R | bureau of mines

report of investigations6002

i

SOME NONMETALLIC MINERAL

RESOURCES FOR ALASKA'S

CONSTRUCTION INDUSTRY

By R. S. Warfield

B . 1 ~E _ v I:' - . . . .* . r · ., . ..

' ' ..

7

I

UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF MINES

1962

-· I
SOME NONMETALLIC MINERAL

RESOURCES FOR ALASKA'S

CONSTRUCTION INDUSTRY

By R. S. Warfield

~ , * , + ,, report of investigations 6002

UNITED STATES DEPARTMENT OF THE INTERIOR

Stewart L. Udall, Secretary

BUREAU OF MINES

Marling J. Ankeny, Director

I
This publication has been cataloged as follows:

Warfield, Robert S

Some nonmetallic mineral resources for Alaska's construction industry. [Washington] U. S. Dept. of the Interior, Bureau of Mines [1962]

ii, 25 p. illus., maps, tables. 27 cm. (U. S. Bureau of Mines.

Report of investigations, 6002)

1. Mines and mineral resources-Alaska. 2. Construction industry-Alaska. I. Title: Nonmetallic mineral resources for Alaska's

construction industry. (Series)

TN23.U7 no. 6002 622.06173

U.S. Dept. of the Int. Library
CONTENTS

Page

Introduction and summary ........... ........................... 1

Lightweight aggregate--test results ........................ 2

Mile 67, Glenn Highway, sample 690.,.................. 2

Mile 16, Matanuska Branch, sample 678 ................ 7

Indian River argillite, samples 679 and 680.......... 7

Mineral wool--test results ............................... 11

Cement..... . .... .................. ................ .... .... . 14

Specifications .... ................................ 14

Foggy Pass limestone............................... 14

Location and accessibility ..................... 15

Physical features and climate................... 15

General geology ............. ......... .. 16

Description of deposit .......................... 16

Sampling procedures and results ................. 16

Conclusions ..................... ...........17

Shale deposits, Cantwell-Windy-Foggy Pass area ....... 17

Location and accessibility ..................... 20

General geology ............................... 20

Sampling procedures and results ................. 20
ii

ILLUSTRATIONS

Fig. Page

1. Location map of Alaska Railbelt nonmetallic deposits 3

2. Geologic map, Mile 67 shale deposit ................. 4

3. Preliminary tests of sample 690, 15-minute bloating

period in stationary kiln ........ .................. 5

4. Mile 16 shale deposit................................. 6

5. Preliminary tests of sample 678, 15-minute bloating

period in stationary kiln ......................... 7

6. Geologic map of Indian River argillite .............. 8

7. Preliminary tests of sample 679, 15-minute bloating

period in stationary kiln ......................... 9

8. Preliminary tests of sample 680, 15-minute bloating

period in stationary kiln ......................... 10

9. Geologic and sample maps, Cantwell-Windy-Foggy

Pass area ..... ....... ... .............. ... 12

10. Outcrop and talus of Foggy Pass limestone.......... 17

TABLES

1. Data from rotary kiln products ...................... 6

2. Chemical analyses of limestone and shale samples

submitted for mineral-wool blowing tests .......... 11

3. Mineral wool from Alaskan shale and limestone....... 13

4. Chemical analyses of five preliminary samples of the

Foggy Pass limestone deposit.......... .............. 16

5. Chemical analyses of Foggy Pass limestone, percent.. 18

6. Chemical analyses of shale samples, percent......... 21

7. Log of shale samples, Cantwell-Windy-Foggy Pass area 22
SOME NONMETALLIC MINERAL RESOURCES FOR ALASKA'S

CONSTRUCTION INDUSTRY'

by

R. S. Warfield 2

INTRODUCTION AND SUMMARY

Following World War II, the rapid increase in both military and civilian

activity in the area served by the Alaska Railroad stimulated interest in the

availability of local sources of nonmetallic minerals that might be used for

building materials. Except for abundant sand and gravel and some pumice, the

construction industry of the area depended entirely on high-cost imports for

building materials of mineral origin. Because continued rapid growth was

anticipated, development and use of local sources of such materials was advocated by both military and civil authorities to reduce the high costs of construction and bolster the unstable economy of the area. The U.S. Department

of the Interior began a program that included examining the numerous deposits

of nonmetallic minerals accessible to the Alaska Railroad to determine their

possible use as raw materials for the construction industry.

Preliminary field investigations were made by the Geological Survey. The

more promising deposits were subsequently examined and sampled by Bureau of

Mines engineers, and the samples were subjected to the laboratory tests necessary to indicate the chemical and physical characteristics of the raw materials or their products. Such field and laboratory investigations were conducted on clay, shale, argillite, limestone, gypsum, and pumice taken from

various parts of the area. In initial phases of the work, done from 1948

through 1952, many of the deposits examined were suitable for producing building materials. Results of the work completed during that period have been

published in a Bureau of Mines report3 giving general information and detailed

data on more than 35 deposits that were investigated.

After publication of the report, more laboratory testing was done on production of expanded shale and mineral wool} and more extensive sampling was

1 Work on manuscript completed April 1961.

Mining engineer, Alaska Office of Mineral Resources, Region I, Bureau of

Mines, Juneau, Alaska.

3 Ruthledge, F. A., Thorne, R. L., Kerns, W. H., and Mulligan) J. J,, Preliminary Report: Nonmetallic Deposits Accessible to the Alaska Railroad as

Possible Sources of Raw Materials for the Construction Industry: Bureau

of Mines Rept. of Investigations 4932, 1953, 129 pp.
2

done on limestone and shale deposits in the Cantwell vicinity. Laboratory tests

indicated that at least three of the shales previously tested would produce a

good grade of lightweight aggregate over a greater firing range than that

originally determined. Excellent mineral wool was produced experimentally in

the laboratory by mixing approximately equal portions of shale and limestone

from deposits near Cantwell. Samples from the extensive limestone deposits

in the Foggy Pass area (near Cantwell) contained a minimum of impurities that

are objectionable in cement.

This report presents detailed data on the foregoing field and laboratory

investigations that were conducted after the publication of Report of

Investigations 4932.

LIGHTWEIGHT AGGREGATE--TEST RESULTS

As a result of work completed before 1950, three deposits of shale were

determined to be worth more thorough firing tests; these were selected for

reasons of location, favorable bloating characteristics, or interest shown

by potential private users. The deposits are located at Mile 67, Glenn Highway; Mile 16, Matanuska Branch of the Alaska Railroad; and a railroad cut

along Indian River, 166 miles north of Anchorage (fig. 1).

