Bulletin No. 236 <WiflJA' Bcon°mic Geology, 37 

benes\B, Descriptive Geology, 42

DEPARTMENT .OF THE INTERIOR

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. WALCOTT, DIRECTOR

THE

BY

CHARLES W. ^VRIG-I-IT

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1904

CONTENTS.

Page.

Letter of transmittal...................................................... 7

Introduction.......................................... ,. .................. 9

Itinerary ............................................................. 10

Acknowledgments...........-............--.-.----------..--......... 11

Historical sketch......................................................... 12

Discovery............................................................ 12

Location of claims.......... '.......................................... 12

Neighboring creeks................................................... 12

Glacier Creek.................................................... 12

Bowlder Creek................................................... 12

Nugget Creek .................................................... 13

Bear Creek .............. J....................................... 13

Production .....~.....................^:............................. 13

Topography........................................ 1..................... 14

Mountains................ ................................'........... 14

Drainage ............................................................ 14

Geology .................................................................. 15

Introduction......................................................... 15

Sedimentaries........................................................ 16

Intrusives ................-....._...-................................ 17

Mineral occurrence................................................... 17

Glaciation ............................................... '. ........... 18

Economic geology ....... 1................................................ 19

Distribution of auriferous gravels...................................... 19

Classification of placers . ...........................................:.. 19

 Character of gravels .................. .<. ............................... 19

Assays of samples ........................................... t. ....... .20

Source of placer gold ................................................. 20

Developments............................................................ 21

Description of claims .................................................. 22

Porcupine Creek ................................................. 22

Delta claims ...-.'.............................................. 22

Cranston claim............................................... 22

Discovery claim.............................................. 23

Mix claim .................. 1................................ 24

Finley claim................................................. 24

McKinley Creek ................................................. 24

Chisholm claim .................."......................'...... 24

Woodin claim................................................ 25

Other claims................................................. 26

Nugget Creek placers............................................. 26

Creek gravels ................................................ 26

Bench deposits............................................... 27

3
4 CONTENTS.

Page.

Rainy Hollow mining district............................................. 27

Methods of mining ...............1....................................... 28

Ground sluicing............................................:......... 28

Hydraulicking....................................................... 29

Mining by elevators ................................................... 29

Sluice boxes ......................................................... '29

Water supply ............................................................. 30

Forests .......................-..................-.........-............'. -30

Trails and transportation ....."............................................. 30

Climate..-.....--.............-...--.....-.-.--........---.-.-....-...--.. 31

Summary......................--..--....----..-..--.....-...-..-......-- 31

Index ................................................................... 33
ILLUSTRATIONS.

Page.

PLATE I. Chilkat Peninsula, looking south from Mount Ripinski; Haines Mission in the foreground ......................................... 9

II. Map showing location of Porcupine placer district ................. 10

III. View of Porcupine, Alaska ...................................... 12

IV. A, Porcupine Creek at No. 1 above Discovery claim; B, The head

of Porcupine Creek, lookingsouth............................... 14

V. Geologic map of vicinity of Porcupine ............................ 16

VI. A, Bench deposit on Cranston claim; B, High bench deposit on

Woodin claim, McKinley Creek................................ 18

VII. A, Large flume, Discovery claim; B, Bucket elevator and sump

cut into bed rock, Discovery claim.............................. 20

VIII. A, Claim No. 1 above Discovery; B, High bench deposit on Finley

claim.....................:............................:...... 22

I.. A, Chisholm claim, McKinley Creek; B, McKinley Creek Canyon,

below Woodin claim........J.................................. 24

X. A, Hydraulicking at the head of Cahoon Creek; B, Hydraulicking

bench deposit on Woodin claim ................................ 26

FIG. 1. Map of Porcupine Creek, showing location of claims................. 21

2. Section across Cranston claim, showing side bench deposit........... 23

3. Section of Porcupine Creek at the Finley claim...................... 24

4. Section of McKinley Creek at the Woodin claim .................... 25

LETTER OF TRANSMITTAL.

DEPARTMENT OF THE INTERIOR, 

. UNITED STATES GEOLOGICAL SURVEY,

Washington, D. C., March 17, 1904.

SIR: I have the honor to submit herewith the manuscript and illustrations of a report entitled " The Porcupine Placer District, Alaska," 

by Charles W. Wright, and to recommend its publication as a bulletin. 

The Porcupine placer district lies in southeastern Alaska, adjacent 

to the international boundary, and the exploitation of its mineral 

wealth has, in a measure, been dependent on the definite settlement of 

the line separating Alaska and British Columbia. Now that the 

boundary is established, developments of the placer field will undoubtedly be rapidly extended. The district, though of no great extent, is 

easily accessible and promises to yield a good return if developed by 

economic methods.

Mr. Wright spent only three weeks in this field, and his studies were, 

therefore, by no means exhaustive. It is believed, however, that this 

presentation of the facts observed and of the tentative conclusions 

reached will be of value to the mine operators and prospectors. 

Very respectfully,

ALFRED H. BROOKS,

Geologist in Charge, 

Division of Alaskan Mineral Resources.

Hon. CHARLES D. WALCOTT,

Director United States Geological Survey.

7

BULLETIN NO. 236 PL. I

PENINSULA, LOOKING SOUTH FROM MOUNT RIPINSKI. 

Hames Mission in foieground.
THE PORCUPINE PLACER DISTRICT, ALASKA.

By CHARLES W. WEIGHT.

INTRODUCTION.

The Porcupine gold field, one of the most important placer districts 

of southeastern Alaska, lies in a rugged mountain belt.drained by the 

Chilkat, a river emptying into Lynn Canal. The district embraces an 

area of about 100 square miles,, its central point being approximately 

in latitude 58° 25' and longitude 136° 12'. (See map, PI. II.)

Placer gold was discovered on Porcupine Creek in 1898, and developments begun during the following year have been continued to the 

present day, with a rapid increase in the output of gold, which aggregates about $460,000. These placers lie close to the international 

boundary, and-their extensive development has been in a measure 

dependent on the final settlement of its location.

In 1899 the Geological Survey dispatched an expedition to explore 

the northern front of the St. Elias Range and the headwaters of White 

and Tanana rivers. This party, under the leadership of Mr. W. J. 

Peters, made its way inland by the Daltou trail, passing close to the 

then newly discovered gold placers of Porcupine, thus enabling Mr. 

Alfred H. Brooks, who was attached to the party as geologist, to make 

a cursory examination of a few of the claims on Porcupine Creek, the 

results of which were subsequently embodied in his report."

The growing importance of this district led to a demand for a more 

systematic examination, and to this investigation the writer was 

assigned. He was instructed to make a reconnaissance of the entire 

field and to study its mineral resources, geolog}-, and development, as 

far as time would'permit The field work occupied about three weeks, 

during which all claims on which any development work had been done 

were visited. There were no opportunities for accurate surveys, but 

as the region -had fortunately been surveyed by the International 

Boundary Commission, its contoured map was used as a base, and was 

supplemented by foot traverses. 1

"Brooks, Alfred H., A reconnaissance from Pyramid Harbor to Eagle City, Alaska: Twenty-first 

Ann. Kept.- Tji S. Geol.'Survey, pt. 2,1900, pp. 374-:37C.
10 THE PORCUPINE PLACES DISTRICT, ALASKA. [BULL. 2&5.

ITINERARY.

Leaving Seattle on June 23,1903, Haines Mission, Alaska, was reached 

four days later. This mission, established in 1881, is pleasantly situated 17 miles below Skagway, on the protected bay of Portage Cove, and 

is immediately surrounded by gently sloping land. Besides the native 

village of about 80 huts, there are several trading stores, a drug store, 

a comfortable hotel the "Northern" and large mission buildings. 

The War Department is establishing an army post 1 mile south of the 

town. A square mile or more of ground had already been cleared 

and barracks were being built at the time of the writer's visit.

From here the Porcupine gold field may be reached either by the 

Dalton trail, which starts at Pyramid Harbor, on the west shore of 

Chilkat Inlet, or by way of Chilkat River to the Indian village Klukwan, and thence up Klenini River, a west branch of the Chilkat, to 

Porcupine.

The latter route was chosen, and two natives with a boat were 

engaged to ascend the Chilkat. It was necessary, however, to wait for 

a favorable south wind, the rapid current rendering it impossible even 

to pole upstream without the help of a sail. This delay gave time for 

an investigation of Chilkat Peninsula, a strip of land extending 6 

miles south of Haines Mission (see PI. I), and in times past staked by 

prospectors for gold, copper, and iron, though nothing worthy of 

development has ever been found. The country rock is a muchcontorted slate, with intrusive masses of nearly black pyroxenite 

and hornblendite carrying an abundance of magnetic iron ore.

