THE FARMER'S MAGAZINE. 



25 



from existing fishes ; for tlic details of wliich we 

 must a2:ain refer to the "Old Red Ssandstoue" of 

 TTudi Miller. 



The mezozoic ei-a was that of reptile life. The 

 earliest known remains of the reptile class are 

 found, however, towards the close of the palseozoic 

 strata. During tlie mczozoie era it became enor- 

 mously developed. It eontiuued to flourish up to 

 the close of the cretaceous period, and declined dur- 

 ing that of the tertiaries, till it is represented in the 

 present state of the world only by our crocodiles 

 and aligators — by a few harmless turtles and tor- 

 toises — frogs, lizards, and salamanders; and a some- 

 what extensive group of snakes. We cannot enter 

 into the details of the astonishing variety of reptile 

 life whicli prevailed during the mezozoic epoch — its 

 ichthiosaurs and plesiosaurs — its megalosaurs, 

 iguaiiodons, and pterodactyls. 



Their names, however, tlieir enormous size, and 

 their strange forms must be familiar to our readers, 

 from their figures of them exhibited in the Crystal 

 Palace, at Sydenham, as restoredby Professor Owen. 

 Their fossil skeletons must be equally familiar, from 

 the specimens to be seen in most of our museums. 

 To these, the pits and quarries of Kent, and the ad- 

 joining portiolis of Sussex, have yielded a rich har- 

 vest, as well as of the shells which accompany them 

 in the cretaceous system and the Wealden group. 



The fossil remains yielded in rich profusion by 

 the eocene or older tertiary strata of Kent, prove 

 that at periods recent in the earth's history, but re- 

 mote compared with that of man, the site of Eng- 

 land and the adjoining parts of Europe formed a 

 group of spice islands. Turtles frequented their 

 shores, crocodiles haunted their streams, boas coiled 

 round their trees, and monkeys gambolled among 

 their boughs. The nautilus floated on the waves 

 which bathed their shores, or, when danger impended, 

 scuttled his little bark by opening the valves of its 

 air-cells, and sought refuge in the ocean depths. 



After a long interval, there was a subsequent 

 period, that of the pleistocene, or newest tertiaries, 

 when England formed the western promontory of 

 Europe, and was roamed over by the rhinoceros and 

 vast herds of elephants of a now extinct species, 

 {Eliphas pumigeni/is) which was common then to 

 America and Europe, ranging in the former country 

 from lat. 33.50 to the polar regions, and extending 

 thence through Siberia into Europe. An icy climate 

 and an icy sea advanced over the land, as it slowly 

 subsided. Its mammalian inhabitants migrated to 

 lands beyond the reach of the glacial submergence. 

 The land was re-elevated ; the banished animals re- 

 turned. They inhabited the country for a long 

 period, and then disappeared, we know not how, 

 leaving their remains in pools and hollows on the 

 surface of the land, whei'e they are covered by loam, 

 sand, and gravel, and associated with shells which 

 are exclusively those of the land and fresh water. 

 They differ from the shells contained in the 

 erratic deposits in this — that whereas the 

 latter contain about ten per cent, of species not 

 known in a living state, and are of a more arctic 

 character than those of our present seas, and are all 

 marine, the shells associated with the warp drift are 

 exclusively those of the land and fresh water, and 

 are identical with the group now inhabiting the 



neighbonrhood, with the exception of two or three, 

 which arc unknown or very rare here, but are com- 

 mon in France, while one inhabits the Nile. 



England continued united to the continent by a 

 low and wooded region, covered with forests of oak, 

 fir, birch, and hazel, and frequented by the beaver, 

 the red deer, and those other animals which were 

 common to the forests of England and Germany 

 when Cffisar landed, and found our ancestors in much 

 the same stage of civilization as that in which the 

 New Zealanders were found by Captain Cooke. 



The evidence on which the history of these won- 

 derful changes rests was given in a former article, 

 on the question whether there is any geological 

 evidence of the Deluge. In that article we traced 

 the progress of our knowledge respecting the super- 

 ficial accumulalions, and the proofs afforded by the 

 nature of the organic remains which they cover and 

 contain. To that article, then, we will refer, in proof 

 of a glacial climate having extended, at a very recent 

 geological period, over Europe down to the 45th 

 parallel of latitude, and over America 8 or 10 degrees 

 further south. We also stated our reasons for pre- 

 ferring the term "erratic tertiaries" for these depo- 

 sits, to that of " northerifdrifts," or the more general 

 and vague name of "drifts," which classses together a 

 number of deposits of different origin, and fornied in 

 different portions of a long period, during which the 

 same group of animals lived upon the laud and in 

 the waters. The erratic tertiaries within the lati- 

 tudes above mentioned were contemporaneous with 

 the pleistocene strata of Sicily, which have been 

 raised on Etna to the height of 3,000 feet above the 

 sea, and consist of a thick mass of limestone fre- 

 quently as compact as marble, together with sand- 

 stone and conglomerates, alternating with lava and 

 tufa, the series of deposits having an aggregate tliick- 

 ness of more than one thousand feet. 



In the article before alluded to, we adverted. to a 

 line of transported blocks beyond the limits of the 

 erratic tertiaries, which had been transpoited out- 

 wards from the higher regions of the Alps as a centre. 

 These erratics have travelled northwards into France 

 and Switzerland, eastwards into Austria, and south- 

 wards into Italy. From the lower portions, how- 

 ever, of the Alpine regions, as in Carinthea and 

 Carniola, there are no such indications of transport. 

 It was upon these facts, and the observed effects of 

 glaciers, that Agassiz founded his theory, which at- 

 tributed the formation of the erratic tertiaries in 

 other parts of Europe and America to the action of 

 terrestrial glaciers. He even went so far as to sup- 

 pose that the whole of the regions which are covered 

 with erratic deposits, if not the whole world, 

 were at thia period enveloped in a vast sheet of ice, 

 and that the extinct large mammalia of that 

 period were frozen to death. 



Although this glacial theory of Agassiz is inad- 

 missible as a general explanation of the erratic de- 

 posits, the observations of that able naturalist on the 

 phenomena of the glaciers of the Alps are of great 

 value, as regards their bearing upon questions re- 

 specting the origin of the erratic tertiaries and phe- 

 nomena produced by the action of ice. The polish- 

 ing, grooving, and scratching of rocks, such as is 

 caused by the descent of a glacier down a valley, 

 may be equally! produced by large icebergs, which, 