Work included additional firing tests in a stationary kiln and rotary

kiln runs in a laboratory-size kiln to simulate commercial practice. The reason for making these later tests on relatively large samples was to define

more closely the temperature range of bloating and thus, the temperature range

within which an acceptable lightweight aggregate could be produced

commercially,

Mile 67, Glenn Highway, Sample 690

Sample 690 (about 2,300 pounds of raw material) was taken from material

exposed by the highway cut; this was the same location from which preliminary

samples 3, 4, 5, 6, and 324 were taken (fig. 2). The deposit is a nearly uniform shale with only small amounts of grit; the material crushes readily to

the desired size, producing a relatively low proportion of fines.

The later series of firing tests (fig. 3) indicated a much greater firing

range than had been determined by the earlier tests. Bloating started at

about 1,950° F., reached a peak of good bloating at about 2,100° F., and continued through 2,200° F. At the last temperature the material was becoming

overbloated, making it structurally weak.

An excellent feature of the wide bloating range was the lack of stickiness until the temperature approached 2,200° F.; thus, the full bloating range

of 250° F. could be used in commercial processing. It was demonstrated in the

laboratory-size rotary kiln that the material was easy to handle, and pelletizing or pretreatment other than crushing and sizing was not necessary.

4 Work cited in footnote 3 (p. 1), pp. 54-60.
3

FIGURE 1. - Location Map of Alaska Railbelt Nonmetallic Deposits.
4

Block shale outcrop

L.°:° Stream gravel

--- Fault, dashed where inferred

P- Strikp nnrl rdin nf hodlrlinn

&-- - -.------- 0 400 800

Scale, Feet

FIGURE 2. - Geologic Map, Mile 67 Shale Deposit.

(Geology from OSGS Preliminary Map.)
t-II

0

d

5

800 1Io00 2,000 2,100 2,200

TEMPERATURE , F

FIGURE 3. - Preliminary Tests of Sample 690, 15-Minute Bloating

Period in Stationary Kiln.
6

The bulk density

of the bloated product

varied with the temperature used and somewhat

with the size of the raw

material; the fines

bloated to a heavier

product than the coarse.

Similar density variation is also common in

commercial operations.

An excellentappearing lightweight

aggregate was produced

from the shale from the

Mile 67 deposit. The

bloated lumps had a

fine vesicular structure

with uniformly spaced

pores; also, the lumps

tended to be spherical

with a good surface

coating. In general,

the test work has indicated this shale to be

highly acceptable for

commercial production

of a lightweight

aggregate.

Table 1 and figure

3 illustrate results of

60°

o60

59° '

this test work.

FIGURE 4. - Mile 16 Shale Deposit.

TABLE 1. - Data from rotary kiln products

Temperature, Apparent Bulk density Absorption,

ample Mesh size o F. specific gravity lb./cu.ft. percent

Plus 4 1,920 1.28 79.7 11.9

Minus 4, plus 8 1,920 1.45 90.3 11.7

Plus 4 2,000 .69 43.0 10.0

Minus 4, plus 8 2,000 .97 60.4 11.8

679... Minus 2, plus 8 1,950 1.80 112.0 11.0

680.. fPlus 4 2,000 1.01 62.9 10.4

Minus 4, plus 8 1,920 1.08 67.2 10.3
0

L

a

iC!,

Id

,_

X

CD

B

I

I

7

-1

Note Weights ( lb per cu ft ) are true weights based on

specific grovity measure ments, ASTM container

weights are 10 to 15 lb per cu ft Iighter depending

on groin size B other factors

-- Less than 1/4" bloated

product size

\ - - 1/4" to 1/2" bloated

product size

, 1/2" to 3 /4" bloated

' product size

,,!.

80

60

F

[- Vk\

Mile 16, Matanuska

Branch, Sample 678

Sample 678 was taken

from shale exposed in a railroad cut at the base of the

bluff along the right bank

of the Matanuska River (this

deposit was represented by

preliminary samples 53 and

54,5 figure 4). The sample

was cut across 100 feet of

the shale deposit, located

280 feet south of Mile 16 on

the Matanuska Branch of the

Alaska Railroad.

Test work on the large

sample from this deposit

yielded results practically

identical to those obtained

from the Mile 67 deposit.

The material crushed uniformly, and the size of the

bloated product could be

controlled readily by sizing

the raw feed.

Figure 5 illustrates

results of the test work.

Indian River Argillite,

Samples 679 and 680

40

20

0 l I I-- .

0o0 00oo 2,000 2,100

TEMPERATURE, F'.

2,200

FIGURE 5. - Preliminary Tests of Sample 678, 15-Minute

Bloating Period in Stationary Kiln.

Samples 679 and 680 were

taken from argillites exposed

in the cut of the Alaska Railroad along Indian River, 4 miles south of Chulitna

Station. Sample 679 corresponds to preliminary sample 204,6 which was taken

across 40 feet of argillite, 50 feet south of the Indian River bridge at Mile

269.9. Sample 680 corresponds to preliminary sample 205 and was taken across

90 feet of interbedded argillite, 50 feet north of the same bridge (fig. 6).

From testing sample 679, it was determined that the deposit of argillite

it represented would not be suitable for production of lightweight aggregate.

The sample was a fairly soft, thin, flaky shale; the crushed raw shale tended

to be splintered and thin rather than in the desired lump form. When fired,

only a portion of the material bloated; this occurred from 1,950° F. to about

Work cited in footnote 3 (p. 1) pp. 60-61.

6Work cited in footnote 3 (p. 1), pp. 68-70.
8

12!511111 - - - m mm m

FIGURE 6. - Geologic Map of Indian River Argillite.

(Geology from USGS Map.)
It

14

ID

a.

0

6

IID

40

20

0

9

N

NN'

N

N

N

N. 1%"~

N\

Note Curves are the bloated material only.

Most of the sample did not bloat at

these temperatures.

Weights( lb. per cu. ft.) are true weights based

on specific gravity measurements. ASTM

container weights are 10 to 15 lb. per cu. ft.

lighter depending on grain size a other

factors.

I I I

1,900 2,000 200 2,200 2,300

TEMPERATURE, OF.

FIGURE 7. - Preliminary Tests of Sample 679, 15-Minute Bloating

Period in Stationary Kiln.
160

140

120

10

100

-- 0

j

C(

a 8 0

I

3? 606 0

i

\'

\

\ \\

N N

Less than 1/4" bloated

product size \

--- - 1/4" to 1/2" bloated

product size

I/2" to 3/4" bloated

proaucT size

20

-

40 -

-

Note: Weights ( lb. per cu. ft) are true weights based

on specific gravity measurements. A ST M

container weights ore 10 to 15 lb. per cu.ft.

lighter depending on grain size E other

factors.