The portage of 1 mile to Pyramid Point, on the Chilkat, was made 

on the morning of June 29. Head winds encountered there made it 

necessary to pole the canoe along the shore for several miles to a point 

above the Chilkat village, Yendestaka, at the head of tidewater. This 

slow mode of progression permitted a study of the outcrops along the 

east bank, which were composed of dark intrusive rock similar to that 

exposed farther south on Chilkat Peninsula. The valley of Chilkat 

River between Yendestaka and Pyramid Point broadens to form 

McClellan Flats, a tide-water area of numerous channels and sand bars, 

approximately 2 miles wide. Above Kicking Horse and Takhin rivers, tributaries from the west, the valley decreases in width and the 

river is divided by many wooded islands. There is a marked con-' 

trast between the rounded, barren mountains to the east and the 

rugged, broken peaks, mostly covered with snow and glaciers, to the 

west, although on both sides of the river the mountains rise to an 

elevation of 4,000 to 6,000 feet.

Fifteen miles above Yendestaka is the small Indian village of Katkwaltu (place of-the gulls), on the east bank of the river. Six miles 

above Katkwaltu is Klukwan (the old town), at the mouth of Salmon
U. S.GEOLOCIGAL SURVEY BULLET IN NO. 236 PL. II

Clnlkxt \ >

Lake V\ --,x

MAP SHOWING LOCATION OF

PORCUPINE PLACER DISTRICT

BY CHARLES W. WlllGHT
WRIGHT.] INTRODUCTION. 11

River. This point is 22 miles, as the crow'flies, from Haines Mission, 

though by the river route the actual traveling distance is at least 30 

miles. A population of 500 was reported here in 1880, but at present 

the total is less than 100, and this only during the winter months. A 

mile and a half beyond is Wells Post, a station of the Northwestern 

mounted police, on the Canadian side of what was then the provisional 

boundary. A mining recording office was established here in 1900 for 

the benefit of the prospectors of Rainy Hollow and Bear Creek districts. The former lies 25 miles up Klehini River, which enters the 

Chilkat from the west at this point; the latter, 10 miles up the Chilkat. The establishment of the boundary farther inland, however, 

has since led to the withdrawal of this station. At this post the night 

was spent, the hospitalities of the camp being extended to the writer 

by Captain Rant. 

The following morning (June 30) the Indians were dispatched with

the baggage up the Klehini to Porcupine by canoe, while the writer 

crossed Chilkafc River and took the trail, following the north bank of 

the Klehini for 10 miles and then crossing the river to the town on the 

south slope of the valley.

Porcupine, a mining camp 550 feet above sea level, is situated on 

a bench about a half mile back from the river. The town, of about 

SO persons, consists of Dalton's trading store, the Lindsay Hotel, and a 

dozen or more houses and log cabins (see PI. III). During the winter 

mouths it is practically deserted, owing to the heavy snowfall, which 

prevents all operations.

After having given two weeks to a study of the placers of Porcupine Creek, July 18 and 19 were devoted to Nugget Creek, a tributary 

of Salmon River 20 miles above its mouth.

As the data collected during the few weeks spent in the district are 

far from complete, a full description of the geology and mineral 

resources of the region has not been attempted in this report. Nevertheless it is hoped that it may prove useful to those.who are developing the district.

ACKNOWLEDGMENTS.

The writer wishes to express his gratitude for the hospitalities and 

aid extended to him by the many prospectors and miners of the region. 

Though it would be impossible to give the names of all, he is under 

special obligations to Capt. J. M. O'Connor, of Haines; Mr. E. B. 

Hanley, Mr. S. W. Mix, and Mr. C. P. Gaboon, of Porcupine; Mr. 

Guy Lewis, of Nugget Creek, and Captain McDonald and Doctor 

Fraser, of Pleasant Camp. He is also much indebted for many valued 

suggestions to Dr. Arthur C. Spencer, of the.United States Geological 

Survey, under whose general direction the investigation was carried 

out.
12 THE PORCUPINE PLACER DISTRICT, ALASKA. [BULL. 236.

HISTORICAL SKETCH.

DISCOVERY.

Placer mining in the Porcupine district dates from the summer of 

1898, when locations were made by Messrs. Mix, Finley, and Wiley. 

These men, en route to the interior, took the Dalton trail, but, owing 

to high water and lack of provisions, were obliged to halt when only 

15 miles up Klehini River. They camped near Bowlder Creek, a tributary from the northwest, and found traces of gold in the stream 

gravels. Fording the Klehini to Porcupine Creek, a mile above Bowlder, they discovered richer gravels and obtained small nuggets of 

gold. After locating Discovery and the three claims above, which 

have since proved to contain the richest deposits in the district, they 

returned to Haines Mission to record their claims and obtain supplies. 

As a result of these discoveries nearly a thousand prospectors are said 

to have visited this creek during the autumn of 1898 and the spring of 

1899. In the summer of 1899, Porcupine had a population of 200, and 

probably as many more were camped along the various streams near by.

LOCATION OF CLAIMS.

Creek claims, 1,500 by 600 feet, were staked to the head of the 

Porcupine and its tributaries, McKinley, Marble, and Grizzly creeks, 

and a number of bench claims were located on the hillsides, some of 

them several hundred feet above the creek bottom. Other tributaries 

to Klehini River were prospected and many locations made, though 

the majority of these have since been abandoned, partly because of 

their position on the Canadian side of the provisional boundary of 1900.

NEIGHBORING CREEKS. 

GLACIER CREEK.

Of the creeks temporarily under Canadian jurisdiction, Glacier is 

the most important and the only one that has been carefully prospected 

or that has given promise of success. This creek was practically all 

located under the Alaskan regulations before the adoption of the 

modus vivendi, by which Americans were allowed to hold previously 

located claims, but owing to the uncertainty of conditions it has never 

been thoroughly developed. Those who did their annual assessment 

work have been pleased with the results obtained. The recent boundary decision throws Glacier Creek into Alaskan territory, and this will 

probably lead to activity during the season of 1904.

 BOWLDER CREEK.

Bowlder Creek enters Klehini River from the north, opposite Porcupine Creek. Here likewise a number of claims were staked under.
U. S. GEOLOGICAL SURVEY 

VIEW OF PORCUPINE, ALAbKA.
WEIGHT.] HISTORICAL SKETCH. 13

Alaskan regulations, but no developments were made, and no claims 

are held at present. Gold occurs in the gravels of this creek, but 

probably not in sufficient quantity to warrant mining operations.

NUGGET CREEK.

Nugget Creek, a tributary of Salmon (Tsirku) River, lies about 

20 miles from Klukwan and 6 from Porcupine, across the divide from 

McKinley Creek. It was discovered in 1899 by C. H.- Anway, who 

first found gold along the banks of Salmon River, and later discovered 

coarse gold in both Nugget and Cottonwood creeks, on which he 

located claims. Development work was not undertaken until 1902.

BEAR CREEK.

The last of the known gold fields in the Chilkat drainage basin is 

Bear Creek, a western tributary of Chilkat River, 40 miles north of 

Chilkat Inlet. Fifteen miles above its mouth Bear Creek is joined 

from the west by Clear Creek. Both of these streams caused excitement in 1900, but have not thus far been productive. This has been 

chiefly clue to the difficulties in controlling high water in the creeks, 

the extreme depth of bed rock, and the presence of quicksand. There 

are still a few miners on these streams, and the fact that they remain 

suggests the presence of payable gravel. This area is now Alaskan 

territory and many claims have been restaked by Americans, who will 

begin operations in the spring of 1904.

PRODUCTION.

The gold production of the placer'diggings on Porcupine Creek and 

its tributaries since their discovery in 1898 has been approximately 

as follows:

Gold production of the Porcupine region to date.

Year.

1898........................

1899........................

1900........................

1901................;.......

1902........................

1903.........................

Total.................

Value.

$1,000

9,000

50, 000

110, 000

140, 000

150, 000

$460, 000
14 THE PORCUPINE PLACER DISTRICT, ALASKA. [BULL. 236.

TOPOGRAPHY.

MOUNTAINS.

The mountains of the Porcupine district are an eastern wing- of the 

lofty St. Elias Kange. Viewing the region from one of the summits 

the general aspect is that of a high plateau dissected by numerous deep 

and narrow valleys. The surrounding peaks are rugged and precipitous, from 5,000 to 7,500 feet.in elevation, below which glaciers and 

fields of snow fill the uppermost parts of the valley's and canyons. 

The mountain slopes, which rise gradually, with no abrupt benches 

or terraces, have all been rounded by moving ice, and there is evidence to show that all but the highest peaks were once buried beneath 

a continuous field of ice and snow.

DRAINAGE.

