106 Dr. J. Croll on the Physical Theory 



relation to the land than it does at the present time. To this 

 circumstance alone no great importance can be attached; but, 

 when we consider in addition that submergence has almost 

 invariably accompanied glaciation, we may regard it as 

 highly probable that the submergence at the period in ques- 

 tion was the result of a greater amount of ice on the northern 

 hemisphere and a less amount on the southern, than now. 

 This probability is further increased by the fact that during 

 the growth of the ancient Forest, which immediately under- 

 lies the Carse-clays, and indicates a condition of climate even 

 more warm and equable than the present *, the sea stood 

 not only higher in relation to the land than it did during the 

 time of the deposition of the Carse-clays, but somewhat 

 higher than it does at present. The buried Forest doubtless 

 belongs to the period 10,000 or 12,000 years prior to that of 

 the Carse-clayst, when the winter solstice was in perihelion; 

 and at this time, owing to a somewhat greater amount of 

 eccentricity than at present, the quantity of ice on the southern 

 hemisphere might be expected to be greater, and that on the 

 northern less, than now. 



Thus when the northern winters were last in aphelion there 

 was a rise of sea-level, resulting doubtless from a preponde- 

 rance of ice on the northern hemisphere; but when the buried 

 Forest flourished, 10,000 or 12,000 years prior, the winters 

 were in perihelion, and there was a fall of sea-level, due in all 

 likelihood to the preponderance of ice on the southern hemi- 

 sphere. But this is not all : the strata which underlie the 

 buried Forest bear witness to another rise of sea-level. 



These changes of climatic conditions and oscillations of sea- 

 level, which took place during the latter part of the Postglacial 

 period, are just w r hat should have taken place on the suppo- 

 sition that they were the result of those astronomical and 

 physical agents which we have been considering. Thus, 

 immediately preceding the Present period we have that of the 

 25- and 40-feet J raised beaches and the Carse deposits, which 

 indicate that the climate was then more severe and the sea 

 somewhat colder and standing at a higher level than at 

 present. Now during this Eecent period our northern winter 



* Those who doubt the equable and warmer character of the climate of 

 the submarine Forest-bed period should study the mass of evidence on 

 this point given in 'Prehistoric Europe.' 



t For the probable dates of the Carse-clays and the submarine Forest- 

 beds see Appendix. 



X At one time I thought (/ Climate and Time/ p. 409) that the 40-feet 

 beach might belong to a period 50,000 years prior to the Carse-clays ; but 

 I am now satisfied that the two beaches both belong to the period of the 

 Carse-clays, as Prof. J. Geikie has shown. 



