130 ALASKAN MINERAL RESOURCES IN 1905. 
STRATIFIED ROCKS. 
The bed rock between Circle and Fort Hamlin is composed largely of slate, quartziti 
chert, conglomerate, limestone, sandstone, tuff, and diabase These have been grouped 1>\ 
Spurr into one formation, called the Rampart series// mid from fossils collected at various 
points are known to be of Devonian age. 
The slates are for the most pari black and seen only in patches of small chips along the 
ridges. Near the head of Willow Creek an outcrop of red and green slate was found, from 
which slabs nearly a foot square and an eighth of an inch thick could be procured. 
Quartzite is common throughout the entire area and varies from typical gray quartzhj 
with sugary fracture to cherty rock and to softer sandy beds. 
Chert is a dense, siliceous rock of various colors, including black, gray, red, and greea 
Red and green cherts were found near Twelvemile House on Birch Creek, and gray elicits in 
the Crazy Mountains and on Willow Creek were seen folded and even strongly contorted. 
Conglomerate in this region is composed mostly of chert pebbles. These vary from the 
size of buckshot to cobbles (i inches in diameter. Small bands of sandstone and slate are 
found interbedded with the conglomerate. This rock occurs most abundantly in the 
Crazy Mountain-. 
Limestones of two distinct type- are recognized here. ( )ne is while or gray, shows no dis- 
tinguishable bedding whether fresh or weathered, and occurs in conspicuous projecting ledge* 
The other is gray to blue on the outside, dark blue on the inside, ( hin bedded, and strews the 
ground with small flat slabs. Limestone of the former type occurs in narrow belts in the 
Cia/.\ Mountains. One belt not over KM) feet t luck could be recognized for several miles by 
its prominent outcrops. The White Mountains in (Ik 1 big bend of Beaver Creek, :i portion of 
the ridge between Beaver and Victoria creeks, and the mountains between Victoria Creek 
and Yukon flat-: are largely of white limestone. 
Sandstone and sandy shale constitute a small part of the format ion and seem to be more 
abundant west of Beaver Greek than easl of it. 
Near the head of Victoria and 1 less creeks, and close to the (lats north of the head of \ ic- 
toria Creek, -ofi black shales w ere seen which are probably of Carboniferous age. Prindle 
and Hess found the Etamparl series extending from the head of Victoria Creek to the Yukon 
at Rampart . 
I )eep snow and "out inuous storm made it impossible to complete the t raverse between the 
head of I [ess ( Yeek and Fori I lainlin, a distance of 60 miles: but from casual observations of 
quartzite, slate, sandstone, and diabasic and granitic hit rusives the writer believes that the 
Etamparl series forms the bed rock throughout the area. 
The strike of the rocks through this whole region varies from \. 50 E. to east-west and is 
most commonly N\ 65° E. From Birch Creek to Beaver Creek the structure consists 
broad folds, but between Beaver Creek and Yukon Flats on the west the dip reverses a 
shorter intervals, and in the limestone range north of Victoria Creek is nearly vertical. Th 
distance from cresl to crest of the folds jv several miles and the si rata usually dip 80° to |(l c 
IGNEOUS ROCKS. 
Tuffs and diabase appear frequently, associated with the stratified rock. A coarse 
grained biotite-granite with pink feldspars an inch or more long occurs between the heads o 
Preacher and Beaver creeks. It forms all of Rocky Mountain, which is capped by a cob 
spicuous castle-like ledge, and is abundant 8 or 10 miles east of Rocky Mountain, near th 
divide between Preacher and Birch creeks. This is the same kind of granite as that foun< 
by Prindle on Mastodon, Deadwood, and Portage creeks in the Birch ('reek region. Thi 
granite outcrops in conspicuous ledges from It) to 75 feet high and weathers to a coarse sand 
making a marked contrast with the quartzite surfaces with which it is in contact, (iranit 
also occurs abundantly above the junction of Victoria and Beaver creeks. 
"Spun, .1. i;.. Geology of the Yukon gold district, Uaska: Eighteenth \mm. Etept. U.S. Geol. survey 
pt.3, 1898, p. 155. 