Of the many rivers entering Lynn Canal the Chilkat is the largest, 

draining, with it tributaries, the county within 60 miles of its mouth at 

Chilkat Jnlet. Most of its waters come from melting glaciers and snow 

fields. Near its head it runs through a canj^on-like valley extending 

down to the mouth of Bear Creek, a western tributary, but from this 

point flows in many channels over a broad gravel flat. It has built a 

delta 2 miles wide at its mouth and is slowly filling up the head of the 

inlet. The eastern slope of its lower basin is very abrupt and is characterized by rounded peaks of intrusive rocks, averaging 5,500 feet in 

elevation, while to the west the bank rises to a densely wooded ridge 

of 1,500 feet elevation, composed mainly of slate, back of Avhich are 

high, snow-covered mountains.

The most important tributaries of Chilkat River are the Klehini, 

the Salmon (Tsirku), and the Takhin, named in order of size. The first 

named is a rapid river, averaging 100 feet in width and rarely exceeding 5 feet in depth. Eighteen miles from its mouth it, like the Chilkat, 

changes from a gravel filled valley a quarter of a mile or more in 

width to a comparatively narrow, steep-sided canyon. Its waters are 

seldom confined to one stream, but are divided by many gravel bars 

into a network of interlacing channels. Its main channel is continually shifting, rendering canoeing or sailing up the river difficult 

to the inexperienced navigator. Many of the smaller streams, flowing at right angles to the river, are glacier-fed mountain torrents, 

too steep and rapid for canoes, and often impossible to ford during 

high water, even near their sources.

At the mouth of Porcupine Creek is a gravel deposit extending 1 

mile to the westward and lying from 60 to 80 feet above the river bed; 

this deposit probably represents a former delta of the creek, having 

been built up when the river was at that height. On this terrace the 

town of Porcupine has been built.
U. S. GEOLOGICAL SURVEY ULLETIN NO. 236 PL. IV

A. PORCUPINE CREEK AT NO. 1 ABOVE DISCOVERY CLAIM.

;;. .._.._ OF PORCUPINE CREEK. 

Looking south.
WKIGHT.] TOPOGRAPHY AND GEOLOGY. 15

Chilkat Lake, at the .mouth of Salmon River, and two other lakes 

which fill basins at elevations of 1,200 and 800 feet in the hills just east 

of Porcupine, are probably the result of damming, either by glacial 

moraines or by alluvial gravels. 

The accompanying map (PL II), giving the main watercourses and 

their tributaries, is taken for the most part from the unpublished map 

made by the Boundary Survey Commission in 1892, though a few necessary corrections have been made as accurately as possible from foot 

traverses and topographic sketches.

GEOLOGY.

INTRODUCTION.

The geologic reconnaissance of southeastern Alaska" has led to the 

recognition of certain fairly well-defined belts of rocks extending'

parallel to the coast line, which have a striking lithologic uniformity 

along the extension of their strike. The great igneous complex which 

'forms the country rock of the Coast Range is the best defined of these 

belts, stretching from British Columbia -throughout southeastern 

Alaska. While the dominating rock of this mass is of a granitic 

appearance, and was so designated by Dawson 6 and others, microscopic 

studies have shown it to be more closely related to dioritic rocks. 

West of this Coast Range igneous belt are found metamorphic rocks 

of various types which will probably eventually be differentiated into 

a number of formations. The age of these metamorphic terranes is 

not definitely determined, but probably falls largely in the Paleozoic.

The area under discussion contains both sedimentary beds, usually 

considerably metamorphosed and probably falling into the abovedescribed zone of altered elastics, and igneous intrusives of the Coast 

Range zone.

The general distribution of the sedimentary and intrusive rocks of 

this region is shown on the accompanying geologic map (PI. V). The 

Porcupine district lies a few miles southwest of the Coast Range dioritic belt, which is here about 80 miles across. Adjacent to this on the 

south is a zone, 8 miles wide, occupied principally by metamorphic 

black slates, phyllites, and limestones, with strongly developed cleavage parallel to. the general northwest-southeast trend of the diorite 

contact, this being also the general direction of Klehini Valley. This 

sedimentary series is limited on the south by an outlying band of diorite from 2 to 4 miles in width, also striking northwest and southeast. 

This diorite band narrows toward the southeast, extending in this direca Brooks, Alfred H., Preliminary report on the Ketchikan mining district, Alaska: Prof. Paper U. S. 

Geol. Survey No. 1,1902. Spencer, Arthur C., The Juneau gold belt: Bull. U. S. Geol. Survey No. 226, 

1904, pp. 28-43.

l> Dawson, G. M., Report.on an exploration in the Yukon district and northern British Columbia; 

Ninth Ann. Kept. Geol Survey Canada, vol. 3, pt. 1,1888, p. 128,
16 THE PORCUPINE PLACER DISTRICT, ALASKA. [BULL. 236.

tion only to Salmon River, where it disappears. Porcupine and other 

gold-bearing creeks of this district lie mainly in the sedimentary rocks, 

though their upper portions cut into the diorite band to the south. 

This band has been the source of the large bowlders contained in the 

creek wash (PI. VI).

SEDIMENTARIES.

The sedimentary rocks, as before stated, consist of a series of slates 

with interbedded limestone. The slates are mostly black; some of 

them soft and rich in graphite, others hard and flinty, while adjacent 

to the limestone beds they are usually more or less calcareous. The 

limestones are sometimes fossil bearing, but as a rule they show evidence of considerable dynamic action, which has contorted and pressed 

the shells so that it is difficult to recognize their original form. The 

general strike of the sedimentaries is N. 60° W., dipping 75° NE., 

though this varies greatly. The beds are often wrinkled and folded, 

but apparently on a small scale, as no repetition of groups of strata 

was observed. The diorite contact usually follows the stratification,- 

though in some places the intrusive masses crosscut the slates. Next 

to the diorite the slate has been baked and altered to a flinty hornstone for a width of several hundred feet. Similarly the limestone 

beds' have also suffered alteration to white fine-grained crystalline 

marble. A good example of this is shown just back of Pleasant Camp 

(See map, PI. V).

A small collection of fossils gathered from a stratum of limestone 

on Porcupine Creek were determined to be of lower Carboniferous 

age by Dr. G. H. Girty, of the United States Geological Survey. The 

following is an abstract from his report:

The forms identified are:

Crinoiclal fragments. Spirifer striatus.

Productus latissimus. Camarophoria ? sp.

Productus seniireticulatus.

The age is clearly Carboniferous, and though I hesitate to offer a further opinion 

upon a fauna which is more or less strange, I believe that it is of lower Carboniferous 

age. The faunal type, however, is that of the lower Carboniferous of the west coast, 

and not that of the Mississippi Valley and Eastern States. I believe that it is to be 

correlated with the later portion of the lower Carboniferous of the Mississippi Valley, 

or even that it is somewhat .younger. Lower Carboniferous horizons have already 

been reported from Alaska, but the present fauna is not precisely the same as any 

of those so far discovered.

In a report on the Ketchikan mining district Mr. Brooks a calls attention to a coral found in the debris of Dirt Glacier of Glacier Bay, 

which was determined by Mr. Schuchert as belonging to the Carboniferous age. This district, however, is 40 miles south of Porcu-

«Brooks, Alfred H., Preliminary report on the Ketchikau mining district, Alaska: Prof. Paper, 

U. S. Geol. Survey No. 1,1902.
U.S.GEOLOCIGAL SURVEY BULLETIN NO. 236 PL. V

ECONOMIC GEOLOGY OF THE VICINITY OF PORCUPINE

From Internatimial Boundary Commission. BY CHARLES W. 

LEGEN D

Gravels producing 

placer gold

Gravel deposits

known to be gold

bearing

Gravels believed not

to be of economic

importance

Mineralized areas 

as far as determined

Shales and limestones

Scale

O 1 2 3

Contour interval 1000 feet 

1904-
WBIOHT.] . GEOLOGY. . 17

pine, and as the intervening rocks are unknown, a correlation of the 

sedimentary formations in the two areas is hardly advisable without 

more thorough investigation.

INTRUSIVES.

The rock of the" Coast Range intrusive belt in this region is mainly a 

coarse-grained diorite of a light-gray color, composed of plagioclase 

feldspar, hornblende, some biotite, and a little quartz, though specimens collected from different places vary in composition. The main 

mass north of Klehini River corresponds with the description above. 

The narrow belt at the head of Porcupine Creek contains more biotite, 

and segregations of hornblende and mica are often prominent, causing 

large dark spots, which are locally characteristic. The continuation 

of this belt to the east at Cotton wood Creek is characterized by a 

microcline feldspar and a larger amount of quartz. Under the microscope some of the minerals are seen to have been crushed, indicating 

that since the intrusion of the diorite they have been subjected to 

pressure and movement. This diorite rock is locally termed granite, 

which it resembles veiy closely and from which it can be distinguished 

only by careful examination.

In the central part of the sedimentary series there are several crosscutting greenstone dikes, averaging 10 feet in width and often traceable for several hundred feet. They are green in color, fine grained, 

often porphyritic, and under the microscope were determined to be 

altered diabase, occasionally mineralized. The relative ages of the 

diabase and the diorite could not be determined, as the two were not 

found in contact.

