Geological Society. 73 



votes to the study of a work like the present, which gives with 

 great clearness, accuracy, and brevity the facts of the subject 

 clothed, as far as may be,' in the language of daily life. 



The illustrations are sufficiently numerous : some of them are little 

 more than diagrams ; others are elaborate drawings of instruments, 

 and are very good, e. g. those on p. 60 and p. 102. There are also 

 two whole pages of coloured figures (which are very beautifully 

 done), showing the rings and brushes produced by polarized light 

 in the case of six crystals, two complementary figures for each 

 crystal. In cou elusion we can cordially recommend the book to 

 the somewhat select class of readers who take an intelligent interest 

 in this beautiful branch of science. 



IX. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from vol. xlviii. p. 546.] 

 February 4, 1874.— His Grace the Duke of Argyll, K.T., F.R.S., 



President, in the Chair. 

 ^HE following communications were read : — 

 -*- 1. "The Physical History of the Valley of the Rhine." By 

 Prof. A. C. Ramsay, LL.D., V.P.R.S., Vice-President. 



The author first described the general physical characters of the 

 valley of the Rhine, and discussed some of the hypotheses which 

 have been put forward to explain them. His own opinion was that 

 during portions of the Miocene epoch the drainage through the 

 great valley between the Schwarzwald and the Vosges ran from the 

 Devonian lulls north of Mainz into the area now occupied by the 

 Miocene rocks of Switzerland. Then after the physical disturb- 

 ances which closed the Miocene epoch in these regions, the direction 

 of the drainage was reversed, so that, after passing through the 

 hill-country between the lake of Constance and Basel, the river 

 flowed along an elevated plain formed of Miocene deposits, the 

 remains of which still exist at the sides of the valley between Basel 

 and Mainz. At the same time the Rhine flowed in a minor valley 

 through the upland country formed of Devonian rocks which now 

 constitute the Taunus, the Hundsruck, and the highland lying 

 towards Bonn ; and by the ordinary erosive action of the great river 

 the gorge was gradually formed and deepened to its present level. 

 In proportion as the gorge deepened, the marly flat Miocene strata 

 of the area between Mainz and Basel were also in great part worn 

 away, leaving the existing plain, which presents a deceptive ap- 

 pearance of having once been occupied by a great lake. 



2. "On the Correspondence between some Areas of Apparent 

 Upheaval and the Thickening of Subjacent Beds." By W. Topley, 

 Esq., F.G.S., Geological Survey of England. 



The author referred to maay instances in w r hich beds have unequal 

 development, being much thicker in some places than in others ; 

 and the main object of his paper was to show that such thickening 

 and thinning of beds has an important effect in producing the 

 apparent dip of overlying beds. The thinning of any one bed may 



