Geology. 239 



Vermont. Of great interest are the papers by C. H. Richardson 

 recording the finding of Lower and Middle Ordovician graptol- 

 ites in highly metamorphosed slates and marbles in central Ver- 

 mont throughout an area 40 miles wide and 100 long. No one 

 ever thought of finding fossils in these greatly altered strata, and 

 the new discoveries will not only enable the geologists to deter- 

 mine the age of the formations but also help much to a fuller 

 realization of the rock structures and their times of deformation. 



c. s. 



10. Geology and Natural Resources of Rutherford County, 

 Tennessee; by J. J. Galloway. Tennessee State Geol. Survey, 

 Bull. 22, 31 pp., 3 pis., 1 map, 1919. — A good modernization of the 

 geology of one of the most interesting counties of central Ten- 

 nessee. The stratigraphy relates in the main to the Ordovician, 

 and the Chattanooga is referred to the early Mississippian. The 

 geologic map is on the scale of one inch to the mile. c. s 



11. Geologic Map of Ohio; by J. A. Bownocker and associ- 

 ates, 32 X 39 inches, 1920. — This is one of the best state geological 

 maps of the many that have been published in recent years. The 

 scale is about 8 miles to the inch, or 1 : 500,000. The color 

 scheme brings out clearly the various formations mapped (14) 

 and the printing is excellent. There are no contour lines, but the 

 original map was made on a contour base. The formation 

 boundaries are shown in great detail. Besides the geology, there 

 is given the detailed geography, drainage, culture, oil- and gas- 

 producing areas, shipping coal mines, and other economic loca- 

 tions, c. s. 



12. Seasonal Deposition in Aqueo- glacial Sediments; by Rob- 

 ert W. Sayles. Mem. Mus. Comp. Zoology, vol. 47, No. 1, 67 

 pp., 16 pis., 2 text figs., 1919. — The author here first describes 

 and illustrates by heliotype plates the nature of the Pleistocene 

 annual-layered clay beds, and then applies this knowledge to the 

 Permian slates at Squantum, Massachusetts, with the result that 

 there can be no doubt that their banding is glacial and seasonal. 

 He adds a survey of the banding described by geologists of many 

 lands and observed also in museum specimens, coming to the con- 

 clusion that some of the slates accompanying most tillites since 

 the Huronian are certainly seasonally banded. As tillites are 

 not so readily preserved in the geologic record as are the marine 

 clays of glacial times, we are asked to be more on the lookout 

 for them and thus to further assist in determining the rigorous 

 climates of the past. It was Edward Hitchcock who in 1841 

 first called attention to the banding in Pleistocene clays as prob- 

 ably due to annual changes in deposition. Since his time, several 

 other American geologists have come independently to the same 

 conclusion regarding the Pleistocene clays, but it was DeGeer of 

 Sweden who in 1912 placed this theory on a firm basis. Now 

 Sayles applies it successfully to almost all of the older glacial 

 accumulations. c. s. 



13. Middle Cambrian Algm and Middle Cambrian Spongice; 