On the north bank,of the Klehini, seemingly interbedded in the 

slate, there is a greenstone schist forming a bed about 40 feet wide. 

Aside from this no schists were observed in the district.

MINERAL OCCURRENCE.

The sedimentary rocks have all been more or less mineralized by 

stringers and veins of quartz and calcite, but an especially noteworthy 

impregnation of iron sulphides forms an interrupted zone of mineralization in the southern portion of the sedimentary series. The sulphides in the slates occur as films or frequently as lenticular masses a 

few inches in width, parallel with the bedding. Two samples of the 

mineralized slates, one an average across.several feet and the other 

from a rich seam, gave respectively $0.41 and $2.48 per ton in gold. 

Samples from near the mouth of the Porcupine, where the slates ; afe 

apparently unmineralized, taken by Mr. Brooks during his short visit 

to this region in 1899, a gave traces of both gold and silver.

"Brooks, Alfred H., op. cit., p. 374. 

Bull. 236 04 2 -..' -.;«
18 THE POECUPINE PLACEE DISTEICT, ALASKA. [BULL. 236.

The quartz veins are not very abundant, and as a rule are short and 

small, often merely stringers parallel with the structure of the slates. 

A few which cut directly across the formation carry galena and sphalerite, with a small amount of chalcopyrite, and, though quite narrow, 

often persist for considerable distances. Calcite veins, which are 

more numerous than those of quartz, are usually a foot or more in 

width, and are often weathered to a light-brown color on the surface, 

while of a bluish color and fine granular structure when freshly 

broken. They often carry cubes of pyrite, which occasional^ measure an inch across. From veins of this nature up McKinley Creek 

some native gold has been reported.

Besides the small veins a quartz ledge 100 feet wide outcrops at an 

elevation of 2,000 feet on the ridge south of Porcupine. Although 

apparently quite barren, a small sample from this gave an assa}^ value 

of $5.28 in gold. A similar ledge occurs across the Klehini at 1,500 

feet elevation, on the ridge west of Bowlder Creek. About 2 miles 

below Porcupine is a third mineralized deposit rich in sulphides, 

with calcite as gangue mineral, but a sample taken here gave an assay 

value of only 41 cents. These different ledges have all been located and 

relocated, and on some assessment work has been done, but none have 

been developed, owing to transportation difficulties.

GLACIATION.

/

Evidence of general glaciation was found over the greater part 

of the area explored. Observations show that the entire district 

was formerly covered by a field of ice similar to that now existing to 

the north of Muir Glacier, with only the highest, most rugged peaks 

protruding. The greatest altitude at which the action of ice was 

observed was 4,500 feet, on Granite Mountain just west of Bowlder 

Creek. .

The main dissection of the country is attributed to water erosion 

previous to the Glacial epoch, but many of the topographic features, 

such as rounded ridges and wide U-shaped valleys, are attributable to 

the action.of ic'e. Of especial interest are the high gravel-filled channels on the mountain slopes several hundred feet above the present 

creeks. These channels have probably been formed by a field of 

moving ice, which cut troughs into the bed rock along the trend of 

the softer interbedded slate strata. During the retreat of the ice from 

the valleys gravels were deposited in these channels, which, owing to 

later, erosion of the creek bottoms, have been left at high elevations 

on.the ivalley slopes. At about 200 feet; elevation above the present 

creek, on,the south bank of the McKinley, a deposit in one.of these 

channels is being hydraulicked. This is crossed by the present creek 

canyon, exposing a good section of the gravel bed (PI. VI, B}.

The concentration of gold in the placers has no doubt been going on 

in the different streams ever since their lower valleys were vacated by
U. S. GEOLOGICAL SURVFY

A. BENCH DEPOSIT ON CRANSTON CLAIM

11. HIGH-
WEIGHT.] ECONOMIC GEOLOGY. 19

streams of ice. Previous to melting, the glaciers were mainly eroding, 

and few, if any, local deposits could have been formed until they 

began to retreat. As they gradually disappeared, the materials which 

thvy ground off from the bed rock, with other debris furnished by 

tributary streams, have been concentrated in the creek beds by the 

sorting action of flowing water, thus forming valuable placers.

ECONOMIC GEOLOGY.

DISTRIBUTION OF AURIFEROUS GRAVELS.

The geologic map (PL V) shows the distribution of the goldbearing gravels. It will be observed that the deposits actually producing gold are confined to the creeks which crosscut the areas of 

mineralized slates, and that neighboring valleys contain no valuable 

amounts of gold. The auriferous gravels on the Porcupine extend to

the junction of McKinle}r Creek and up this tributary for a distance of 

1 mile. Gold is limited to the lower claims on Nugget Creek, and a 

similar occurrence may be expected on Glacier Creek, though this has 

not been sufficiently prospected to determine the local distribution. 

The gravels of the tributaries entering Klehini River from the north 

are believed to be of no economic importance.

CLASSIFICATION OF PLACERS.

There are three types of gravel deposit in the Porcupine basin 

creek gravels, side benches, and high benches. The creek gravels fill 

the present channel to various depths and can not be definitely separated from the side benches or gravel banks which rise in places 20 

and 30 feet above the stream. The high gravels occupy portions of 

former channels which in some places have been preserved and in 

others have been cut out by the downward erosion of the streams.

The first of these side-bench deposits, at No. 2 below Discovery, is 

an extensive gravel bed on the east side, 25 feet above the creek. 

Rich gravels occur at high benches 80 feet above the creek on the first 

three claims above Discovery, and a similar deposit has been found 

on the'south bank of Mc.Kinley Creek, three-quarters of a mile from 

its mouth, at an elevation of 200 feet. Of the above types the creek 

gravels, as those found on Discovery claim and those near the mouth 

of McKinley Creek, are of greatest value. . 

CHARACTER OF GRAVEL.

The stream and bench gravels consist mainly of a fine -wash containing worn slabs and fragments of slate, and rounded bowlders often 2 

or 3 feet in diameter, mostly of diorite, with some greenstone. In the 

upper portions of the creeks the gravel wash becomes coarser and 

more angular. There are no materials in the gravels which could not 

have been derived from the drainage basin in which they occur.
20 THE POECUPINE PLACEE DISTRICT, ALASKA. [BULL. 236. 

ASSAYS OF SAMPLES.

Hardly enough material was taken to assure reliable commercial 

tests, but the presence of gold in all the samples indicates the advisability of careful prospecting for lode deposits. The' following list 

gives the assay values of several samples from quartz ledges, mineralized slates, etc., in the vicinity of Porcupine:

Assay of mineralized quartz, slate, etc., from Porcupine district.

No.

1

2

3

4

5

6

7

Gold. .

Oz. per ton.

0. 12

.02

 .26

.'06

' .02

1. 10

266. 60

Silv.er.

Oz. per 'ton.

0.08

Trace.

Trace.

.08

None.

.08

68.32

Value.

Per ion.

' $2. 48

 41

5.37

' 1:28

 - .41

' 22; 78

5, 544. 20

 Locality.

Mineralized slate, Porcupine Creek.

Mineralized slate 1 mile north of Pleasant Camp.

Large quartz. ledge on ridge back of Porcupine.

Large quartz ledge on north bank of Klehini 

River.

Prospect 2 miles east of Porcupine.

Glacial mud, Cranston claim; sample taken 

at random.

Black sand concentrate, from sluice boxes,- 

Nugget Creek. .

Though a large amount of black sand has been thrown away in the 

past, its value is now generally recognized. The test given merely 

emphasizes the wastefulness of the rough methods of mining which 

have been employed. The sample marked "glacial mud, Cranston 

claim," was taken from a layer of rock flour and small pebbles, several 

feet thick, occurring between two beds of gravel. Too much importance, however, .must not be placed upon the -high assay of this material, 

which was taken at haphazard, but it suggests.that careful tests of the 

so-called glacial muds should be made.

SOURCE OF PLACER GOLD.

The gold from.Porcupine basin is well worn and flattened, occurring 

in flakes or small nuggets, and is but rarely rough and irregular. Its" 

assay values are-reported 'to vaiy from $16.80 on McKinley Creek to 

$17.20 on the lower portion of Porcupine Creek. It is of a bright 

yellow color, though some, of the tiner gold on the lower claims has a 

dull bronzy appearance. Nuggets of an ounce weight are not unusual, 

and one piece is reported weighing 8 ounces. '

It is generally-believed by :the discoverers and operators that the 

gold of Porcupine and Nugget creeks has been brought from some distant source;- The supposed necessity of this view is urged from the 

coarseness and worn condition of the nuggets, and :from the absence of 

coarse.g.old^andof more^than"small amounts of free metal in any of the 

local veins. The importance of these facts can not be overlooked in
u. R. GEOLOGICAL SURVEY

A. LARGE FLUME, DISCOVERY CLAIM.

E BUC
WMGHT.] ECONOMIC GEOLOGY. 21

attempting to determine the origin of the gold, but it is difficult to 

show the possibility of any 

outside origin, because the 

deposits are so limited in 

extent. If the gravels, with 

their gold contents, had been 

brought into these creeks by 

glaciers, there would be no 

reason for the observed concentration in one stream and 

the absence of gold in adjacent gulches. This and the 

fact that pay gravels are not 

found in the upper portions

of the gold-bearing creeks

above the mineralized slates, 

nor in the diorite belt, 

strongly suggests that the 

gold has been derived from 

the surrounding country 

rock.

