REFERENCE TO THE ANTIQUITY OF MAN. 



409 



doubted whether this could have sufficed for the known course of 

 geological events. He wished to know the data on which Prof. 

 Prestwich's estimates 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. 



Prof. 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 chronometers 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 mil- 

 lions 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 paleo- 

 lithic implements in Algiers, Egypt, Palestine, and the Dekhanhave 

 not as yet been brought into relation with the Glacial period. 



Dr. Hicks remarked that Prof. Prestwich, in giving reduced esti- 

 mates of geological time, must have been desirous of converting some 

 who seemed still unwilling to accept the evidence obtained, bearing 

 on the preglacial 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 ex- 

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

 He described the situation in which the remains of man, claimed 

 to be of Glacial age and probably Preglacial, had been found, and 

 explained the line of investigation about to be adopted. 



Mr. De Rance stated that he fully agreed with Dr. Hicks in 

 his interpretation of the facts observed by him. 



Mr. J. Allen Brown, after thanking Prof. 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 re- 

 quired for the production of the observed phenomena. 



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 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 ad- 

 duced by Dr. Evans as proving that paleolithic man was postglacial 

 in England could not prove that he was later than m^rglacial 



