408 REVIEWS 



Devonian farther west than any previous map but the margin of the 

 sediments farther east, except for the New Jersey strait of Schuchert 

 which is here eliminated." The Upper Devonian sediments are believed 

 to have extended northward beyond Lake Ontario and as far eastward 

 as the margin of the present coastal plain; their removal over a great 

 part of this area is referred to pre-Newark (Mid-Triassic), Jurassic, and 

 post-Jurassic (Comanche and Cretaceous) erosion epochs. These 

 Upper Devonian beds apparently formed a great piedmont plain that 

 stretched westward from Appalachia; the Skunnemunk conglomerate 

 (2,500 feet thick) is a remnant. This plain thickened from east to west 

 and in so doing changed from coarse to fine sediments. The indications 

 are that the drainage divide of Appalachia "was at least as far east as 

 the present 100-fathom line southeast of Long Island and New Jersey." 



V. O. T. 



Geology and Ore Deposits of the Monarch and Tomichi Districts, 

 Colorado. By R. D. Crawford. Bull. Colo. Geol. Surv. 

 No. 4, 1913. Pp. 317, pis. 15 (including 4 maps), figs. 15. 



The Monarch district lies in the southwestern part of Chaffee 

 County, Colorado, on the east slope of the Sawatch Range. The 

 Tomichi district, which is in Gunnison County, is on the west slope of the 

 range and joins the Monarch district on the west. 



The sequence of formations is as follows: pre-Cambrian gneisses, 

 schists, granites, pegmatite, and quartzite; the probably Upper Cam- 

 brian Sawatch quartzite (20=*= feet); the mid-Ordovician Tomichi 

 limestone (400 feet); the Upper Devonian and early Mississippian 

 Ouray limestone (600-S00 feet); the Pennsylvania Garfield formation 

 (2,800 feet); the Permo-Pennsylvanian (?) Kangaroo formation (about 

 3,000 feet); post-Carboniferous quartz monzonite, granular rocks, 

 porphyries, flow, and volcanic breccia; Pleistocene and later glacial 

 and fluvio-glacial deposits; recent deposits. 



The Sawatch quartzite does not outcrop in the Monarch district. 

 In the Tomichi district, the Garfield formation is only a few hundred 

 feet thick, and the Kangaroo formation is wanting. 



Unconformities exist between the following formations: the pre- 

 Cambrian and Sawatch, the Sawatch and Tomichi, the Ouray and 

 Garfield, the Garfield and Kangaroo, the Kangaroo and volcanic 

 breccia, the Pleistocene and older deposits. Regarding the interval 

 between the Tomichi and Ouray, the author notes that "although one 



