22 PALAEOZOIC TIME. [CHAP. II. 



racters and their relations so greatly resemble the Sparag- 

 mite Formation of Scandinavia, that it is impossible to 

 refrain from drawing comparisons between them. The 

 Scandinavian formation, however, includes calcareous and 

 slaty deposits, which are wanting in its Scottish analogue ; " 

 and he points out that as Upper Cambrian fossils have 

 been found at the very top of the Sparagmite series, this 

 fact lends support to the view that the Torridon Sandstones 

 are of Lower Cambrian age. 



2. Geographical Restoration. 



The relations which the Cambrian sediments bear to the 

 underlying Archaean, both in this country and elsewhere, 

 are so remarkable that we are driven to conclude that the 

 physical conditions of the earth's surface at this early 

 period of its history were very different from that which it 

 subsequently acquired. At the commencement of what 

 we call the Cambrian period, the surface of the earth seems 

 to have been extraordinarily rugged and uneven, exhibiting 

 a series of lofty mountain ridges separated by deep troughs 

 and hollows, the bottoms of which were 10,000 or 12,000 

 feet below the summits of the ridges. 



How such inequalities were formed is a difficult question 

 to answer. Were they the result of the mode in which the 

 Archaean rocks were originally formed, or were they partly 

 the result of rain and rivers acting on a newly-formed 

 crust ? The conglomerates and coarse sandstones which are 

 so frequent in the Lower Cambrian series, and the un- 

 weathered state of the felspar grains in the grits, are sug- 

 gestive facts, aud one cannot help thinking that these rocks 

 must have been accumulated with much greater rapidity 

 than could be effected by any modern process of formation. 

 An obvious speculation suggests itself: Are we looking 