0 - I - --

1,800 1,900 2,000

TEMPERATURE , ° F.

2100 2200

FIGURE 8. - Preliminary Tests of Sample 680, 15-Minute

Bloating Period in Stationary Kiln.
11

2,000° F. The bloat was poor at 1,950° F. and became sticky at 2,000° F. This

temperature range is considered to be too narrow for successful commercial

bloating.

Sample 680 was reported to have much the same bloating characteristics as

sample 690, except that the bloating range for sample 680 was about 50° F.

narrower. Bloating started at about 2,000° F., reached a peak of good bloating at about 2,100° F., and continued through 2,200° F. The deposit represented by this sample is considered to be a very good potential source of raw

material for lightweight-aggregate production.

Table 1 and figures 7 and 8 illustrate the results of firing tests on

samples 679 and 680.

MINERAL WOOL--TEST RESULTS

Mineral wool, a calcium silicate glass in the form of fine fibers, is a

processed fibrous material resembling loose wool. The principal use of mineral wool is as an insulating agent. Mineral wool, or a similar insulating

agent, is of prime importance to Alaskan construction because of the rigorous

climate; all insulating materials of this type presently are imported.

Mineral wool is manufactured by subjecting a calcium silicate melt to a

strong blast of air or steam.

As discussed in a previous report,7 chemical analyses of numerous samples

indicated that the components needed to produce mineral wool were present in

deposits of limestone and shale located in several areas.

Samples 622 and 629 of limestone and shale from the Windy-Cantwell area

were submitted to the Bureau of Mines for blowing tests. (See figure 9 for

sample location.) Chemical analyses of these samples are shown in table 2.

TABLE 2. - Chemical analyses of limestone and shale samples submitted

for mineral-wool blowing tests

Igni- NaCl

Sample CaO MgO SiO2 Al20 Fe2 0 tion C02 1 SO3 P Or + K0C2 Na2 0

loss KC12

622-limestone 51.0 0.14 0.8 0.70 1.2 41.2 39.4 0.18 0.002 0.16 - -

629-shale.... .4 .07 60.0 15.1 9.0 4.3 - .21 .32 - 0.66 0.4

1400° to 1,0000 C., direct combustion.

2 Determined by gravimetric methods.

7 Work cited in footnote 3 (p. 1), pp. 85-87, 91-115, 124-125.
~5\ ~-\ -- 50-570 'b:1 I I//

500 1000,' - LEGEND

o S, S oo

tje/nsitrudd k Igneous

6\\1

\ \ 5o10<

608

\ 6 7 / c i ,o 200

h1 scle, Feet

606^^ ©

12

LEGEND

+-- Granite intrusive

'-': Alluvial deposit

UI Cantwlel formation

ol Glaciol moraine,

outwash, i gravel

Shale 8 conglomerate

L~-I Basic lova flows 8 tuffs

Limestone, doshed

Q' where inferred

Argillite, shole, limestone, quartzite,

conglomerate, ,

greenstone

656 Sample number

-- Caot trail

-io

... + + - ± + + + ., . + / 4- > 4-. L

++. ;+ . . . . ... .- .-. 4 -. /. 

Fog as%/

/ imestone r / + / ov

+ + + + . ......

·1 -//,> /

/~~ o#I / i ,idylmstn '

/ /,6766

/% /' / A ' 6 '

\ 

/, ca : 7 656 652 ... - . -- 6 

a rv1±-; 4

i,a 'r 03⁄4

, D~vro 670

4 * + -r

++

± -- .i +± ± * - + +

4+ 1 u+ + -< -

'IO

_x __ -

/ l r@

I

0 I 2 3

Scale, Miles

Geology from USGS mop

-- 40

r2700' elevation 639 636A

-- 638

4 6A6 636

-,6A 632

\ o 629

624

~623

0 lOn 2000

Sele. C Feel

. - . .

.-. . - -

FIGURE 9. - Geologic and Sample Maps, Cantwell-Windy-Foggy Pass Area.
13

The limestone and shale were blended in various proportions for blowing

tests. The results are quoted as follows:

"Several of the mixes produced acceptable wool as evaluated by laboratory

methods. We consider wools from about 3 to 10 or 12 microns in average fiber

diameter to be in the proper range. From a competitive and economic standpoint

'included shot' should preferably be less than 50 percent by weight. Iron is

rather high in the shale sample but since sulfur is low there is little likelihood of forming enough hydrogen sulfide to give the wool an offensive odor.

"These data (table 3) show that a mix of 45 to 50 percent shale with the

balance limestone produces the optimum mineral wool. Fast pours may be made

in this range, the shot contents are not excessive and the temperatures,

although high, are not out of line. Above 2,800° F., fuel requirements and

corrosion on equipment accelerate rather rapidly."

TABLE 3. - Mineral wool from Alaskan shale and limestone

Melting

Percent by Steam temper- Time, Percent shot Fiber

Test wei ht p.s.i. ature, sec- Free Included diameter, Remarks

Shale CaCO3 F. onds microns

30 80 20 - 2,760 - - - - Too viscous.

37 70 30 42 2,950 45 11 - - Very coarse wool.

38 70 30 48 2,995 60 11 - 16 Coarse, brittle.

35 60 40 45 2,870 50 9.5 32 13 Slightly coarse.

36 60 40 44 2,900 46 15 - - Coarse.

31 50 50 44 2,700 34 9 36 11 Fair wool.

32 50 50 48 2,760 36 10 36 14 Coarse.

33 50 50 40 2,810 34 15 42 10.5 Good wool.

41 50 50 40 2,900 22 15 50 9 Do.

42 50 50 42 2,670 30 16 41 13 Somewhat coarse.

49 45 55 42 2,760 30 14 56 9 High shot.

50 45 55 40 2,800 20 17 46 9 Good wool.

51 45 55 32 2,850 27 13 42 8 Do.

39 40 60 45 2,700 33 17 52 11 High shot.

40 40 60 45 2,600 27 19 45 13 Slightly coarse.

47 40 60 40 2,690 29 20 47 8 Fair wool.

48 40 60 44 2,650 21 - - High shot.

43 35 65 42 2,750 24 - - - Too basic.

44 35 65 42 2,700 25 - - - Do.

45 35 65 42 2,830 - - - Do.
14

CEMENT

Specifications

Portland cement is made by burning to a clinker a finely ground mixture

of calcareous and argillaceous materials having an approximate composition of

70 to 75 percent CaCO ; 20 percent SiO2 , Al 0 , and Fe203; and 5 percent or

less MgO, alkalies, and other impurities. After cooling, the clinker is ground

to 80 percent minus 325-mesh.

