42 
108 Eldridge (George H.). Artesian wells of eastern Dakota. 
Int. Cong. Geol., Compte Kendu, 5th session, p. 318. 
Describes the character of the strata from which artesian water is 
obtained and gives the depths of the wells. 
169 Elftman (Arthur Hugo). Preliminary report of field work during 
1893 in northeastern Minnesota. 
Minn. Geol. and Nat. Hist. Surv., 22d Ann. Rept., pp. 141-180. 
Describes the topography of portions of Lake County and the dis- 
tribution and petrographic characters of the granite, actinolite-mag- 
netite schist, gabbro, red rock, diabase, and anorthosyte of north- 
eastern Minnesota. 
170 Ells (R. W.). Mica deposits in the Laurentian of the Ottawa dis- 
trict. 
Geol. Soc. Am., Bull., vol. v, pp. 481-488. 
Abstract: Am. Geol., vol. xiii, p. 215 (6 1.). 
Describes the metamorphosed sedimentaries and intrusive rocks of 
this district, the occurrence of apatite and mica, and the differences 
in the mica-apatite deposits. 
171 Emmons (Samuel Franklin). Description of the Elk Mountains 
[Anthracite-Crested Butte folio, Colorado]. 
U. S. Geol. Surv., Geologic Atlas of the United States, folio 9. 
Gives a historical sketch of the geology of the region and describes 
the clays, iron ore, and precious metal deposits. Includes a topo- 
graphic, colored geologic, economic, and structure section maps of 
each of the districts and a sheet of columnar sections. 
172 Geological distribution of the useful metals in the United 
States. 
Am. Inst. Mg. Engrs., Trans., vol. xxii, pp. 53-95 and 737-738. 
Describes the geologic occurrence in different parts of the United 
States of iron, manganese, nickel, tin, copper, lead, zinc, quicksil- 
ver, gold, and silver, and gives a summary of conclusions concerning 
the genesis of their minerals. 
173 [The genesis of ore deposits.] 
Am. Inst. Mg. Engrs., Trans., vol. xxiii, pp. 597-602. 
Discussion of paper by F. Posepny on the same subject. 
174 Congres Geologique International, Compte Rendu de la 5 me 
session, Washington, 1891, ix -f 529 pp., pis. i-xxi, figs, 1-39. 
Edited by S. F. Emmons, secretary. 
Contains a historical sketch of the Congress, report of the sessions, 
a description of the geology of Washington and vicinity, the geology 
of the region traversed by the excursion to the Rocky Mountains 
and the Grand Canyon of the Colorado, and of the excursion to Lake 
Superior. 
174a Guidebook of an excursion to the Rocky Mountains. 
John Wiley & Sons, 1894, New York. 
Describes the geology along the route traversed by the western 
excursion of the International Congress of Geologists from Washing- 
ton, D. C, to Chicago, St. Paul, Yellowstone National Park, Snake 
Plains, Great Salt Lake, Leadville, Denver, Canyon of the Colorado, 
Kansas City, Chicago, Niagara Falls, and to New York City. 
Extract from Compte Rendu, Int. Cong. Geol., 5th session. 
