratios of the various lake deposits are too low. The Edlund 

deposit on the other hand has an excessively high lime-silicate ratio. 

By mixing the low and high ration materials in appropriate proportions, a suitable raw mix might be obtained.

The chemical composition of the marl and coal ash may be used to 

calculate the approximate composition of a cement made from these 

materials. The phase composition of the cement in the system CaOMgO-AlaOa-SiOa-FeaOs under conditions of crystalline equilibrium 

can be calculated, and the percentages of the synthetic compounds 

tricalcium aluminate, dicalcium silicate, tricalcium silicate, and tetra-
MARL DEPOSITS IN THE KNIK ARM AREA 21

calcium alumino ferrite can be determined from the composition of 

the raw materials given above.

A number of methods have been devised to calculate the constitution 

of portland cement. They have been described in detail by Bogue 

(1947, p. 47-50) and Witt (1947, p. 39-57) and will not be dealt with 

here. T^e method devised by Bogue has been used to compute two 

potential beinent compositions shown in table 3.

Mix 1 utilizes a raw mix consisting of 70 percent Edlund deposit 

marl, 28 percent Lucile Lake marl, and 2 percent coal ash. Mix 2 

utilizes 77 percent Edlund deposit marl, 21 percent Finger Lake marl, 

and 2 percent coal ash. The marl compositions used in each computation are the averages of the auger-hole recoveries (listed in table 2) ; 

the coal-ash composition is the average of the three analyses available. 

Since the source(s) of the coal is unknown except that it is from the 

Matanuska Valley, the analyses used in the computations may vary 

widely from that actually available.

TABLE 3. Calculations of potential cement compositions

mi^i.. ..................

AltOi-.-... ..--.. -...,..

CaO. .........................

MgO _______ ______

SOj... _ __ ................

Mixl 

(Percent)

24.7

3.6

2

O

62.8

1.2

1.0

1.6

Mix 2 

(Percent)

OK n

2.2

I

n

1.0

1.3

1.5

Tetracalcium aluminate _ 

Tetracalcium alumino ferrite 

Mixl 

(Percent)

' 0.6

2.9

100.7

35.8

43.9

5.7 

6.7

Mix 2 

(Percent)

Otfr3.1

99. »

45.2

38.2

3.1 

4.fr

The potential cement compositions given above appear to be within

the limits specified in table 4. " i** i> * ! 

It 'should be emphasized, however, that the computations given

above are based upon relatively few chemical analyses. The necessary 

assumption that these samples are representative of the deposits from 

which they were collected may not be valid. Additional drill holes 

and sample analyses would be necessary to determine the lateral and 

vertical chemical variation of the marl.

TABLE 4. Chemical requirements for type II portland cement

[Specifications are those of the American Society for Testing Materials. Federal specifications are identical except that when the purchaser specifies "low-alkali cement," the 

alkali content (Na2O +0,658 percent of the K2O) shall not exceed 0.6 percent. Percent 

column : All values are maximum amounts with the exception of SiO2 , which is minimum 

amount]

Constituent 

SiO2 ' 

A12O3 _ _____

MgO _ ___ __ 

SO3 _ _..

Percent 

_ 21. 0

6.0

- _ _ 6.0

5 A

_ 2.0

Constituent

Insoluble _ _

Tricalcium silicate

Dicalcium silicate

Tricalcium aluminate

Percent 

__ _ 3.0

.5

_ 50.0

__ s.o
22 INVESTIGATIONS OP CONSTRUCTION MATERIALS IN ALASKA

LITERATURE CITED

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

Publishing Corp.

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

Bull. 907.

Cooper, H. M., and others, 1946, Analyses of Alaska coals: U. S. Bur. Mines Tech. 

Paper 682.

Dachnowski-Stokes, A. P., 1941, Peat resources of Alaska : U. S. Dept. of Agriculture Tech. Bull. 769.

Hale, D. J., 1903, Marl (Bog Lime) : Mich. Geol. Survey v. 8, pt. 3.

Larson, T. E., and Buswell, A. M., 1942, Calcium carbonate saturation inde£ and 

alkalinity interpretation: Am. Water Works Assoc. Jour. v. 34, no. 11; p. 