Most specifications require portland cement to meet standards set by the

American Society for Testing Materials (ASTM). The ASTM classifications

include five types of portland cement.s The most common is Type II, used in

general concrete construction that will be exposed to moderate sulfate action

or when moderate heat of hydration is required. In addition to ASTM standards,

cement purchasers often specify other requirements in cement; the most common

of these is a maximum allowable amount of Na20, KOO, and MgO.

Limestone, or its equivalent, and clay or shale furnish the lime, silica,

alumina, and iron required for cement. Sometimes small additions of silica

sand and iron ore are necessary. Gypsum is added as a retarder in quantities

of 2 to 3 percent and ground with the clinker. Only test results of the two

major components of portland cement (limestone and shale) are described in

this report. Should a cement plant be constructed in the railbelt area, a

local source of high-silica material probably could be found; importing gypsum

and a high-iron component might be necessary.

The suitability of limestone or shale for producing cement is partly

dependent on the content of magnesia, alkalies, and alumina compounds. More

than 5 percent magnesia is objectionable in cement (ASTM maximum allowable for

Type II cement) because it may cause expansion as the concrete ages. The relative amount of magnesia present in the raw material constituents is increased

in the finished cement by eliminating carbon dioxide, water, and organic

matter during calcination. Therefore, to keep magnesia below the specified

5 percent, the raw mix should not exceed 3.2 percent MgO. Alkalies should not

be present in excess of 1 percent because they may react with silicates, also

resulting in expansion of the concrete.

Foggy Pass Limestone

A number of limestone and shale deposits were examined and sampled as

part of the search to find materials suitable for portland cement. Results of

studies conducted through 1950 were described in Report of Investigations 4932.

Only one deposit was considered worth further study. It is known as the Foggy

Pass limestone and is approximately 15 miles northwest of Cantwell, Alaska.

Investigations of shale deposits that might be used with Foggy Pass limestone to manufacture cement were confined to the immediate vicinity of the

Foggy Pass-Cantwell area.

sAmerican Society for Testing Materials, 1958 Book of ASTM Standards:

Philadelphia, Pa., pt. 4, pp. 1-5.
1

15

Location and Accessibility

The Foggy Pass limestone is located near the headwaters of the West Fork

of Windy Creek within the Alaska Range (fig. 9). The deposit can be reached

by a 15-mile tractor trail from the Alaska Railroad station at Cantwell. A

road, following the general course of this tractor trail from Cantwell to a

ranger cabin on Windy Creek, thence up Windy Creek to the deposit, could be

built with relative ease. A railroad spur route probably would parallel

Windy Creek from the present rail crossing of Windy Creek at Mile 323. Difference in elevation between the present railroad grade and the lowest limestone

exposures along the West Fork of Windy Creek is about 800 feet. The deposit

lies within Mount McKinley National Park. Unlike other national parks, prospecting and mining are permitted under certain conditions and regulations;

these are best summarized by the following excerpts from a publication

entitled Alaska Mining Laws:9

"Prospectors and miners may enter the Park and explore for mineral.

locations.

"Under an act of Congress approved January 26, 1931, the Secretary of the

Interior is given authority to prescribe regulations for the surface use of

any mineral location in the Park, and he may require the registration of all

prospectors and miners who enter the Park, but no resident of the United

States who is qualified under the mining laws of the United States applicable

to Alaska shall be denied entrance to the Park for the purpose of prospecting

or mining."

Physical Features and Climate

The limestone deposit is near the head of the wide, glaciated, northsouth valley containing the West Fork of Windy Creek. The West Fork of Windy

Creek swings east near the entrance to Foggy Pass until it joins Windy Creek;

below the confluence, Windy Creek flows southeastward to the Jack River.

Mountain slopes in the area are steep, with talus outwash fans at their

bases. The slopes above the talus are generally bare; vegetation, where

present, consists of low brush along water courses and moss and grass on the

gentle slopes.

The Foggy Pass limestone deposit is cut at an angle nearly normal to its

strike by the valley of the West Fork of Windy Creek. The deposit rises on

either side of the valley to form part of north-south trending ridges paralleling the West Fork of Windy Creek.

Subzero temperatures are expected in the Foggy Pass area from November

through April. Freezing temperatures may occur in any month of the year; temperatures range from minus 50° to 80° F.

9Roden, Henry, Alaska Mining Laws: Jessens Print, Fairbanks, Alaska, Rev.

1935, p. 22.
16

Rain and fog are frequent during the summer months. The average annual

precipitation is 20 inches. Snow may be expected between September and June.

General Geology

The Foggy Pass limestone deposit is the eastern end of a band of Middle

Devonian limestone,l 0 exposed from east of the West Fork of Windy Creek to the

head of Bull River. The limestone is part of a series of sedimentary rocks

composed of shale, argillite, conglomerate, limestone, quartzite, slate, and

graywacke.

Description of Deposit

The deposit is a dense, fine-grained, dark-gray to blue-gray recrystallized limestone. The strate are folded locally and contorted, but the degree

of shattering is slight. Networks of calcite veinlets are abundant. Dips and

strikes of individual beds vary greatly but the deposit as a whole strikes

east and west and stands nearly vertical. The intricate folding of individual

beds has probably caused repetition of bedding so that the thickness of the

deposit can only be roughly estimated;ll indicated thickness, as sampled along

the West Fork of Windy Creek, is 3,100 feet.

Sampling Procedures and Results

Chemical analyses of five preliminary samples of the Foggy Pass limestone

deposit are shown in table 4. Alkali content of each sample in the table was

less than 0.01 percent.

TABLE 4. - Chemical analyses of five preliminary samples

of the Foggy Pass limestone deposit

Length, Ass - percent

Sample feet CaO MgO SiO2 Al2 03 FegO3

163............. 13,000 51.4 0.35 4.1 1.15 0.43

164 .............. 1,000 47.1 .75 7.7 2.2 .68

165 .............. 1,200 49.8 .25 5.9 1.6 .58

166 ............... 1100 50.3 .65 5.4 1.6 .51

167.............. 1,100 51.4 .40 4.0 1.3 .50

1 Talus sample.

Favorable analyses of preliminary samples led to extensive sampling of

the Foggy Pass limestone during the 1951 field season. Representative samples

(501 through 570) were taken from channels 50 feet in length, cut along the

limit of the West Fork of Windy Creek across the deposit width.

l°Capps, S. R., Geology of the Alaska Railroad Region: Geol. Survey Bull.

907, 1940, p. 102.

1 Moxham, R. M., West, W. S., and Nelson, A. E., Cement Raw Materials

Available to the Windy Creek Area, Alaska: Geol. Survey Mimeographed

Rept., 1951, 38 pp.
,'A

0

17

Large talus accumulations at the toe of the

steeply rising deposit (fig.

