Geology and Mineralogy. 24.7 



SCIENTIFIC INTELLIGENCE. 



I. Geology and Mineralogy. 



1. The Glacial Gravels of Maine and their associated deposits; 

 by George H. Stone. IT. S. Geo], Survey, Monograph XXXIV, 

 pp. 1-499. — Ever since the early writings of Agassiz on the 

 glacial geology of New England, the "horsebacks " and terraces 

 of Maine have been generally known, but the great extent and 

 remarkable perfection of the glacial deposits is a recent discovery. 

 Prof. Stone's work, extending over a period of thirteen years, has 

 resulted in a series of maps showing the distribution of the water- 

 laid sediments of glacial time over the whole state. The deposits 

 from each glacial stream have been mapped and grouped into 

 some sixty gravel "systems." Each "system" is composed of 

 trunk stream (usually an esker) with tributaries and distribu- 

 taries (delta branches). Under separate heads a detailed descrip- 

 tion is given of composition, shape,, etc., of each group. The 

 gravel " systems" are usually 10-25 miles in length ; the Houlton 

 "system" is 115 miles long and the Katahdin stretches out for 

 125 miles. The longer "systems" extend for many miles like an 

 artificial roadway carefully constructed, and with the exception of 

 Sweden constitute the finest examples of gravel ridges in the 

 world. 



This reconstruction of the river systems of glacial time has 

 been done with great labor, for there are no adequate maps of 

 Maine and much of the region is a succession of swamps and 

 forests. The fifteen maps accompanying the monogram show at 

 once the difficult nature of the work and the remarkable develop- 

 ment of the forms of drift in the state. The chapters on Classi- 

 fication and Genesis are valuable not so much because of the 

 theoretical conclusions drawn as for the great mass of detailed 

 description and discussion of the abundant material at hand. 

 Much has been done in glacial geology since the manuscript for 

 this monograph was completed (1889), but we know of no more 

 important contribution to the general discussion of eskers. Be- 

 sides the treatment of eskers space is given to descriptive and 

 theoretical matter in regard to kames, coast gravels, valley drift 

 and tills. A study of the till and the marine clays was made to 

 determine whether there was an interglacial period in Maine as 

 in the Mississippi Valley, but the evidence was found to point to a 

 single glacial period. h. e. g. 



2. The Illinois Glacial Lobe; by Frank Leverett. U. S. 

 Geol. Survey, Monograph XXXVIII, pp. 1-797, with 18 maps 

 and 15 illustrations. — This is the most elaborate volume on Glacial 

 Geology yet published and renders accessible the mass of facts 

 gathered during many years of research by a force of geologists 

 under the direction of Prof. Chamberlain. The pi'oblem before 

 Mr. Leverett was the investigation of the complicated phenomena 