1667-1678.

Martin, G. C., and others, 1919, Mineral resources of Alaska, report on progress of 

investigations in 1917: U. S. Geol. Survey Bull. 692. ;:

Pettijohn, F. J., 1949, Sedimentary rocks: New York, Harper and Brothers.

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

States: U. S. Bur. Mines Tech. Paper 679.

Stout, Wilbur, 1940, Marl, tufa rock, travertine and bog ore in Ohio: Ohio GeoL 

Survey 4th series, Bull. 41

Trainer, F. W., 1953, Preliminary report on the geology and ground-water resources of the Matanuska Valley agricultural area, Alaska: U. S. Geol. Survey Circ. 268.

United States Weather Bureau, 1950, Climatological Data: Annual Summary, 

1949, v. 35, no. 13.

Welch, P. S., 1935, Limnology: New York, McGraw-Hill Book Co;

Witt, J. C., 1947, Portland cement technology: Brooklyn, N. Y., Chemical Publishing Co., Inc.
INDEX

Abstract...........

Acknowledgments - 

Analyses, coal ashmarl- -___ 

water___--._

Page

I

4

20

14

II

Big Lake, estimated marl reserves_______ 19

map ofinferred distribution of marl____ 18

marl deposits ________________... 17-18

columnar section, ________________ 8

Cement composition, calculations..--________ 21

chemical requirements_______-_._- 21

potential.___..______________ 20-21

Chemical analyses, coal ash_.

marl_________-__.

water_____..___... 

Chemical composition of marl_ 

Climate____.________.

Cretaceous rocks, igneous 

sedimentary _ .-._ _

20 

14 

11 

19

5

19-20 

12

5

Dachnowski-Stokes, A. P., quoted...- ___ 9-10 

Diatoms, identified _ _ ___ _ . ____ _ _ 7

Edlund marl deposit, chemical analyses..._..

columnar section....__.___...........

isopachous map..-.-___- ____. 

Eocene rocks..-_-__....___-----------

Finger Lake, chemical analyses, marl_ ___ 12

chemical analyses, water___ .... 

estimated marl reserves__ _ - __. 

map ofinferred distribution of marl, 

marl deposits____-..____. .. 

columnar section..._____.

Geography....____.___. _._ 4-5

Igneous rocks____..

Investigations, present.

previous__ 

Lucile Lake, chemical analyses, marl.... 

chemical analyses, water______. 

estimated marl reserves______. 

map of inferred distribution of marlmarl deposits_________.__ 

columnar section...._..__.__....

Lohman, K. E., quoted.....______..-...

Page 

14 

11 

19

17

17

Marl, chemical composition.-.._______ 19 

Marldepo its, Big Lake........_........... 17-18

chemical analyses .. ___ ____ 14 

conditions for__________..__ 9-10, 12 

Edlund deposit..-------.--------..--.--. 12-15

Finger Lake.-________________ 16 

Otter Lake-__.______________ 18 

Wasilla Lake___.___-................. 12-15,18

Martin, G. C., quoted.._______.__.. 18 

Matanuska formation.__.___-------___-_ 5, 12

Otter Lake, estimated marl reserves. 

marl deposits.._ _---------

Pre-cambrian rocks ..... .-.......

Precipitation...-____-___..._..___. 

Pleistocene rocks.._...__.______.... 

Portland cement, chemical requirements.....

Recent deposits....__.__.____...__ 6-12 

Reserves, marl...... .__.---._....- 18-19

Schist, Birch Creek ........................ 5

Sedimentary rocks__-..._..-.---.. 5-12

Tertiary rocks...-_--------.--.--------..---. 12

Volcanic rocks..-.. ------- ----_ 12

Wasilla Lake, chemical analyses, marl.. __. 14

chemical analyses, water ... _. 11

estimated marl reserves___..._.. 19

map of inferred distribution of marl....... 13

marl deposits_._____. .. .. 12-15

columnar section.....--.-.___ 8

Water, chemical analyses..-_-.-_-_----- ... 11

23

U. 5. GOVERNMENT PRINTING OFFICE: 1956