10) afforded the opportunity

to obtain representative

samples both across the

width and along the strike

of material above the talus

accumulation. Samples 571

through 603, each representing 100 feet of length, were

collected from the talus

accumulation. Other samples

were 604, taken across an

outcrop island, and 605,

taken across a portion of

talus accumulation on the

west limit of the West Fork

of Windy Creek Valley

(fig. 9).

Samples were taken in

large volume, mechanically

crushed, and then split at

the site to facilitate shipment to the Juneau Experiment Station. Chemical

analyses of samples 501

FhoA..-h-L AC ova r ;

,rw

A' ~' ." 4

0,0

pi~ g" ~ 11 I - . 1 . . . I . - 1- I 11

table 5.

Conclusions

The Foggy Pass limestone deposit is of suitable

composition and of ample

quantity to be used as the

main constituent in portland

FIGURE 10. - Outcrop (Above) and Talus (Below) cement. The limestone meets

of Foggy Poss Limestone. limits set for low-alkali

cement, but some care would

be necessary in mining to maintain low alkali in the final product. The talus

accumulations are estimated to contain at least 14 million tons of already

broken limestone. This amount would be sufficient to manufacture about 56 million barrels of cement (376 pounds of cement per barrel).

Shale Deposits, Cantwell-Windy-FoRRy Pass Area

Numerous deposits of shale in the Cantwell-Windy-Foggy Pass area are of

potential use in portland cement.
Sample

501.......

502.......

503.......

504.......

505.......

506.......

507.......

508.......

509.......

510.......

511.......

512 .......

513.......

514.......

515.......

516 .......

517.......

518.......

519.......

520.......

521.......

522.......

523.......

524.......

525.......

526.......

527.......

528 ......

529.......

530.......

531.......

532.......

533.......

534.......

535.......

536.......

537.......

538.......

539.......

540.......

541.......

542.......

543.......

544.......

545.......

CaO

43.8

31.0

47.8

47.6

51.4

52.2

52.2

52.6

52.4

21.6

50.8

50.6

50.6

50.2

50.0

48.4

48.3

48.0

47.0

47.4

46.4

42,7

46.8

49.4

49.2

49.5

51.0

50.0

48.5

48.0

48.6

47.0

44.2

47.1

49.6

40.1

46.6

49.0

46.8

50.4

49.0

49.4

49.6

49.5

46.9

MgO

1.1

2.0

1.45

1.5

1.8

1.45

1.3

1.4

1.65

1.3

1.6

2.0

1.65

2.45

2.0

1.8

1.7

1.65

1.55

1.4

1.45

2.25

2.1

1.8

2.0

1.8

1.5

1.7

2.2

2.3

2.5

1.8

1.8

1.4

1.9

2.4

1.7

1.5

1.9

1.4

1.8

1.7

2.9

2.0

2.3

Sio02

9.24

24.0

6.4

6.4

1.86

1.14

1.74

1.24

3.26

21.3

2.72

2.20

2,40

4.00

3.50

4.8

5.3

5.5

7.4

7.1

8.4

10.1

6.4

5.0

5.9

4.7

3.4

3.6

4.6

5.5

5.4

7.8

10.0

8.0

4.4

14.0

6.9

5.5

6.1

5.4

4.8

3.6

2.6

3.6

6.1

AlO2

3.8

7.1

2.1

2.0

1.15

1.0

1.0

.72

1.0

14.6

1.38

1.47

1.57

2.07

2.33

2.55

2.78

2.98

3.11

3.73

3.95

4.90

3.23

3.05

2.63

2.93

2.57

2.45

3.03

3.03

3.15

3.05

4.05

3.3

2.3

5.85

3.75

3.60

3.7

2.15

3.05

2.3

1.75

2.50

4.25

Fe203

1.9

4.4

1.1

1.1

.58

.58

.58

.58

.58

11.4

1.02

.73

.73

.73

.87

.95

1.02

1.02

1.09

1.17

1.45

1.60

.89

.95

.87

.87

.73

.95

.87

.87

.75

.96

1.45

1.0

.60

1.45

.65

.50

.90

.65

.95

.60

.65

.60

.75

18

TABLE 5. - Chemical analyses of Foggy Pass limestone, percent

Ignition

loss

36.6

26.6

39.2

39.4

42.2

42.8

42.6

42.6

42.7

21.9

41.7

42.6

42.6

41.3

41.6

40.5

40.2

40.2

38.8

38.8

37.6

36.1

39.2

42.4

41.1

40.4

41.2

40.8

40.6

40.4

40.3

38.3

36.8

38.4

41.2

34.3

38.8

39.4

38.8

41.2

40.2

40.6

41.9

41.6

39.6

02O1

36.0

25.4

38.8

39.0

42.2

42.4

41.7

42.1

41.7

17.4

40.8

41.8

41.4

40.5

40.8

40.0

39.4

39.5

38.1

38.1

37.6

36.1

39.0

41.8

41.1

40.3

40.9

40.4

40.6

39.8

40.0

38.0

36.6

38.3

40.8

33.8

38.6

39.2

38.8

41.1

39.8

39.9

41.7

41.4

38.8

SOS

1.02

1.26

.52

.54

.22

.20

.30

.32

.26

7.24

.74

.30

.28

.42

.48

.50

.54

.56

.62

.66

.14

.22

.07

.06

.06

.07

.05

.06

.07

.07

.06

.08

.11

.06

.03

.12

.06

.06

.06

.01

.51

.42

.31

.36

.62

PAO

0.04

.07

.018

.016

.007

.014

.018

.019

.03

.25

.03

.016

.018

.025

.023

.02

.025

.03

.04

.02

.013

.015

.023

.03

.035

.03

.019

.020

.020

.020

.025

.030

.032

.029

.016

.046

.035

.032

.030

.023

.025

.020

.020

.019

.018

NaCI

+

KC -

0.18

.80

.10

.04

.16

.10

.70

.80

.52

.62

.58

.41

.62

.18

.14

.40

.90

1.34

1.00

.86

.82

.24

.36

.62

.14

<.01

<.01

<.01

.16

<.01

.44

.92

.88

.90

1.2

.74

.92

1.2

.46

<.01

-

0.32

.33

.23

.31

.38

Na. OR

-

0.30

.26

.32

.41

.38

I

-

- -- See footnotes at end _ . _ *« or raoDe.
Sample

546 ......

547.......

548.......

550.......

551.......

552.......

553 .......

554.......

555.......

556.......

557 .......

558.......

559.......

560 .......

561 .......

562.......

563.......

564.......

565.......

566.......

567.......

568.......

569.......

570.......

571.......

572 .......

573 ......

574.......

575 .......

576 .......

577.......

