HARD WICKE ' S S CIE NCE - G O SSIP. 



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his appearance in Europe 3000 or 4000 years B.C., 

 but may have existed for a long time previously in 

 the east, as in Egypt and Asia Minor civilised 

 communities and large States flourished at an earlier 

 date than 4000 B.C. 



In the discussion which followed, the President 

 said the paper was calculated to arouse an animated 

 discussion. Professor Prestwich had only noticed the 

 geological objections to Dr. Croll's hypothesis. The 

 investigations of the Danish geologists in Greenland 

 afforded valuable new data. One most important 

 point for consideration was the age of the valley- 

 gravels in England and Northern France, which 

 Professor Prestwich had so ably treated. 



Dr. Evans regretted that he had to differ from the 

 author, and commented on the boldness of giving 

 numerical estimates of geological time. It was 

 questionable whether the astronomical calculations 

 were quite complete. Considering the deposits 

 formed since the Glacial epoch, both marine and 

 fluviatile, he doubted whether the dates assigned by 

 the author sufficed. Increased rainfall might account 

 for some of the denudation, but the amount could not 

 have been immensely excessive or animal life would 

 have suffered more than it did. Marine erosion told 

 a similar story to fluviatile, as in the case of the 

 southern part of what must have been the old valley 

 of the Solent, which must surely have required more 

 than 10,000 or 12,000 years to remove. Still the 

 ordinary views of extent of time might be exaggerated. 

 The speaker could not accept as conclusive the 

 evidence of the pre-glacial age of man in Wales, and 

 was very doubtful whether the palaeolithic implements 

 found by Mr. Skertchly were in beds of glacial date. 

 Some of the palaeolithic implements in the Eastern 

 districts were made from pebbles brought into the 

 country by glacial action, and it was incredible that 

 any implements of really pre-glacial age should be of 

 the same type. Pre-glacial man might, however, 

 have lived in other parts of the world. 



Dr. Geikie remarked that Sir \V. Thomson origin- 

 ally had allowed 100 millions of years geological time, 

 and it was on this view that Dr. Croll's views were 

 founded. Now, however. Dr. Thomson had limited 

 geological time to about 12,000,000 years. The 

 speaker doubted whether this could have sufficed for 

 the known course of geological events. He wished 

 to know the data on which Professor Prestwich's esti- 

 mates of time were founded. It had been suggested 

 that the upper valley-gravels might be due to the 

 melting of the ice-sheets and not to rivers at all. 



Professor Boyd Dawkins also questioned the figures. 

 There are no standards for measuring time in terms 

 of years outside history, in which not only the 

 sequence of events is recorded, but the length of the 

 intervals between them. In geological time we are 

 dealing with a sequence of events separated from one 

 another by intervals, of neither of which have we any 

 certain measure. Dr. Croll's theory is based on the 



assumption that the Glacial climate was produced by 

 a change in the relation of the earth to the sun. 

 There is no evidence of this. Nor are natural chro- 

 nometers to be found in the variable rate of valley- 

 erosion, or of the deposit of alluvium, or of the 

 retrocession of waterfalls. Nor do Sir W. Thomson's 

 varying estimates of past time (ranging from twelve 

 to three hundred millions of years) help us. The 

 antiquity of man can only be measured by the changes 

 which have taken place in geography, in climate, and 

 in fauna, which have been very great. The strata 

 with palaeolithic implements in Algiers, Egypt, 

 Palestine, and the Dekkan have not as yet been 

 brought into relation with the Glacial Period. 



Dr. Hicks remarked that Professor Prestwich, in 

 giving reduced estimates of geological time, must 

 have been desirous of converting some who seemed 

 still unwilling to accept the evidence obtained, 

 bearing on the pre-glacial age of man, apparently 

 mainly because of the exaggerated amount of time 

 given to the Glacial period by some authors. The 

 evidence as to rapidity of motion of ice in Greenland 

 tended to shorten the necessary duration of the 

 Glacial period. He invited Dr. Evans and all 

 Fellows to be present at the new excavations in 

 Wales, which were to be commenced on June 6th. 

 He described the situation in which the remains ot 

 man, claimed to be of Glacial age, and probably 

 Pre-glacial, had been found, and explained the line of 

 investigation about to be adopted. 



Mr. J. Allen Brown, after thanking Professor 

 Prestwich and Dr. Evans for their contributions to 

 the discussion of this question, proceeded to notice 

 the results of his own researches in the Thames 

 Valley, and especially in the neighbourhood of 

 Ealing, which indicated, he thought, that a lapse of 

 time incalculably vast must have been required for 

 their production. 



Mr. Tiddeman said that the evidence as to the 

 rapidity of motion of the Greenland ice-sheet was 

 most important. He did not think we could safely 

 take the erosion of the limestone around the perched 

 Norber boulders as a measure of the time elapsed 

 since the ice-sheet, because much glacial rubbish may 

 have been removed before the surface of the rock was 

 exposed to weather. The implement adduced by 

 Dr. Evans as proving that palaeolithic man was post- 

 glacial in England could not prove that he was later 

 than z'w&rglacial times ; and of an interglacial land- 

 period in England there were the clearest possible 

 proofs. 



Mr. Topley referred to the relative condition of 

 land now and fifteen hundred years ago, which, he 

 thought, must be of consequence in this discussion. 

 From the remains of Roman works we might safely 

 conclude that the physical condition of the country 

 was practically unchanged since that date ; the fords 

 of the Roman roads are often still in use, and no 

 appreciable amount of valley-erosion has taken place 



