230 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



in the Sinclair section 100 miles (160.9 ^^•) south-southeast of 

 Glacier Lake on the west side of the Continental Divide, where the 

 general character and the fauna of the Sabine are the same as at 

 Glacier Lake. 



The lower boundary of the Lyell in the Sawback Range is placed at 

 the base of a band of reddish-brown, arenaceous shales and limestones 

 that occur beneath a series of thick-bedded, more or less magnesian 

 limestones. In the Glacier Lake section there are 430 feet (131.1 m.) 

 of gray limestone beneath 1,270 feet (387.1 m.) of massive-bedded, 

 partly magnesian limestones. 



The fossils from the Lyell indicate that the formation is : ( i ) 

 younger than the Sherbrook of the Bow Trough and the Ottertail 

 of the Goodsir Trough; and (2) possibly older than the Sabine of 

 the Beaverfoot, Glacier Lake and Sawback Troughs. 



Fauna. — Very few fossils have been found in the Lyell limestones. 

 In the Glacier Lake section none was seen in the upper 1,320 feet 

 (402.3 m.) except an occasional annelid trail or boring. A bed of 

 hard, slabby limestone here broke the series of thick-bedded, rough- 

 weathering limestones, and on the surface of some of the thinner 

 slabs, valves of a small Lingidella sp. and a few graptolites were 

 found. The latter included a well-preserved new species of Dendro- 

 graptus, D. ramosissimiis Rued., and a new genus and species, Masti- 

 gograptus macrotheca Rued. The genus Dcndrograptiis is of late 

 Upper Cambrian age in the upper Mississippi Valley. Six feet ( 1.8 m.") 

 above the base of the Lyell at Glacier Lake, fragments of two species 

 that suggest Anamocarclla^ occur, but they are of little value in 

 determining the stratigraphic position of the Lyell formation. No 

 fossils were seen in the Clearwater Canyon section of the Lyell (E on 

 map, pi. 26). but about 19 miles (30.6 km.) southeast of Clearwater 

 Canyon, in the Tilted Mountain Cirque section (see p. 291) many 

 fragments of small trilobites were found and the genera Conaspis 

 and Kingstonia were identified. 



At about the same horizon in the Ranger Canyon section (H on 

 map), beneath the great limestone 1,325 feet (403.9 m.) thick, species 

 of the following genera were collected : Agnostus, Irvingella, and 

 Saratogia. 



No fossils were seen in the Lyell of the Beaverfoot Trough in 

 the Brisco-Stanford Range. 



Observations. — The Lyell limestones were deposited under nearly 

 uniform conditions in the Glacier Lake, Sawback, and Beaverfoot 



^ Research in China. Carnegie Inst, of Washington, Vol. Ill, 1913, pp. 195-210, 

 pis. 19-21. 