578.......

579 .......

580.......

581.......

582.......

583.......

584.......

585.......

586.......

587.......

588.......

589 .......

590.......

591.......

592.......

CaO

48.7

48.1

47.4

47.6

47.8

47.8

47.8

48.1

48.6

48.9

42.2

45.1

48.6

49.1

43.5

46.3

47.1

47.4

50.0

52.3

48.4

48.0

49.7

48.3

51.6

51.4

50.8

49.7

51.0

50.0

49.5

49.8

51.4

51.4

48.8

48.5

48.4

49.6

50.6

49.2

43.0

46.2

44.4

43,0

43.8

47.0

MgO

2.4

2.9

1.1

1.6

1.95

1.9

1.65

2.4

1.25

.85

2.3

2.4

1.45

1.9

2.7

2.0

2.3

1.9

1.5

1.5

1.5

2.0

1.8

1.3

1.43

.73

1.48

2.75

1.05

1.23

1.23

1.60

1.23

1.43

1.77

1.81

1.45

1.41

1.35

1.20

2.18

2.02

1.78

1.45

1.65

1.9

SiO9

4.0

5.2

6.8

6.0

8.8

7.0

7.4

6.2

3.5

3.6

4.1

5.8

3.9

5.2

5.4

4.4

4.6

5.0

4.9

4.7

11.3

8.4

5.0

5.0

2.8

2.8

2.4

3.3

2.4

3.3

2.8

3.5

2.4

2.4

4.8

5.1

4.7

3.8

3.2

4.5

5.8

7.1

9.3

9.9

10.5

6.2

Al 03

2.05

3.0

3.7

3.25

3.85

3.55

3.05

2.95

2.55

2.35

2.95

3.85

2.95

2.8

4.0

4.3

4.2

3.7

2.65

2.55

3.2

3.1

2.45

3.05

1.77

1.55

1.6

1.92

1.85

2.2

2.77

2.5

1.62

1.77

3.03

2.69

2.9

2.77

2.02

2.45

4.25

3.32

4.2

4.4

5.1

3.7

Fearn

0.95

.80

.90

.95

1.15

1.15

.85

.85

.85

.85

1.45

1.15

.85

1.0

1.4

1.1

1.0

.90

.65

.75

.80

1.0

.75

.85

.43

.35

.50

.78

.35

.50

.43

.50

.28

.43

.57

.71

.50

.43

.28

.35

1.15

.78

1.0

1.0

1.3

1.1

19

TABLE 5. - Chemical analyses of Foggy Pass limestone, percent (Con.)

Ignition

loss

40.5

39.8

38.0

39.9

37.6

39.2

39.8

39.5

40.8

40.7

40.2

39.7

40.7

39.8

39.8

39.9

40.6

40.5

40.1

40.8

40.2

39.9

40.6

40.6

42.2

42.1

42.0

41.8

42.2

42.1

41.8

40.9

42.8

42.4

40.1

40.4

39.1

40.8

41.4

40.6

37.7

39.2

37.8

37.6

37.6

39.4

CO2 1

40.2

39.6

37.4

39.4

37.1

38.8

38.4

38.7

40.6

40.6

40.2

39.3

40.4

39.6

39.5

39.8

40.2

40.2

39.8

40.2

39.8

39.6

40.2

40.2

41.8

42.0

41.8

41.6

42.0

41.8

41.4

41.6

42.6

42.1

39.9

40.3

37.6

40.6

41.1

40.2

36.5

38.4

36.8

36.0

35.9

38.8

SOs

0.75

.45

.67

.73

1.1

1.0

.95

.69

.45

.42

.60

.67

.53

.68

1.0

.64

.65

.76

.72

.67

1.1

.80

.57

.35

.11

.06

.15

.22

.13

.07

.15

.21

.12

.08

.21

.20

.22

.18

.15

.38

.18

.62

.37

.47

.24

.25

0.019

.026

.027

.027

.039

.030

.030

.030

.023

.017

.021

.023

.025

.019

.021

.022

.026

.032

.028

.030

.041

.028

.016

.018

.014

.020

.015

.028

.023

.025

.025

.023

.020

.023

.028

.041

.039

.030

.037

.028

.025

.023

.020

.025

.025

.028

NaC1

+

KG I'

0.56

.20

.14

.76

.50

.70

.24

.08

.10

.44

.84

.70

<.01

1.0

.86

.80

.50

.62

.42

.24

.52

.48

.22

<.0l

.62

.30

.82

1.0

.40

.46

.56

.14

1.1

1.1

1.1

.40

.96

.48

.06

1.1

.66

<.01

.70

.64

.10

.70

K02 s

I

3

L

-·

I)

· 1

3

-r

-·

3

3

-r

Na2 0o

See footnotes at -- A -9 i -U I - IU UJ. LCLUJ.I.
TABLE 5. - Chemical analyses of FoRgy Pass limestone, percent (Con.)

Igni- NaC1

Sample CaO MgO SiO2 AL2 , Fe 0 3 tion C02 1 SOC P205 + K2 O NaaO2

loss KC1 2

593 ...... 47.0 1.6 6.3 4.2 1.1 39.0 38.0 0.33 0.035 0.70 - -

594 ....... 47.4 1.5 4.7 3.55 .95 39.8 39.2 .26 .037 .24 - -

595........ 45.8 1.35 4.7 2.97 .73 40.4 40.0 .16 .028 .44 - -

596 ....... 46.8 1.9 4.7 2.97 .73 40.4 39.8 .15 .025 .50 - -

597 ....... 40.8 1.65 3.6 2.85 .65 41.1 40.7 .12 .028 .74 - -

598....... 48.6 1.5 4.2 3.47 .73 41.0 40.8 .12 .023 .54 - -

599 ....... 49.2 1.65 2.8 2.27 .73 41.6 41.4 .14 .023 .40 - -

600 ....... 48.0 1.9 3.5 2.37 .73 41.0 40.8 .17 .020 .68 - -

601 ....... 46.2 1.9 3.7 2.47 .73 41.6 41.1 .07 .020 .62 - -

602 ....... 48.1 1.9 3.4 2.67 .73 41.6 40.7 .09 .018 .62 - -

603 ....... 48.1 1.5 3.9 3.2 .80 40.8 40.2 .08 .032 .26 -

604 ....... 46.9 1.65 3.0 2.47 .73 41.4 41.3 .06 .030 .64 - -

605 .... 46.9. 1.3 6.5 3.6 1.0 39.4 39.1 .08 .016 .08 - -

1400° to 1,000° C., direct combustion.

2 Determined by gravimetric methods.

Location and Accessibility

All shales sampled are in the vicinity of the Foggy Pass limestone

deposit and would be accessible from the West Fork of Windy Creek. Locations

of outcrops and samples are shown on figure 9.