The problem is quite similar to that presented by the 

auriferous gravels of the 

interior and of Seward Peninsula, where the local source 

of the gold concentrated in 

the placers is usually accepted.

Natural washing 'and reconcentration of the auriferous bench deposits by small 

tributary streams has contributed a large amount of 

gold to the gulch gravels. 

This explains the occurrence 

of rich deposits in potholes 

and the irregular distribution of gold in the gravel 

beds.

DEVELOPMENTS.

After the rush to Porcupine Creek in 1898-99 but 

little development was undertaken until 1900, when several claim

FIG. 1. Map of Porcupine Creek, showing location of 

claims.
22 THE PORCUPINE PLACER DISTRICT, ALASKA. [BUM, 236.

holders bonded or leased their properties, while others formed companies in order to operate on a.large scale. The conditions to be met 

require a still further combination'of interests for economic exploitation, and negotiations are now being made to bring the entire creek 

under a single management.

The extensive gravel bed of Klehini River is known to contain 

some gold, though no comprehensive tests have been made to show its 

probable value. Dredging would seem to be the only practicable 

method of mining this deep deposit.

In describing the placer properties those at the mouth have been 

first considered, while the claims following are referred to in regular 

order (PL VII).

DESCRIPTION OF CLAIMS. 

. .PORCUPINE CREEK.

Delta claims. On the western bank of the Porcupine, near its mouth, 

the gravel bench formed. by the old delta was formerly all staked, 

though at present only the claims neighboring the creek are held, 

and on these no more than the required assessment work has been 

done. The depth of the-deposit is unknown and the few test pits on 

the several claims are said to have given only low values.

Cranston claim. This claim, the first on the creek under development, is 1 mile from the mouth of the Porcupine. The gravel bed is 

40 feet in depth, the top of the deposit forming a bench on the east 

side 20 feet above the stream. The gravels are said to carry good 

values, but the gold is not uniformly distributed. Next to bed rock 

is a layer 2 to 3. feet deep carrying high values in gold, though this is 

sometimes cut off by ridges in the bottom of the channel. Overlying 

this is a 15-foot bqd less rich in values, containing many quartz pebbles and some bluish clay. The next 2 feet are of clay and small 

gravel wash, probably, of glacial origin. Though this material was 

supposed to be quite barren a sample submitted to fire assay gave a 

value of over $20 per ton, showing this stratum to be worthy of closer 

examination. Above the clay there is 15 to 20 feet of j^ellow gravel, 

averaging 150 feet in width and carrying good values (fig. 2).

Besides gold, platinum is said to occur in the black sands, but a laboratory test did not verify the report. Galena, magnetite, chalcopyrite, some arsenopjTite, and a large amount of pyrite occur in the 

concentrates.

To develop this property a flume 1,200 feet in length was built 

along the creek bank, supplying the hydraulic hose used to work the 

gravels and furnishing power for the bucket elevator, centrifugal 

pump, and sawmill. A 6-horsepower derrick, receiving power from 

a steam engine, has been installed to hoist bowlders too large for the
U. S. GEOLOGICAL SURVEY 

A. CLAIM NO. 1 ABOVE DiSCOVERY. B
WHIGHT.] DESCRIPTION OF CLAIMS. 23

bucket elevator. . At the lower end of the claim a pit has been sunk 

and into this the gravels are washed, going first through a narrow 

sluice box, which gathers the coarse gold, and then into a sump cut 

in the bed rock. From this sump the bucket elevator lifts the gravel 

to the recovery sluice boxes on the surface (PI. VI, A).

An old creek channel 65 feet.above the Porcupine, at the upper end 

of the claim, was formerly worked, and $3,000 is said to have been 

recovered, though the greater part of its gravels remain unworked, 

owing to the difficulty in getting water to that elevation. The development of this claim has been done by lessors, who expect large 

returns the coming season (1904).

On the next claim above, in 1901, a pit 20 feet deep was sunk which 

exposed 80 square feet of limestone bed rock; $10,000 is said to have 

been taken out. During a period of high water the excavations were 

filled in, and the property has not been worked since.

Discovery claim. The bed rock, which here crosses the creek diagonally, striking N. 60° W., consists of alternate beds of flinty and

SateW 

:ll Ihl Illllllllll III I I I I III Illl i'l 11

FIG. 2. Section across Cranston claim, showing side-bench deposit.

graphitic slate, in which natural troughs have been formed. The gold 

has been concentrated in these natural riffles, and often nuggets have 

worked down into the softer slate for 2 or 3 feet. The creek gravels 

on this claim average 12 feet in depth, with no definite layers, excepting that most of the pay dirt lies on bed rock. Gold was first discovered in a small gravel bench 30 feet above the creek on the west bank; 

$15,000 was taken out with shovel and sluice box from an area 10 by 

30 feet.

The stream has been diverted into a flume 20 feet wide, 5 feet deep, 

and 1,400 feet long, with a 3i per cent grade; through this the 

water rushes at a rate of from 3,000 to 5,000 miner's inches per 

minute. About 100 feet above the outlet of the flume a pit has been 

sunk and a sump 10 feet deep excavated in bed rock. All the gravels 

are worked down through a short sluice box, which saves the large 

nuggets, into this sump, and are then lifted by a bucket elevator, of 

4,000 cubic yards capacity per twenty-four hours, to the surface sluice 

boxes. A water wheel receiving power from a small flume drives the
24 THE PORCUPINE PLACER DISTRICT, ALASKA. [BULL. 236.

elevator, pump, derrick, and a sawmill. It is planned to continue 

the pit upstream until-sufficient grade is se'cured for .ground sluicing. 

When the stream is confined the. current will''doubtless be able to carry 

off the tailings-(PL VII). "-' . .

Mix claim. On this property work is being done on a gravel bench 

from"20 to SO feet wide and 8 feet deep, occurring on both sides of 

the creek about 60 feet above the t stream. The valley widens at the 

lower part of the claim, and a broad bed of creek gravels has been 

deposited (PL VIII, A)'. The claim was leased by a mining company 

during the summer of 1901, but the operations did not prove successful and no further developments have been undertaken. At present 

part of - the :u'pper bench is leased-to a miner, who has, recovered, many 

nuggets of gold. ' . ::.. . .;

 Finley - claim. The deposit here -is on the same bench as the one 

below. The gravel bed is 100 feet wide, 6 to 10 feet deep, and 80 feet 

above .the creek. In 1901 a large production was reported from this 

property, but it is riot- operated at -present- (PL VIII,- B; fig. 3).

('11,11111 ii iiii ii ii iiiiiiii/iii/iiiiiiiiiiih

PIG. 3. Section of Porcupine Creek at the Finley claim.

On the Legal Tender fraction,-an extension.of the "Finley bench, a 

good section of the channel with the gravel .deposit is exposed. .One 

man working with a 6-foot sluice box was making good wages.

Following-this is the Wiley claim, which corresponds in character 

to the'.Finley claim; no development work has been done on the 

bench ?it this place.

M'KINLEY CREEK. .

. At-the-junction of McKiriley and Porcupine creeks the first location 

is the Lewis claim, joining the AViley .property arid extending 800 feet 

along the Porcupine to the forks, thence 500 feet up McKinley Creek. 

A hundred paces above the forks there is a waterfall about >60 feet 

high, known as the McKinley-Falls, below which good values have 

been-found. . - , .

Chisliolin claim. The, next claims in succession are the Chisholm 

and Hall properties, owned by the United. Gold "Mining Company. 

On -the former of these, where the. placer-deposit is being exten-
U. fi. GEOLOGICAL SURVEY

A. CHISHOLM CLAIM, McKINLEY CREEK.

It. Mc
 WRIOHT.] DESCRIPTION OF CLAIMS. 25

sively developed, a good example of ground sluicing may be seen 

(PI. IX, J3.} The stream is diverted into a 600-foot flume built along one 

side of the creek, and the large bowlders from the bed are piled along 

the banks or are used to form a narrow channel in which to confine 

the stream and increase its velocity. Through this the water is turned 

from time to time and its rapid current carries much of the gravel 

downstream. Thus the surface gravels are gradually removed and the 

gold is concentrated in a shallow deposit on bed rock, from which it 

is easily recovered. Very good returns are expected from this claim 

at the end of the season when bed rock is cleaned up. A small sawmill is the only machinery used on the property.

