abstracts: geology 467 



posed, but along the Cannonball River, just south of this area, the 

 formation has a thickness of 200 feet. Overlying this over most of 

 the area, in apparent conformity, are 650-700 feet of dark, gray, brown, 

 and black shale and sandstone of the Lance formation (fresh water), 

 the approximate equivalent of the Ceratops beds of Wyoming. In this 

 there is at least one workable 5-foot bed of lignite. 



Conformably overlying the Lance or "Somber beds" are the ash- 

 gray and yellow shales and sandstone of the Fort Union (Tertiary), 

 having a maximum thickness of 200 feet. In this are numerous beds 

 of lignite ranging in thickness from a few inches to 35 feet,^ — -thick- 

 nesses of 5 to 10 feet are common. In places the lignite has burned 

 out along the outcrop baking the overlying shale to red or pink 

 clinker. The Fort Union carries a rich fossil flora, many freshwater 

 shells and a few vertebrate fossils. 



The area, altho outside of the terminal moraines of the Wisconsin 

 stage of glaciation, contains considerable glacial drift. Remnants of 

 moraines, patches of till, and patches of boulders are found, the latter 

 so abundant in places as to form a pavement. This drift, tho indicated 

 on the map as probably of Early Wisconsin age, is in the text provi- 

 sionally referred to the Kansan stage of glaciation, since the appearance 

 is that of remnants of a much eroded deposit. The western limit of 

 continental glaciation is 50 to 60 miles west of the Missouri in this 

 latitude. Much of the dissection of the area is believed to have been 

 accomplished in Tertiary time but it also appears that there has been 

 a long period of erosion since the deposition of this drift. The valley 

 of Missouri River the author regards as pre-glacial. The economic 

 resources of the area are lignite, clay, gravel, sand, surface and under- 

 ground waters, and a good soil. Wm. C. Alden. 



GEOLOGY.- — Geologic reconnaissance of a part of the Bampart Quad- 

 rangle, Alaska. H. M. Eakin. Bulletin U. S. Geological Survey 

 No. 535. 

 The area treated is in central Alaska, between Yukon and Tanana 

 Rivers west of the 150th meridian. The consolidated stratified rocks 

 of the area include a greenstone group probably of late Paleozoic age, 

 a limestone and schist group of earlier Paleozoic age, a slate, quartzite 

 and schist group, in part of Lower Cretaceous age and a slate sand- 

 stone and conglomerate group, probably also of Mesozoic age. These 

 groups trend northeast and southwest across the area in a series of 

 belts, the succession from northwest to southeast being in the order 

 given. 