General Geology

The shales lie within a belt of rocks about 5 miles in width tentatively

assigned to the Jurassic age.l2 This belt, estimated to exceed 5,000 feet in

stratigraphic thickness, is comprised chiefly of shale and conglomerate with

lesser amounts of argillite and graywacke, all of which have been closely

folded, crushed, and faulted. They are bounded on the north and are in fault

contact with rocks of Devonian age.

Sampling Procedures and Results

Bureau of Mines engineers obtained channel samples from a number of shale

outcrops in the Cantwell-Windy-Foggy Pass area. These samples were all preliminary to determine which shales would be suitable for use in portland cement.

No attempt was made to determine the uniformity or size of the various deposits; each deposit or part of a deposit was represented by one sample. Since

the shale deposits in the area are extensive, quality of the shale probably

would be important in determining mining location.

All of the shale samples taken during the investigation contained less

than the maximum permissible limit of magnesia, but some samples contained

more than the maximum limit of alkalies permissible for low-alkali cement. The

chemical analyses of all shale samples are presented in table 6.

12Capps, S. R., The Eastern Portion of Mount McKinley National Park: Geol.

Survey Bull. 836(d), 1932, p. 263.

20
Sample

606......

607......

608......

609......

610......

611......

612......

613 .....

614......

615......

616......

617......

618. ....

619......

620......

621......

623......

624......

625......

626......

627......

628......

629......

630......

631......

632......

633......

634......

635......

636......

637......

638......

638-A....

639......

640......

641......

642......

643......

644......

645......

646......

647 .....

648.....

649......

650......

651......

CaO

<0.05

<.05

<.05

<.05

<.05

<.05

<.05

<.05

<.05

1.2

.8

1.2

1.8

.4

.2

.6

1.0

1.2

1.4

1.8

.6

.8

.4

.6

1.4

1.6

1.0

1.2

1.54

.52

.20

.48

.40

.48

.72

7.52

.80

1.02

1.10

3.86

.96

.76

1.14

1.14

1.60

.64

MgO

1.95

2.1

1.65

1.95

2.0

1.9

1.9

1.95

2.1

.13

.14

.09

.12

.15

.21

.19

.13

.13

.07

.11

.11

.06

.07

.07

.11

.12

.11

.14

2.1

1.8

1.2

.9

.3

.5

2.2

.5

.6

.3

.04

.4

.3

.4

.09

.2

.6

1.5

sio

66.5

59.4

63.8

64.7

64.0

64.0

64.4

63.4

63.0

59.8

59.3

59.4

58.8

57.5

59.7

63.8

57.1

57.9

60.0

56.6

57.6

59.6

60.0

61.5

57.5

61.6

68.2

57.2

57.1

55.3

70.3

62.1

60.2

59.0

57.5

70.4

57.8

57.6

58.5

55.6

66.6

55.7

59.4

68.5

65.1

59.2

Als0o

15.2

15.95

17.9

17.0

17.15

16.9

17.45

16.2

16.0

16.8

17.0

18.1

16.9

16.8

21.2

14.1

16.5

14.0

13.4

12.9

14.0

16.5

15.1

14.0

14.1

15.0

11.2

20.0

20.0

23.4

19.0

18.3

18.0

21.0

18.7

12.8

22.7

18.1

19.3

14.2

15.2

21.4

22.1

13.4

16.1

19.5

21

TABLE 6. - Chemical analyses of shale samples, percent

Fe2 0

6.4

5.95

6.4

6.55

6.55

7.3

6.75

7.5

7.3

8.05

8.45

8.05

8.8

7.75

8.65

8.8

8.05

8.1

8.45

8.0

7.5

9.8

9.0

8.8

8.1

8.05

8.0

7.8

6.8

7.6

6.0

6.0

6.0

6.8

6.0

3.8

7.0

6.6

6.8

4.0

5.0

6.8

7.2

4.4

5.4

7.0

Ignition

loss

3.8

3.8

4.6

4.4

3.8

3.8

3.8

4.4

4.1

4.3

4.3

4.2

4.1

3.9

4.1

4.6

4.0

4.1

4.5

3.9

3.8

4.1

4.3

4.4

4.0

4.0

4.0

3.8

6.42

6.94

4.08

4.20

4.54

4.64

4.58

6.90

5.36

5.22

5.40

5.84

3.00

4.38

4.40

5.34

4.14

5.24

SO0

0.19

.17

.21

.28

.19

.14

.17

.24

.28

.24

.28

.24

.62

.26

.19

.24

.32

.34

.41

.29

.24

.20

.21

.28

.28

.18

.17

.15

.25

.19

.21

.27

.29

.20

.22

.17

.20

.18

.28

.41

.22

.14

.18

.07

.25

.24

P

2 0r

0.28

.47

.30

.34

.28

.34

.27

.40

.27

.37

.41

.32

.35

.32

.16

.15

.21

.26

.23

.35

.35

.37

.32

.28

.23

.30

.32

.34

.32

.32

.32

.28

.28

.34

.39

.40

.34

.28

.37

.28

.28

.32

.32

.34

.28

.30

NaCl+KCll

0.86

.93

.66

.60

.61

.58

.53

.50

.48

.92

1.0

.74

.82

.86

1.0

.56

.72

.90

.38

.46

Ks01

0.44

.90

.72

.62

.47

.45

.51

.57

.35

.46

.60

.58

.60

.66

.98

.61

.53

.60

.62

.49

.36

.38

.60

.63

.60

.40

-

Na2 0o

0.42

.51

.38

.33

.25

.24

.27

.30

.18

-

.38

.36

.43

.50

.40

.20

.60

.36

.61

.61

.43

.40

.41

.58

.49

.39

.36

See footnote at end of table.
22

Sample

606...

607...

608...

609...

610...

611...

612...

613...

614...

615...

616...

617...

618...

619...

Sample

length,

feet

TABLE 6. - Chemical analyses of shale samples, percent (Con.)