Woodin claim. The Woodin claim and several others are owned by 

the McKinley Creek Mining Company. The first work on this property was on the creek bed, but in 1903 all operations were confined to

a high bench deposit on the south side of the valley, 200 feet above

the creek bed. The gravels fill two parallel channels, one 15 feet deep 

and 40 feet wide, the other 30 feet deep and 30 feet wide. In the

Gravel

FIG. 4. Section of McKinley Creek at the Woodin claim.

deeper of the two a good section of the gravel deposit is snown (fig. 4; 

PI. VI, J5). Next to bed rock there is gravel wash, consisting of diorite 

cobbles and slate fragments, which contains good gold values. Overlying this there is a deposit of blue clay or rock Hour some 3 feet 

deep, carrying logs and branches of trees, and regarded so valueless. 

Above the clay are several feet of coarse wash, capped by a bed of 

gravel cement 2 to 3 feet thick. This cemented gravel or hardpan can 

not be disintegrated by the hydraulic stream, and is*even difficult to 

loosen with jammer and pick. The gold is coarse, not so much worn 

as that of the Porcupine, and somewhat higher in silver values.

The property borders an area of mineralized slates, containing many 

calcite veins, with some crosscutting quartz veins, all of which are 

heavily charged with pyrite. A sample of the well-mineralized slate 

gave $2.4:8 in gold per ton. To develop this property sluice boxes 

have been placed along the bottom of the channel, and through these 

the gravels are washed b}7" a hydraulic giant, capable of working
26 THE PORCUPINE PLACER DISTRICT, ALASKA. [BOLL. 236.

down the bench deposit within a radius of 200 feet. A ditch leads 

the water from the upper part of Cahoon Creek to a penstock 400 

feet above the workings, from which a pipe line supplies the giant 

and furnishes power for an overhead trolley, which carries the large 

bowlders to a dump at the lower end of the claim (PI. X, B}.

Other claims. Higher up on the south slope of the McKinle}^ 

other bench deposits have been investigated, but nothing of importance has been reported. The creek deposits above Woodin claim have 

not been developed sufficiently to prove their value, though, some 

unsuccessful attempts were made to work claims on Cahoon Creek 

(PI. X, A). It is claimed by some of the prospectors that there is no 

pay on the Porcupine above the forks, nor beyond the mouth of Cahoon 

Creek on the McKinley.

NUGGET CREEK PLACERS.

Nugget Creek camp may be reached either by going up Salmon River 

some 20 niiles, or by way of Porcupine, over the divide at the head 

of McKinley Creek. This creek rises in the same ice field which 

feeds McKinley Creek, and flows through a narrow canyon-like valle}r 

for a distance of 2^ miles into Salmon River. Like nearly all the 

tributaries of- Salmon River, few of which are more than 2 or 3 miles 

in length, it enters from the north.

Creek gravels. The gravels of the present creek bed and the low 

side benches form the principal deposits in Nugget Creek. The 

former occur as rich pockets, filling the small glacier-scooped basins, 

commonly called potholes. The low bench deposits are usually very 

narrow and show more or less well-defined beds, a section through 

which would be as follows:. On bed rock a 2-foot layer of glacial mud; 

above this a foot or more of cemented slate wash; then a 10-foot bed

of pay dirt, consisting of large and small gravel wash; and capping 

this a few feet of rock slide and surface dirt. Many large angular 

blocks of diorite, several feet in diameter, occur in these creek gravels, 

adding greatly to the cost of mining.

Seven claims have been staked on these creek deposits, two below 

and four above Discovery; the latter, however, is the outy one which 

has been developed. To work the gravels on this claim the stream 

has been diverted into a flume, freeing the creek bottom and furnishing power for a derrick of considerable capacity, which handles the 

large diorite bowlders. A pipe line, fed from an upper flume, supplies 

water under a 200-foot head to the hydraulic plant by which the gravel 

banks are worked down through long sluice boxes 2 feet wide resting 

on bed rock. During the two years of development encouraging 

results are reported, and it is believed that future exploitation will 

yield large returns.
U. S. GEOLOGICAL SURVEY ULLETIN NO. 236 PL. X

A. HYDRAULICKING AT HEAD OF CAHOON CREEK.

E. HYDRAULICKING BENCH DEPOSIT ON WOODIN CLAIM,
RAINY HOLLOW DISTRICT. 27

Bench deposits. No extensive deposits have been found in the 

tributary creeks, but along Salmon River between Nugget and Cottonwood creeks is a bench deposit, probably marking a former river level, 

which has an average width of 1,500 feet and is from 20 to 40 feet 

above the present river. The greater part of the bench has been 

located, and plans are being made to work it by drifts and raises, 

using underground sluices supplied with water from Nugget Creek.

Near Nugget Creek the bed of Salmon River, over which the river 

flows in many channels, is a mile in width. Colors of gold may be 

obtained along this gravel deposit from a point a mile below Nugget 

Creek to above Cottonwood Creek. Fifty or more claims were staked 

last summer (1903) on these river bars, and an attempt will be made next 

season to work parts of the extensive deposit by dredges.

RAINY HOLLOW DISTRICT.

It was no part of the purpose of the present investigation to study 

the copper deposits of Rainy Hollow, but as opportunity was offered 

a brief visit was made to this, district, which has since been included 

in British Columbia by the newly established boundary line. 

- Rainy Hollow is the name given to the basin at the head of Klehini 

River, where the onty lode prospecting in the Chilkat drainage has 

been done. The ores are copper and silver, very little gold having 

been found. The valley gradually ascendj to dome-shaped hills, 

covered on the lower levels with a luxuriant growth of small trees 

and plants, but on the uppier levels almost barren of vegetation. 

The country rock consists of very much disturbed black slates and 

limestones, crosscut by greenstone and porphyry dikes.

There are several well-defined ledges, striking mainVy north and south. 

Those investigated were nearly vertical contact leads, lying between a 

limestone and an intrusive greenstone. They were composed chiefly of 

pyrrhotite, chalcopyrite, galena, and sphalerite, with quartz as gangue 

mineral. The Custer ledge, averaging 3 feet in width, can be followed for 2 miles over the mountain ridge; and the parallel Hartford ledge, separated from it by a greenstone dike 80 feet wide, 

may be traced nearly as far, although it is much more broken and 

faulted. The present surface ores are the richer sulphides of copper. 

No iron capping occurs over the veins, and oxides and carbonates of 

copper are not often found, and where observed are mere films, obviously due to surface weathering.

About 2 miles west of the Custer and Hartford ledges are some 

others less well defined and little developed. They are, however, 

richer in copper and silver, and are reported to be of greater value 

than either of the first mentioned, which can be of no economic value 

until transportation facilities are greatly bettered.
28 THE PORCUPINE PLACER DISTRICT, ALASKA. [BULL. 236.

The first locations here were made in September of 1898 by Joe 

Chisholm. During the following spring and summer a number of 

prospectors came into this region and located all the surrounding hillsides, without discrimination. Many have been abandoned and the 

properties still owned represent only a few of the original number. 

Several tunnels of various lengths have been driven on the Ouster 

ledge, which prove it to be very persistent in depth, as the outcrops 

show it is along the strike.

A detailed description of the claims staked in 1899 is given in the 

annual report of the Minister of Mines of Canada for 1900. The 

following assay is quoted from his report: "A general sample over 

3 feet of the Custer ledge gave an assay of gold 50 cents, silver 2 

ounces, copper 1.2 per cent, lead 3 per cent, zinc 5.5 per cent."

METHODS OF MHSTI^G.

On Porcupine Creek one finds the primitive methods of recovering 

gold ordinarily employed in partly developed placer districts. The 

miners have been obliged to make much out of little. With implements such as picks, shovels, whipsaws, and canvas hose, which they 

are able to carry to the place of working, they build ditches, flumes, 

and sluice boxes, and install small hydraulic plants. Under these conditions the richest deposits are sought out and worked, though frequently with little economy. When available pockets have been, 

exhausted work comes to a standstill, claim holders cease developing 

and do only annual assessment work, with the expectation of eventually selling out to companies who can consolidate interests and mine 

on an extensive and economical basis. During the last few years, 

however, several small sawmills have been erected by different parties, 

large flumes have been built, and hydraulic plants and bucket elevators installed; but equipments are still insufficient and no progress had 

been made toward consolidation up to the close of the season of 1903.

GROUND SLUICING.

