392 Searles V. Wood, Jun, — The Climate Controversy . 



The theory that the oceanic currents are due to the action of the 

 trade winds is old, but the intimate connexion which Mr. Croll 

 shows to exist between the general oceanic and atmospheric circu- 

 lations is very striking. The influence, however, of these currents, 

 except so far as their direction may be supposed to be altered by 

 the alternate glaciation of the two hemispheres from the position of 

 aphelion, is applicable equally to theory No. 4. To that theory, 

 however, and to the one under consideration, there arises the objec- 

 tion, so far as the Glacial period proper is concerned^ that the 

 distance to which the evidences of glaciation extend southwards 

 on the eastern side of North America, beyond what they do in 

 Europe, seem to indicate that the portion of the oceanic circulation 

 to which the existing differences in climate between corresponding 

 latitudes in Europe and North America are due could not have 

 differed much during that period from what obtains now. 



The theory requiring that there have been many periods of high 

 excentricity, during every one of which there were one or more minor 

 periods of about 10,500 years when the opposite hemispheres were 

 subjected to the alternate conditions of glaciation and warmth, Mr. 

 Croll endeavours to prove by two things. One of these is that glacial 

 periods embracing such minor periods of alternation have occurred 

 at different stages in the Geological record ; and the other, that the 

 evidences preserved of that particular period which we are accus- 

 tomed to call the Glacial afford proof of there having occurred 

 during its progress repeated alternations of climate, or, in other 

 words, interglacial periods of warmth. As to the first of these, 

 he has (as Sir Charles Lyell has, as regards some of the instances, 

 also done in his " Principles ") collected various notices by geologists 

 of formations considered to be indicative of ice action, belonging to 

 Silurian, Devonian, Carboniferous, Jurassic, Cretaceous, Eocene, and 

 Miocene ages respectively ; and they no doubt to some readers 

 have a very convincing appearance ; but to others they induce more 

 perplexity than conviction. In my own case, not being so familiar 

 with the Palaeozoic and Mesozoic formations as with the Tertiarj'^, 

 I read these instances of Palaeozoic and Mesozoic glaciation with 

 respect, though not conviction ; but when I come to the Eocene and 

 Miocene instances, facts clashing entirely with them present them- 

 selves. In the case of the Eocene, we are offered the evidence of 

 the occurrence, in the unfossiliferous Flysch of the Alps, of a bed 

 containing blocks of all dimensions up to the size of an ordinary 

 church ; and in the Miocene the evidence of a North Italian bed 

 containing blocks both of large dimensions and striated. Now the 

 Eocene formation is complete in England, and is exposed in con- 

 tinuous section along the north coast of the Isle of Wight from its 

 base to its junction with the Oligocene (or Lower Miocene according 

 to some), and along the northern coast of Kent from its base to the 

 Lower Bagshot Sand. It has been intersected by railway and other 

 cuttings in all directions and at all horizons, and pierced by wells 

 innumerable ; while from its strata in England, France, and Belgium, 

 the most extensive collections of organic remains have been made 