Sample CaO MgO SiO2 AleOs FeOa8 Ignition SO3 PaO NaCl+KC11 K-0' Naa0 1

loss

652...... 0.92 0.8 61.0 19.5 7.0 4.84 0.22 0.32 0.52 - -

653 ...... .24 1.2 60.4 20.6 7.0 4.96 .20 .32 .58 -

654....... 1.8 .29 62.6 22.7 7.5 5.2 .17 .30 .82 - -

655 ...... 2.2 .41 61.2 17.0 6.2 6.2 .28 .26 .92 -

656 ...... 4.0 .21 70.2 12.9 4.9 4.4 .20 .28 .82 -

657 ...... 1.6 .36 76.2 12.2 4.0 4.8 .21 .26 .76 -

660...... 1.4 .14 68.0 16.6 6.0 3.8 .22 .28 .26 -

661 ...... 1.0 .22 57.2 24.0 7.6 4.0 .24 .27 .32 -

662 ...... .8 .43 69.0 16.6 6.0 4.2 .21 .16 .34

663 ...... 2.0 .36 72.2 12.4 4.2 6.4 .28 .13 .40 - -

664...... 1.4 .29 70.8 11.3 4.3 5.2 .18 .28 .46 - -

665 ...... .8 .43 69.8 16.2 5.0 4.6 .20 .32 .58 - -

666 ...... .6 .58 70.0 15.0 4.8 4.8 .21 .39 .70 - -

667 ...... 1.0 .21 74.4 13.9 4.9 3.8 .21 .30 .84 -

668 ...... 1.2 .15 63.0 20.9 6.9 3.6 .19 .28 1.0 -

669 ...... .8 .07 70.0 17.2 5.0 4.0 .21 .28 .68 -

670 ...... 1.4 .21 72.0 14.0 4.8 5.2 .22 .28 .58 -

1Determined by gravimetric methods.

Table 7 briefly describes visual observations made of the various shale

outcrops and the samples taken.

TABLE 7. - Log of shale samples, Cantwell-Windy-Foggy Pass area

100

100

100

100

100

100

100

100

100

100

50

50

50

90

Individual sample

description

Group description

Shale samples taken along a

small tributary to the West

Fork of Windy Creek near

Foggy Pass (fig. 9). This

deposit is within a very

short distance and easily

reached from the probable

road route to the Foggy Pass

limestone deposit.

A shale outcropping along

Windy Creek located adjacent

to the second tractor trail

crossing downstream from the

ranger cabin (fig. 9). The

shale is black in color and

grades from thin-bedded to

massive badly fractured zones.

A few pyrite crystals were

observed.
Sample

F 620...

621...

623...

624...

625...

626...

627...

628...

629...

630...

631...

632...

633...

634...

635...

636...

637...

638...

638A..

639...

640...

641...

642...

23

TABLE 7. - LoR of shale samples, Cantwell-Windy-Foggy Pass area (Con.)

Sample

length,

feet

50

500

100

100

100

50

50

100

100

100

50

50

100

100

100

43

100

100

100

100

100

85

54

Individual sample

description

A 50-foot bed of shale located

between the third and fourth

tractor trail crossing of

Windy Creek, downstream from

the ranger cabin (fig. 9).

A shale outcrop 500 feet in

width along the south limit

of Windy Creek, just downstream from the point at

which the tractor trail

leaves Windy Creek to enter

the valley of a small

tributary (fig. 9).

Black sheared shale, calcite

on slickensides.

do.

do.

do.

Bands of limy shale with some

grading almost to limestone,

Dark-brown to black shale,

exposure poor.

Dark shale.

do.

do.

Graywacke.

do.

Black, thin-bedded shale.

do.

do.

Black, thin-bedded shale

grading to a more sandy

phase.

Black thin-bedded shale.

Black shale with some

igneous intrusion.

Black shale.

do.

do.

A black, thin-bedded shale 65

feet in width along Little

Windy Creek just above its

confluence with Windy Creek

(fig. 9).

Group description

.

Shale samples taken along the

cut of the Alaska Railroad

between Mile 321 and 322

(fig. 9).

v
Sample

643...

644...

645...

24

646...

647...

648...

649...

650...

651...

652...

653...

654...

TABLE 7. - Log of shale samples, Cantwell-Windy-Foggy Pass area (Con.)

Sample

length,

feet

150

100

95

100

100

100

200

150

100

80

100

80

}

Interbedded graywacke and

shale 150 feet in width

exposed along the limit of

Little Windy Creek immediately upstream from the

intrusive dike ending sample

644 (fig. 9).

Interbedded graywacke and

shale. Contains one 18-inch

dike of foreign materials.

Black sheared shale with a

small amount of graywacke.

Interbedded black shale and

purple graywacke stained

yellow in places by limonite.

Thin-bedded gray-to-black

shale which weathers yellow

to brown and shows some scattered pyrite grains. The

deposit strikes N. 60° to

70° E. and dips 70° S.

Interbedded black shale and

graywacke, sheared and contorted, thin-bedded, contain

a 2.0-foot igneous dike. The

strike ranges from N. 60° to

65° E., and the dip ranges

from 750 N. to 75' S.

Thin-bedded black shale.

Black sheared and contorted

shale.

do.

do.

Individual sample

description

.=

. . . - .

Group description

A thin-bedded, sheared black

shale and graywacke that

strikes N. 65° E. and dips S.

The deposit is exposed along

the limit of Little Windy

Creek, approximately 500 feet

upstream from sample 642.

The samples represent a section 195 feet in width, ending on the hanging-wall side

at the contact with an

intrusive dike (fig. 9).

These samples were taken along

a small gully 0.5 mile NE. of

Alaska Railroad crossing

(fig. 9).

I

Samples 649 through 654

represent shale deposits

exposed along the lower

portion of Windy Creek

(fig. 9).

/
Sample

655...

X

.- = = - =_ - .- -.--

25

TABLE 7. - Log of shale samples, Cantwell-Windy-Foggy Pass area (Con.)

656...

657...

660...

661...

662...

663...

664...

665...

666...

667...

668...

669...

670...

Sample

length,

feet

100

75

100

50

50

50

50

50

50

50

50

50

50

50

Individual sample

description

Black, thin-bedded,

contorted shale,

Gray-to-black shale interbedded with purple-gray

graywacke.

do.

Black shale,

Black shale.

Black shale,

dip 60° S.

Black shale.

do.

Black shale,

dip 80° N.

Black shale.

strike N. 63° E.

strike N. 65° E.,,

strike N. 65° E.,

Group description

This sample was obtained along

the south limit of Windy

Creek immediately above its

junction with Little Windy

Creek (fig. 9).

These samples were taken along

the limit of upper Little

Windy Creek (fig. 9). Sample

cutting commenced adjacent to

an igneous dike. The deposit

strikes about N. 800 E. and

dips 55° S.

Samples taken along the

Cantwell to McKinley Park

roadcut, just south of the

first Nenana River road

crossing from Cantwell

(fig. 9).

A group of samples taken from

a shale exposure along the

roadcut of the Cantwell to

McKinley Park highway. This

exposure is located about 600

feet upstream from the confluence of the Jack River and

Windy Creek; the Jack River

approximately parallels the

highway at this location

(fig. 9).

Black shale.

do.

do.

do.

S

INT. *U, OF MINES.PGH. .PA 3799