6UHFACE PUENOiTENA. 187 



Sternberg, H. [Researches on the Form of the Longitudinal and 



Cross Sections of Gravel-Bearing Rivers.] Zeitschriftjur Bauwesen^ 



vol. XXV. pp. 483-50G. (Abstract in Proc. Inst. Civ. Eng. vol. xliv. 



pp. 258-261.) 



A mathematical inquiry into the conditions of the abrasion and 



transportation of boulders, and into the form of an ideal cross section, 



which should remain unchanged, the velocity remaining constant at all 



levels, and the transport of gravel being continuous. It is necessary 



that the channel should be bounded by catenary curves. In most 



watercourses, from the wetted perimeter being too great when the 



water is low, and too small when the water is high, the boulders are 



not kept in motion in the former case, and are transported impetuously 



in the latter. F. D, 



Symonds, Rev. W. S. Among Glaciers Recent and Extinct. Pop. 

 Sci. lieu. vol. XV. pp. 109-182. 



A general account of glacial action — of the oscillation of Swiss 

 glaciers within recent years, and their great extension during the 

 Glacial period, and of the glaciation of Britain and the Glacial deposits 

 of the E. of England. The last stage of thc^ Glacial period in Britain 

 was a return of the glaciers on the Highlands and heavy falls of snow 

 on the lower hills, the melting of which in summer caused great floods 

 over the lower lands. This was after the days of the cave-men ; the 

 return of glacial conditions destroyed the mammoth and the tichorhine 

 rhinoceros. W. T. 



Tor ell, Prof. Otto. On the Glacial Phenomena of 'North. America. 

 Proc. Amer. Assoc. Abstract in Neiv Yorlc Times^ Aug. 30, and 

 Aiiier. Jour a. ser. 3, vol. xiii. pp. 76-79 (1877). 

 Describes deposits produced by glaciers in advancing and retreating. 

 The American drift came from the N.E. (Greenland). 



Tylor, A. Denuding Agencies and Geological Deposition under the 

 Flow of Ice and Water, with the laws which regulate these actions, 

 and the special bearing on river-action of observations on the 

 Mississippi and other great rivers, and their present and past 

 Meteorological conditions, and similar remarks on Marine Deposits, 

 illustrated by the Irish Sea and the Clicsil Beach. Geol. Mag. 

 dec. ii. vol. iii. pp. 90-93. Fuller abstract than in Quart. Joum, 

 Geol. iSoc. vol. xxxii. Proceedings, pp. 4-9. 

 The present contours are mainly due to a Pluvial period. The rain- 

 fall is greater in summer than in winter. Flexures, not fractures, 

 determined the valley system of the Weald. Longitudinal sections of 

 large valleys are parabolic curves. Curve of denudation is a more 

 correct term than plane. Tidal waves do not coincide with the time of 

 high water, which depends on local causes. A slight horizontal motion 

 of the central mass of the ocean will produce great vertical motion on 

 the shores. W. H. D. 