As the best pay dirt is usually at the bottom of the creeks, it is 

necessary to remove the overlying gravel wash by some economical 

method. The stream must first be diverted into a flume built up on 

trestle work or running on one side of the creek. The creek bottom 

being freed from water, the large bowlders are piled along the banks 

of the stream, those too heav}r to move being broken b}^ sledge hammers and powder. A narrow channel built up of bowlders is thus 

formed, which serves to confine the stream and increase its velocity, so 

that on being turned back into the creek bed it is able to can\y off 

material which it could not otherwise have moved. The miners often 

enter this swift-flowing stream and by the use of shovels help the 

larger rocks downstream and off the claim. From time to time the
WBIGHT.] METHODS OF MINING. 2$

water is diverted into the flume, so that the large bowlders may be 

thrown out or broken up. Where the creek bed is wide this temporaiy channel, continually eating its way downward, must be moved, 

step by step, from one side of the creek to the other, then perhaps 

back again in case the gravels are deep. In this way the mass o'f 

gravel is disintegrated and washed away and the gold is concentrated 

in a shallow deposit on bed rock. To clean up the bed rock, sluices 

are laid, beginning at the lowest point on the claim, and into these the 

enriched gravels are worked by means of wing dams and shoveling. 

As the work progresses upstream additional boxes are supplied.

HYDRAULICKING.

In the upper channels, as at the Woodin claim, the gravels have been 

attacked where the present canyon crosses the former stream bed. 

The gravel at the rnouth was hydraulicked away and sluice boxes laid 

on bed rock, everything being worked into these sluice boxes by the 

powerful stream from the hydraulic nozzle. The large bowlders are 

transported to the mouth of the channel by a- trolley moving on a 

cable which extends the length of the workings (PI. X, j5).

MINING BY ELEVATORS. ' -

Where there is insufficient fall in the creek, or where deep potholes 

occur which necessitate a lifting of the gravel, bucket elevators are 

used. A pit is first sunk to bed rockj into which a sump is excavated, 

and in this the wash collects, to be elevated to the sluice boxes above. 

When sufficient space is cleared a small sluice box placed in the bottom of the pit collects most of the coarse gold (Pis. VI, VII).

SLUICE BOXES.

The boxes used in the pits are usually 12 feet in length, tapering 

from a width of 18 inches at the upper end to 14 inches at the lower 

end, thus allowing them to fit into one another. The larger sluice 

boxes used above surface are 2 to 3 feet wide and from 50 to 100 feet 

long.

Riffles of several sorts are in use. An ordinary form is made by 

fitting round blocks 4 inches thick, sawed from logs a foot or more in 

diameter, into the boxes. Another style consists of poles placed .a 

half inch apart lengthwise in the bottom of the sluice box.. Still a 

third sort is made of sawed strips of wood placed crosswise, and set at 

an angle with the bottom of the box, so as to overhang on the upstream 

side. It is customary to have two or three sets of the pole style at 

the head of the sluice,-and below these the block riffles. All of the 

riffles are held in place by wedges of wood, so that they can .be removed 

for the clean up, which begins with the uppermost set of riffles, the 

concentrates finally collecting on the lowest box.
30 THE PORCUPINE PLACEB DISTEICT, ALASKA. [BULL. 236.

WATER SUPPLY.

The flow of water in the different creeks varies with the seasons and 

also during the day. Most of it comes from glaciers arid snow fields, 

and on warm, sunny days it is usually one-third less in the morning 

than in the afternoon. The high-water season is usually in the middle 

of summer, not in the spring as might be expected on account of the 

melting of the snow. Low water is during the months' of May, June, 

October, and November. In the winter most of the creeks freeze 

over and are covered with snow, but a small stream continues to flow 

under the ice. Porcupine Creek has a flow varying from 2,000 to 

5,000 miner's inches per minute, and an average fall of 6 feet per hundred, or a total of 2,200 feet in the 7 miles of its course.

FORESTS.

The timber consists chiefly of hemlock, spruce, a few cedars, and 

occasional pines,, besides" an abundant growth of cottonwood on the 

river bottoms. The lower hills and mountain slopes are usually 

wooded to an elevation of 2,000 or 2,500 feet above sea level. During 

the winter months the sawmills are supplied with logs averaging not 

over 2 feet in diameter, mainly of spruce, and in early spring these 

are sawed and used for buildings, flumes, and sluice boxes. A dense 

undergrowth of weeds known as "devil's club," and of alders, covering 

the lower portion of the hills, hinders walking and makes prospecting difficult.

TRAILS AND TRANSPORTATION.

The usual route to the district formerly followed from Haines 

Mission was the Dalton trail, which has its starting point at Pyramid 

Harbor, on the West side of Chilkat Inlet, but this road is only practicable for travelers on horses, because of the difficult fords across 

Takhin and Salmon rivers. Another trail leads along the east bank 

of the Chilkat to Wells Post, where the Chilkat is crossed by canoe, 

and thence along the north bank of Klehini River to opposite Porcupine. This, generally known as Throp's trail, is used during the 

months of low water in the early spring and autumn. During the 

summer months it is best to wait for a favorable wind and sail upstream. Native canoemen are always available, and their services are 

necessary to those not familiar with the river.

Freight and supplies are usually moved in during the months pf 

winter and early spring, when the. snow and the frozen condition of 

the streams greatly facilitate transportation. In the summer Indians 

are hired to transport the freight in their canoes as far as Wells Post, 

from which it is carried on wagons by a fairly easy route along the 

banks of Klehini Eiver to Porcupine.
WEIGHT.] CLIMATE AND SUMMAEY. 31

CLIMATE.

No climatic records have been kept of the particular area under discussion. The inhabitants claim that the winters are more severe than 

in the parts of southeastern Alaska nearer to the open ocean and more 

directly influenced by the Japan Current. Heavy snowfalls begin late 

in October, and in places accumulations in the gulches do not disappear before the first part of June. The line of perpetual snow is 

about 5,000 feet above the sea, and many of the valleys have small 

glaciers at their heads. During the summer months, however, the 

climate is more pleasant than that prevailing along the coast, and the 

precipitation is considered to be less.

SUMMARY.

The gold-bearing gravels in this vicinity are confined to the few

creeks and benches within an area of 5 miles in width and 10 miles in 

length, extending from Nugget Creek on the Salmon to the mouth 

of Porcupine Creek on the Klehini. Belts of. mineralized slates 

included in this area are crosscut by the streams, and from these the 

gold has been derived. The workable deposits vary from 25 feet to 

several .hundred feet in width and are from a few feet to 40 feet or 

more in depth.

The gold-producing gravels on the Porcupine extend to the junction 

of McKinley Creek and up this tributary for a distance of 1 mile. On 

Nugget Creek the gold is limited to the lower claims.

The creek gravels are the most valuable; from information available they average several dollars to the cubic yard, though in local 

bonanzas much higher values are obtained. In the bench deposits 

lower values may be expected. The extensive river beds are known 

to contain some gold, but are of so low value that dredging would 

probably be the only profitable method of working them.

While some of the deposits on the lower claims of the Porcupine 

have been considerably developed, the greater number remain 

untouched, and to obtain the greatest yield from them it will be 

necessary to combine operations and work the various claims under 

one management by more economical methods than are at present 

employed.

INDEX,

Page. 

Acknowledgments, 1'ut of.................. 11

An way, C. H., discovery of gold by ........ 13

Army post, establisR.nent of............... 10

Assays, from Porcupine district, table of... 20 

Bear creek, claims staked on............... 13

' course of ............................... 13

difficulties on ....................:..... 13

gold of...........-..:".................... 13

rush to ................................. 13

Black sand, occurrence and value of ...... 20

Boundary, international, change of........ 11,12

Bowlder Creek, claims staked on .......... 12-13

course of ............................... 12

gold of...................................12-13

rush to ................................. 12-13

Brooks, A. H., cited on Alaskan rocks ..... 15

cited on Dirt Glacier fossil ............. 16

cited on Porcupine slates................ 17

examination of gold placers by........ 9

gold-bearing samples collected by ..... - 17

report by............................... 9

Gaboon, C. P., acknowledgments to........ 11

Cahoon Creek, mention of.................. 26

view on ................................ 20

Calcite veins, occurrence and character

of............................... 18

Carboniferous age, rocks of................ 10-17

Chilkat Lake, origin of..................... 15

Chilkat Peninsula, character of............ 10

examination of........................... 10

view of................................. 9

Chilkat River, drainage of................. 9

elevations on........................... 10,14

location of.............................. 9

rocks along............................. 10

source, course, and character of........ 14

trail by................................. 10

valley of................................ 10

Chisholra, Joe, location by................. 28

Chisholm claim, description of............. 24

view of................................. 24

Claims in Porcupine district, location of... 12 

in Porcupine district, map showing.... 21

Claims on Porcupine Creek, location and

development of................ 21-22

Clear Creek, mouth of...................... 13

Climate, character of....................... 31

Commission, International Boundary, survey by.......................... 9

Copper, occurrence of...................... 27

Bull. 236 04 3

Page.

