380 Mr. J. Croll on Geological Time, and the probable 



hemisphere, even up to the North Pole ; for it has been proved 

 that Greenland at this time must have been free of ice and covered 

 with a luxuriant flora. (See Heer's Flora Fossilis Arctica.) The 

 facts are wholly inexplicable on the ordinary theories of climate. 

 The cosmical theory, however, not only explains them, but they 

 follow according to this theory as a necessary consequence; for 

 if it should actually turn out that there is no such thing as a 

 warm and equable condition of climate somewhere about the 

 time of an ice-period, then the whole theory would have to be 

 given up, because a warm period, according to theory, is just 

 as necessary a result of an increase of excentricity as a cold period. 



The occurrence of a warm condition of climate close beside a 

 cold condition is not a mere accidental circumstance which has 

 only been observed during the Upper-Miocene period. For 

 when we go back to the Middle-Eocene period, we lind the 

 " fiysch," which bears the marks of having been formed during 

 an ice-period, closely associated with the nummulitic strata, in- 

 dicating a warm condition of climate. " It has always been 

 objected/'' says Sir Charles Lyell, "to the hypothesis that these 

 huge masses were transported to their present sites by glaciers 

 or floating ice, that the Eocene strata of nummulitic age in 

 Switzerland, as well as in other parts of Europe, contain genera 

 of fossil plants and animals characteristic of a warm climate. It 

 has been particularly remarked by M. Desor that the strata 

 most nearly associated with the flysch in the Alps are rich in 

 echinoderms of the Spatangus family, which have a decidedly 

 tropical aspect." 



Passing back to the Cretaceous period, we find, closely asso- 

 ciated with the floating ice in the sea of the White Chalk, fossil 

 evidence of a warm condition of climate. And then, if we go 

 back to the Permian period, we find glaciers reaching the sea- 

 level in the very centre of England, and other indications of an 

 age of ice, as has been clearly proved by Professor Ramsay. 

 But the fossil remains of the Permian period declare emphati- 

 cally the prevalence of a warm and equable condition of climate 

 also during that age. 



Sir Roderick Murchison has done me the honour to refer, in 

 the last edition of the ' Siluria/ page 548, to my views on the 

 occurrence of glacial epochs during past ages. He is opposed to 

 the opinion held by many geologists and expressed in one of my 

 papers, that there probably was ice-action during the Old-Red- 

 Sandstone and other early periods. Supposing that it were 

 proved that there was no ice during the Palaeozoic age, this would 

 not affect the cosmical theory in the least degree ; for it is quite 

 possible, as has been already shown*, that the direct heat of the 

 * Phil. Mag. S. 4. vol. xxxv. p. 373. 



