164 James Geikie — On Changes of Climate. 



The last objection is greatly confirmed by the overhanging cliffs 

 and numerous blocks of porpliyrite which lie scattered on the beach, 

 as if to attest the former extension of that ancient sheet of which 

 these blocks now form but a small remnant. Indeed, the existence 

 of such remains appears sufficient of itself to condemn any hypothesis 

 which presumes the present face of the cliff to have formed the 

 original boundary of the mass. 



It may be fairly objected to our theory, as Prof. Geikie himself 

 has suggested, that the high angle at which the strata dip is difficult 

 to account for. But, in fact, this steep inclination constitutes the 

 very difficulty which any hypothesis on the subject must be framed 

 to explain; and it is a difficulty which is not more easily solved 

 by Prof. Geikie's theory than by our own. 



V. — On Changes of Climate during the Glacial Epqch. 



By James Geikij:, F.E.S.E., 

 District Surveyor of the Greological Survey of Scotland. 



Fifth Puper. 



{Continued from the March Number , p. 111.) 



THE older valley-gravels and cave-deposits of England contain, as 

 every geologist knows, a remarkable intermingling of northern 

 and southern forms of animal life. To account for this anomaly 

 various theories have been advanced. There are few who do not 

 admit, to begin with, that species such as the hippopotamus and the 

 musk-sheep could not have lived side by side throughout the year in 

 the same country. The conditions necessary for the support of the 

 one would be fatal to the other. Some writers, therefore, have 

 inferred that the occurrence of the remains of both these creatures 

 in our superficial deposits points to former fluctuations of climate 

 during the accumulation of these beds ; while others hold that it 

 only indicates a period of strongly contrasted summers and winters. 

 There are yet other theories which have been put forward to explain 

 the difficulty. Mr. Prestwich, for example, has suggested that the 

 hippopotamus was possibly protected by a coat of fur, and may thus 

 have been able to exist under the same climatal conditions as the 

 musk-sheeg, the mammoth, and the Siberian rhinoceros. But the 

 hippopotamus is not the only animal that would seem to indicate 

 that, at some period during the formation of the valley-gravels and 

 cave-deposits, the climate of Britain was comparatively warm, — 

 Meplias antiquus and the two rhinoceroses {B. megarJiimis and 

 JB. leptorhiims) appear to tell the same story. It is hardly possible 

 to believe that all these species were fitted like the mammoth to 

 brave the exigencies of a severe climate. The more reasonable view 

 is ithat adopted by most palasontologists, namely, that the hippo- 

 potamus, the elephant, and the two rhinoceroses are true southern 

 forms, and could only have existed in Britain under mild or compar- 

 Mively warm conditions. At all events, as regards the hippopotamus 



