BIBLIOGRAPHY OF NORTE AMERICAN GEOLOGY, 1906-1901. 95 
Hidden, W. E., and Warren, C. II. 
1143. On yttocrasite, a new yttrium-thorium-uranium titanate. — Am. Jour, 
Sei., 4th ser., vol. 22. pp. 515 519, December, 1906; Zeitschr. f. Krystal. u. 
Mineral., Bd. 44. Heft 1, pp. 18-23, 1007. 
Hilgard, E. W. 
1144. Soils: their formation, properties, composition, and relations to cli- 
mate and plant growth in the humid and arid regions. Now York. The Mac- 
Millan Company, . 1906. 503 pp., so figs. 
1145. Some peculiarities of rock-weathering and soil formation in the arid 
and humid regions. — Am. Jour. vSci., 4th ser., vol. 21, pp. 261-269, April, L906. 
1146. The exceptional nature and genesis of the Mississippi delta. Science. 
new ser., vol. 24, pp. 861-866, December 28, 1906. 
1147. The causes of the glacial epoch. — Congr. geol. intern.. ( \ R. 10" sess., 
.Mexico, 1906, pp. 431-436, 1907; Science, new ser., vol. 25. pp. 350-354, March 
1,1907. 
1148. Exceptional nature and genesis of the Mississippi delta. — Abstract: 
Geol. Soc. America, Bull., vol. 17. p. 731, 1907. 
Hill, Robert 4'. 
1149. The volcano systems of the western hemisphere. Several groups of 
active volcanoes. — The Century Magazine, vol. 64, no. 3. pp. 473 483, 13 figs., 
July, 1902. 
1150. On the origiu of the small mounds of the lower Mississippi Valley 
and Texas. — Science, new ser., vol. 23. pp. 7<»4 706, May 4, 1906. 
1151. Geologic and geographic aspects of Mexico. — Min. World, vol. 25, pp. 
370-372. 450. 540-541, 596, 7 figs., 1906; vol. 2(5. pp. 00. 187, 1907; vol. 27, pp. 
589-501, 033 (134. 805, figs., 1007. 
1152. Geology of the Sierra Almoloya. with notes on the tectonic history of 
the Mexican plateau.— Science, new ser.. vol. 25, pp. 710-712, May 3, 1007. 
1153. Peculiar formations of the Mexican arid regions. — Eng. and Min. 
Jour., vol. S3, pp. 062-666. 3 figs., April 0, 10<»7. 
Discusses physiographic features and the mode of their formation. 
1154. Characteristics of some Mexican mining regions. — Eng. and Min. Jour., 
vol. 84, pp. 031 636, 8 tigs., October 5, 1907. 
Discusso* physiographic features and economic resources of Chihuahua, Sonora, and 
the western Siena Madre. 
1155. Geology of the Sierra Almoloya. Mexico. — Min. World, vol. 20. pp. 
530-532, 500. o figs., 1907. 
1156. Mexico: Its geology and natural resources. — Min. World, vol. 27. pp. 
686 691, 1<> tigs.. October 26, 1007. 
Hille. F. 
1157. The Atik-Okan nickeliferous pyrrhotite deposits and their origin. — 
Canadian Min. Inst.. Jour., vol. 0. pp. 285 301, 1 pi. (map), 4 tigs.. 1906. 
Describes the rock formations of the region and discusses the origin <>t" the iron ores. 
1158. Preliminary report on (he iron ore deposits of western Ontario. — 
Canada, Dept. Interior. Kept. Snpt. Mines. 1907, pp. 13 is. L907. 
Hillebrand, W. V. 
1159. Notes on the chemical composition of the roofing slates of eastern 
New York and western Vermont.- ('. S. Geol. Survey, Bull. no. 275, pp. -".'.t 12, 
1000. 
1160. The analysis of silicate and carbonate rocks. I', s. Geol, Survey, 
Bull. no. 305, 200 pp.. 21 figs., 1007. 
