AMERICA. 119 



the submergence of the central country, and carried the drift material 

 with it. As submergence went on, the sea reached the base of the llocky 

 Mountains ; and hence was derived the quartzite drift which chiefly 

 occurs over the higher prairies. W. T. 



Dodge, W. W. Notes on the Geology of Eastern Massachusetts. 

 Proc. Boston Soc. Nat. Hist. vol. xvii. pt. 3, pp. 388-419. 



I. Crystallines ; II. Stratified Rocks, Slates, Conglomerates, Norfolk 

 County Basin ; [III. ?J Eruptives ; [IV.?] Glacial Effects. 



Enilich, Dr. F. M. lleport on the Mines and Geology of the San 

 Juan Country. Bull. U.S. Geol. Surv. Territories, ser. 2, no. 3, 

 pp. 151-161 ; plate (Map of Baker's Park). 



Fojr sets of trachytes, 7000 to 8000 feet aggregate thickness, are 

 followed by rhyolite, doleritc, and basalt. Schistose rocks underlie the 

 volcanic. The lodes strike X.E. or N.W., their visible outcrops being 

 often of great vertical height. 15 are named and mapped, their strikes, 

 ores, and the extent of work being given. The gangiie is mostly qu irtz : 

 the ores are galeuite with silver, sphalerite, pyrite, chalcopyrite, gold, 

 psilomelane, and fahlerz or freibergite (antimonial tetrahelrite with 

 silver, iron, and zino). The lodes are probably of late Cretaceous age. 

 The map shows Carboniferous (2 divisions). Cretaceous (2 divisions), 

 Metamorphic and Volcanic rocks. W. H. D. 



Fontaine, Wm. M. On some points in the Geology of the Blue 

 llidge in Virginia. Amer. Joiim. ser. 3, vol. ix. pp. 14-22, 

 93-101. 

 A detailed description, chiefly of the Pre-Silurian rocks of this dis- 

 trict, which appear to consist of a thick series of argillites (the line of 

 demarcation between them and the Silurian being clearly shown) and 

 of a variety of highly metamorphic rocks from granite and gneiss to 

 epidosite, and an eruptive-looking rock called provisionally '* pinite 

 pori)hyry." G. A. L. 



. On the Primordial Strata of Virginia. Amer. Journ. ser. 3, 



vol. ix. pp. 361-3fJ9, 416-428; 3 figs, in text. 

 Detailed descriptions of the lie of the rocks in the Blue Ridge and 

 adjoining regions. 



Ford, S. W. Note on the Discovery of a new locality of Primordial 



Tossils in Rensselaer County, N. Y. Amer. Journ. ser. 3, vol. ix. 



pp. 204-206. 



The locality is E. of the \'illago of Lasingburgh ; and the fossils were 



found in a brecciatod limestone : they were perfect specimens of the 



pygidium of ConocepJuilites (Atops) trilineatus, Jfj/olithes Americamis, 



Ohiddla nitida. The writer regards this " lime r*ck " as the equivalent 



of his limestone band No. 1 at Troy. G. A. L. 



Foster, Ernest La N. Something about Colorado ; its iMines and 

 ^[inerals. Ann. R^p. Miners' Assoc. Cornwall for 1874, and 

 part of 1875, pj). 03-05. 

 ' Coal, probably Tertiary, is mined in several places ; iron-ore is littln 