Cottonwood Creek, discovery of gold on ... 13 

Cranston claim, description of............. 22-23

section across............................ 23

view of................................. 18

Custer ledge, assay of ore from............. 28

description of .......................... 27

Dalton trail, route of....................... 10, SO1

Dawson, G. M., cited on Alaskan geology.. 15- 

Delta claim, description of.................. 22

Developments in Porcupine district, extent

of......................... 21-27,28,31.

on Nugget Creek, extent of............ 20-27

on McKinley Creek, extent of.......... 24-26

on Porcupine Creek, extent of......... 22-24

on Salmon River, projection of......:.. 27

Dikes, greenstone, occurrence of........... 17

Diorite, occurrence and character of....... 15-17

Dirt Glacier, fossil from .................... 16

Discovery, claim No. 1 above, view of...... 22

claim No. 1 above, Porcupine River at,

view of......................... 14

Discovery claim, description of ............ 23-24

view of................................. 20

Drainage of Porcupine district, character of 14 

Elevations on Chilkat River, mention of... 10,14 

Elevators, use Of, in mining................ 29

view of................................. 20

Erosion in Porcupine district, character of. 18-19 

Explorations in Porcupine district, account

of............................... 9,12

Field work in Porcupine district, by C. W.

Wright, length.of............... 9

Fin-ley, , exploration by................ 12

Finley claim, description of................ 24

section at................................ 24

view of................................. 22

Flumes, construction of. See under claim, 

names,andundcr Developments, 

Forests, extent and character of............ 30

Fossils, in Porcupine district............... 10-17

on Dirt Glacier ......................... 16-17

Eraser, Doctor, acknowledgments to....... 11

Galena, occurrence of...................... 22

Geologic map of vicinity of Porcupine. See

Map, geologic .................. 1C

Geological Survey, exploration by.......... 9

Geology of Chilkat Peninsula,, character of. 10 

of Porcupine district, account of....... 15-19

Geology, economic, account of............. 19

Girty, G. H., fossils determined by. -....... 16

33
34 INDEX.

Page. 

Glacial mud, value of...................... 20

Glaciation in Porcupine district, evidences

of............................ 14,18-19

Glacier Creek, claims staked on ........... 12

rush to ................................. 12

transfer-of, to the United States........ 12

Gold, character of.......................... 20

concentration of .................... 1 !-19,21

discovery of, in Porcupine district..... 9,12

on Bowlder Creek .................. 12

on Porcupine Creek ................ J2

occurrence of........................... 20-27

output of ............................... 9,13

source of ............................... 20

Gold-bearing ores and gravels, assays of.... 20

Gold claims on Porcupine Creek, examination of, by A. H. Brooks............ 9

ciranite Mountain, glaciation on........... 18

Gravels, occurrence of...................... 18

Gravels, auriferous, classification of....... 19

distribution of.......................... 19

limits of................................ 31

location of, on Glacier Creek........... 19

on Klehini River ................... 22

on Nugget Creek ................... 19,26

on Porcupine River ................ 19

on Salmon River ....... '............ 27

on tributaries of the Klehini....... 19

Gravels, creek, character and location of.. 19 

value of................................ 31

Gravels, high bench, character and location of.......................... 19

view of................................... 22

Gravels, side bench, character and location of........................ I.. 19

value of ................................ 31

Grizzly Creek, claims staked on............ 12

Ground sluicing, example of........\...... 25

method of.............................. 28-29

view of................................. 24

Haines Mission, location of ................ 10

view of................................. 9

Hall claim, mention of..................... 24

Hanley, E. B., acknowledgments to ....... 11

Hartford ledge, description of.............. 27

History of Porcupine district............... 12-13

Hydraulicking, use of...................... 29

views of................................ 26

Igneous rocks, character of .......'......... ' 17

Intrusive rocks, character of............... 17

International Boundary Commission, survey by.......................... 9

Ka.tkwaltu, location of..................... 10

Ketchikan mining district, fossil from..... 16-17

A. H. Brooks cited on .................. 16

Klehini River, character of................ 14

gold of gravels of....................... 22

mouth of............................... 11

quartz ledge near ...................... 18

rocks on................................ 17

 trail by ................. 1............... 10

Klukwan, location of ...................... 10

population of........................... 11

Legal Tender fraction, description of...... 24

Lewis, Guy, acknowledgments to .......... 11

Limestone, occurrence of .................. 10

Page. 

Location of Porcupine district.............. 9

McClellan Flats, location of................ 10

McDonald, Captain, acknowledgments to.. 11 

McKinley Creek, claims and developments

on .............................. 24-26

claims staked on ............ .......... 12

' geologic section on..................... 25

gold-bearing calcite veins on........... 18

gold-bearing gravels on, Jimits of...... 31

gravels on.............................. 91

rush to.................................. 12

views on................................ 18,24

McKinley Creek Mining Company, property

of............................... 25-26

McKinley Falls, location of................ 24

Map of Porcupine district.................. 10

of Porcupine district, statement concerning. ........................ 9,15

Map, geologic, of vicinity of Porcupine .... 16

of vicinity of Porcupine, reference to .. 15,19 

Marble, occurrence of...................... 16

Marble Creek, claims staked on............ 12

rush to ................................. ri

Metamorphic belt, character and course of. 15 

Mineralization, zone of..................... 17

Mining in Porcupine district by elevators,

view of......................... 20

in Porcupine district, methods of ...... 28-29

Minister of mines of Canada, quoted on

Rainy Hollow district.......... 28

Mix, S. W., acknowledgments to ............ 11

exploration by ....................... 12

Mix claim, description of .................. 24

Modus vivendi, effect of.................... 12

Mountains in Porcupine district, character

and height of................... 14

Nugget Creek, dlaimsand developments on. 26 

course of ............................... 33

discovery of gold on.................... 13

gold-bearing gravels on, Jimits of...... 31

placers of............................... 11

trai Is to...'.............................. 26

source and course of ................... 26

O'Connor, J. M., acknowledgments to ..... 11

Paleozoic age, rocks of..................... 15

Peters, W. J., exploration under lead of.... 9

Placer gold. .See Gold.

Placers, classification of.................... 19

Platinum, reported occurrence of.......... 22

Pleasant Camp, marble near ............... 16

Porcupine, description of.................. 11

location of.............................. 11,14

population of........................... 11,12

view of................................. 12

Porcupine Creek, claims and developments

on .............................. 22-24

discovery of gold on.................... 12

flow of.................................. 30

geologic section on..................... 25

gold-bearing gravels on, limits of...... 31

gravel at mouth of ..................... 14

map of.................................. 21

mining on, methods of................. 28-29

quartz ledge near ....................... 18

views on................................ 14,18

Porcupine Creek basin, gravels of.. ...... 19
INDEX. 35

Page. 

Porcupine Creek placers, examination of,

by A. H. Brooks................ 9

study of ................................ 11

Prospectors, rush to Porcupine district by.. 12-13

21-22 

rush to Rainy Hollow district by....... 28

Quartz ledge, occurrence and character of. 18

Quartz veins, occurrence and character of. IS

Rainy Hollow district, assays of ores from.. 28

claims in ............................... 28

examination of......................... 27

location and character of............... 11,27

rush to.................................. 28

Rant, Captain, hospitality of............... 11

Reconnaissance by A. H. Brooks........... 9

Riffles, kinds of ..........'.................. 29

llipinski, Mount, view from................ 9

River beds, value of........................ 31

Routes to Porcupine region, account of.... 10,30

Salmon River, bench on.................... 27.

claims on............................... 27

discovery of gold on ................... 13

Schist, occurrence of....................... 17

Sedimentary belt, character and course of. 15 

fossiIs of................................ 16-17

gold-bearing creeks of.................. 16

Sedimentary rocks, mineralization of...... 17

Silver, occurrence of....................... 27

Page.

Silver-bearing ores and gravels, assays of.. 20 

Slates, mineralization of ................... 17

occurrence of...........................' 16

Slates, mineralized, source of gold in....20-21,31

Sluice boxes, size and character of......... 29

Snowfall, amount of........................ 31

Spencer, Dr. A. C., acknowledgments to...- 11 

cited on Alaskan rocks................. 15

Supplies, transportation of................. 30

Surveys in Porcupine district, mention of.. 9 

Throp's trail, use of........................ "30

Topography of Porcupine district, charac-

- ter of........................... 14-15

Trails. Sec Routes.

United Gold Mining Company, property of. 2-1-25

Water supply, amount of................... 30

Wells Post,location of...................... 31

Wiley, , exploration by................. 12

Wiley claim, mention of................... 24

Woodin claim, description of............... 25-26

geologic section at..................... 25

view below............................. 24

view of.................................. IS, 26

Wright, C. W., assignment to Porcupine region of.......................... 9

route followed by ...................... 10

Yeudestaka, location of.................... 10

o