THE PKEPARATION OF THE EARTH FOE MAN's ABODE, 85 



three living genera of Crustacea — Serolis, Limulus, and 

 Branchipns — and the trilobites of pakeozoic times, Buckland, 

 in his Bridgeioater Treatise, writes : " When we see the 

 most ancient trik)bites thus placed in immediate contact 

 with our hving Crustaceans, we cannot but recognize them 

 as forming part and parcel of one great system of creation, 

 connected through its whole extent by perfect unity of 

 design, and sustained in its minutest parts by uninterrupted 

 harmonies of organization."* 



The story of the earth has been the subject of many 

 voluminous works, so great is the accumulation of the 

 results of the observations and researches of geologists in 

 many lands. It will be obvious, therefore, that in a single 

 pap^r nothing more can be attempted than a very general 

 summary of the Avonderful story, which can deal only 

 broadly with the great teachings of the records of the 

 rocks. 



These records, clearly, distinctly, and even conspicuously, 

 tell of progression throughout a vast period of time, as the 

 result of agencies of nature working ceaselessly and 

 unchangingly, yet with results differing in magnitude and 

 intensity in different regions and at different epochs, but all 

 the consequence of laws that know no change. Thus, 

 although what is commonly called uniformitarianism in 

 geology has been displaced by the present evolutionary 

 geology, even as uniformitarianism displaced catastrophism 

 ■or convulsionism, every geologist is and must always be a 

 uniformitarian with respect to the ultimate causes of the 

 building up, and of the sculpturing and conditioning of the 

 present surface of the globe. 



Three Periods. 



The existence of this planet may be said to have extended 

 through three periods, the first of which is hypothetical, the 

 ■second consequential, and the third historical, since its 

 history has been written in language both clear and unim- 

 peachable; the universal language of the records of the rocks. 



The First Period saw the aggregation of the matter of 

 the earth ; its fused and intensely heated condition ; its 

 ■assumption of the globular fonn ; its revolution around a 

 great overmastering attracting body, the sun ; its rotation 



* "Geology and Mineraloory considered with reference to Natural 

 Theology" {Bridgea-ater Treatise, vol. i, p. 394). 



