330 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



expected discoveries. In Canada and in Newfound- 

 land, we find first, according to the researches of 

 Matthew, the same tracts of the sand-haunting worms 

 or other problematical animals which are already 

 known to us from Scotland and Armorica, and there 

 were, further, traces, somewhat confused indeed, of a 

 Mollusc shell. But the interest of all these observed 

 facts almost vanishes before the astounding revela- 

 tions supplied by the celebrated regions of the 

 canons in Western America. 



Few regions of the globe have a more thrilling 

 interest for a naturalist than the great bare and 

 sterile tablelands which, in the states of Montana, 

 Utah, Wyoming, and Colorado, constitute the 

 successive steppes of the Rocky Mountains to the 

 westward of the vast fertile prairies of the Missouri 

 and the Mississippi. In these tablelands, in strata 

 which have remained almost horizontal since the 

 most distant times in the life of the globe, the 

 rivers are scooped out by gigantic ravines caused 

 by erosion or canyons, sometimes more than a kilo- 

 metre deep, whose steep sides arranged in steps with 

 many-coloured tints, offer to the eyes of the 

 geologist the nearly complete series of sedimentary 

 formations, from the primitive foundation up to the 

 end of Secondary times. 



The pre-Cambrian sediments formed by a mighty 

 accumulation of 3500 metres of sandstone, schists, 

 and limestone play an important part in the struc- 

 ture of the ancient base of the Rocky Mountain table- 

 lands. These layers, resting on the early gneiss, 

 seem to have escaped almost entirely metamorphic 

 action. It is, therefore, not very surprising that 



