Revieics — QoodchilcVs Age of the Earth. 415 



Conclusion. 

 So far as I have been able to ascertain, no definite paleeontological 

 date has yet been adduced in settlement of the geological age of 

 the Sarawak River limestones, which appear to have been regarded 

 by some authors as Paleozoic. The water-worn varieties especially 

 resemble an ancient formation such as the Devonian coral limestones 

 of Northern Queensland ; and the peculiarities of Heteropora, which 

 remind one so strongly of the various Monticuliporoid structures 

 found in the older rocks, seem to add considerably to this suggestion. 

 But neither the sponge, nor the coral, nor the mollusc can be 

 mistaken for Palaeozoic organisms, and we have in such forms of 

 life evidence of the first character to prove their Mesozoic oi'igin. 

 The example of Alectryonia amor allows us to go still further, for this 

 is a good Middle Oolite species, and without the assistance even of 

 the other structures is sufficient to pi'ove that the deposition of the 

 limestones in question must have taken place during that particular 

 period of Jurassic history. 



12, IE ATI :H] "W" S. 



I.— Some Geological Evidence regarding the Age of the 

 Earth. By J. G. Goodchild, H.M. Geol. Survey, F.G.S., etc. 

 8vo. (Edinburgh: McFarlane & Erskine, 1897.) (Eeprinted 

 from Proc. Roy. Phys. Soc. Edinburgh, vol. xiii, pp. 260-303.) 



THE age of the Earth has to be calculated from the physical and 

 biological changes of which the rocks bear evidence. The 

 author thinks that their value-in-time has to be taken with reference 

 to changes of the same nature now in progress — that is, with normal 

 uniformity of action in general, but allowing for catastrophism 

 in certain cases. Even in rocks formed previously to those that 

 yield definite organic remains, there is clear evidence, says the 

 author, of winds, tides, and currents having acted as they do now. 

 " Even as far back as the commencement of the Cambrian Period 

 the two great geological factors, solar energy and gravitation, appear 

 to have operated then very much as now. To a geologist this 

 merely indicates that the close of what has been termed the 

 ' Astronomical History ' of the Earth terminated many millions of 

 years prior to the Cambrian Period ; and that the Earth must have 

 been in a condition suitable for life through a long period of time 

 when the Archeean rocks were in process of formation." 



In calculating the time required for the Physical Changes that 

 have taken place during the Tertiary Period, Mr. Goodchild refers 

 chiefly to the Hebrides for the basis of some of his calculations with 

 regard to changes in the early part of the Tertiary Period. He 

 regards the climax of the Glacial Period to have been about 20,000 

 years ago ; the excavation of the Hebridean and Scotch valleys 

 required 16,000,000 years, if only at the rate of one foot in 2,000 

 years ; and the growth of the Great Old Skye volcano, presumably 

 once 8,000 feet high, and formed at the rate of about one foot in 300 

 years, took up some 2,400,000 years in the Oligocene Period. In 

 the previous Eocene Period the extensive Nummulitio Limestone 



