456 Scientific Intelligence. 



Dr. Spencer calls attention to the changes that are sure to 

 occur in the character of the falls and the river as the result of 

 power plants established at Niagara. If the concessions already- 

 granted are completely developed, the waters of the lakes will 

 decrease materially and the American falls will entirely dis- 

 appear. The level of Lake Erie has dropped eight inches already 

 as the result of the development of about one-fourth of the fran- 

 chise power. 



The detailed studies outlined above enable the author to reach 

 the following conclusions regarding the age of the falls : "The 

 time required for the recession of the double falls to Wilson 

 point (in addition to the 3,200 years mentioned) is found to have 

 been 31,600 years, and 700 years more to the head of Fqster flats, 

 the whole distance being nearly three miles. This was the length 

 of the gorge excavated during the Erie Epoch. From now 

 onward the recession was very rapid, modified at times, but in 

 all requiring only about 3,500 years, so that the age of Niagara 

 falls may be placed at about 39,000. Slight variations on one 

 side or the other are probable, but under the conditions, all of 

 which are now apparently known, the error in calculations will 

 not exceed ten per cent." (p. 11.) 



The book is admirably illustrated and contains valuable his- 

 torical matter. h. b. g. 



3. Michigan State Geological Survey. Alfred C. Lane, 

 State Geologist. Peat ; essays on its Origin, Uses and Distribution 

 in Michigan ; by Charles A. Davis. Pp. 105-361, 19 pis., and 

 19 figs. Lansing, 1907. — This book, issued as part of the 

 Michigan Geological Survey report for 1906 (see this Journal, 

 vol. xxv, p. 354), is deserving of wide recognition. It constitutes 

 practically the only available source of information on a question 

 which is much misunderstood. While the book is designed to apply 

 particularly to the peat deposits of Michigan, the discussion is so 

 general as to be practically a treatise on the whole subject. Part 

 I deals with the origin of peat, Part II with the peat bogs of north- 

 ern Michigan, Part III with the economics of peat. 



The discussion of peat origin necessarily involves a consider- 

 able treatise on ecology, a subject with which Professor Davis 

 is evidently much at home. The character of the peat-forming 

 plants and the conditions under which they thrive are explained 

 in detail. The discussion of the origin of peat bogs will interest 

 all geologists, for Professor Davis finds that, contrary to the 

 almost universally accepted idea, sphagnum moss is not an import- 

 ant factor in bog formation. "... peat is chiefly formed by plants 

 which grow below or very near the water level, aquatic plants 

 in connection with sedges, and other grass-like plants ; Sphagnum 

 does not appear until late in the history of the formation, if at 

 all, and develops only shallow, superficial layers of peat and 

 usually grows best in association with certain shrubs, which may 

 become prominent before the Sphagnum appears, and which may 

 also reduce its effectiveness in peat-forming by developing dense 



