CAMP CREEK SERIES 3 



of a great mass of Cambrian limestone, extending 6 miles on a northwest- 

 southeast axis and varying in width from one to two miles (see plate 2, 

 figure 1). The southeast point is Scapegoat (9,185 feet elevation) and 

 the northwest elevation (9,000 feet) I shall call Cambria. The lime- 

 stones are superjacent to siliceous Algonkian strata forming the main 

 ridge of the Continental divide and the spurs descending from it on the 

 north, west, south, and southeast. On the east and northeast the Cam- 

 brian limestones slope toward the Dearborn Eiver drainage. 



After a reconnaissance of the area I decided to measure the Algonkian 

 section at localities where each of its units, or formations, were well 

 exposed and in contact above and below with other known formations. 



For the first, or upper, series of strata the sharp ridges on the 

 southeast and northwest sides of Camp creek were selected (see plate 2, 

 figure 2). Camp creek heads close to the Continental divide, northwest 

 of Trap mountain, and 12 miles northwest of Cambrian point. It flows 

 south-southwest to where it enters Danaher creek, 4 miles above the head 

 of the south fork of the Flathead river.* 



Cambrian, Flathead sandstones. — The massive, coarse grained sand- 

 stones of the Flathead series overlie the Algonkian strata of the Camp 

 Creek, Mission Eange section at the summit of the Continental divide. 



The fine 'conglomerate at the base of the Flathead sandstone of the 

 Middle Cambrian rests in apparent conformity on the Algonkian strata, 

 the layers of both formations dipping north at an angle of 70 degrees. 



Algonkian, Belt terrane. — The Algonkian strata of the Camp Creek, 

 Mission Eange section, comprise three great series, the Camp Creek, the 

 Blackfoot, and the Eavalli, as follows: 



Camp Creek series 



la. Compact, bard, gray sandstones, almost quartzitic in Feet Feet 

 many layers ; layers vary in thickness from one-fourth 

 inch to 10 inches ; often marked by mud cracks and rip- 

 ples ; toward the top the dip is about 70 degrees north ; 

 500 feet in thickness below, the dip increases to 80 

 degrees, and decreases to 75 degrees near the base. . . . l,762f 1,762 



From this point the section was measured on the east 

 side of Camp creek. 



2a. Reddish brown, arenaceous shales and thin bedded lime- 

 stones, alternating irregularly with greenish gray 

 bands of shales and sandstones. Some of the thicker 

 layers, 2 to 6 inches, are almost quartzitic . . 1,560 1,560 



* See topographic map of Ovando quadrangle, Montana. 



t All thicknesses, unless otherwise stated, were obtained by measuring the strata 

 with rod and clinometer, a method that gives reliable results. (See Proc. U. S. Nat. 

 Museum, 1888, vol. xi, p. 447.) 



