

No. I] GEOGNOSTICAL OBSERVATIONS. 537 



Fourth, The secondary limestone appears generally to belong to the vast 

 deposite which lies above the new red sandstone and under chalk, and which 

 is known to form very extensive tracts of country, not only in other quarters of 

 North America, but also on the continent of Europe and in England. Some of 

 the varieties may, on more minute examination, prove to belong to the mountain 

 limestone of geologists. 



Fifth, The secondary trap and porphyry rocks, which occur so abundantly 

 on the coast of the Arctic Sea, and throughout the whole extent of the Copper 

 Mountains, are to all appearance connected with the new red sandstone. The 

 frequency of native copper in those rocks, both on the Copper Mountains and 

 on the sea-coast, is a very interesting feature in their composition, and deserves 

 the particular consideration of those who make the grouping or associations of 

 simple minerals objects of attention. Many of these trap and porphyry rocks 

 presented the columnar structure which has been considered as indicative of a 

 volcanic origin, but their other characters and the horizontal strata upon which 

 they reposed seemed to give them a still greater claim to Neptunian origin. 

 Our opportunities of observation, however, were much too limited to permit us 

 to offer a decided opinion upon this disputed point. 



Alluvial Deposites. — The extensive formation of these deposites in the line 

 of our journey, afforded us numerous examples of their different kinds. In the 

 preceding notes, we have alluded to extensive alluvial formations, occasioned 

 by lakes which have either gradually dried up, or have burst suddenly and left 

 their concavities more or less deeply covered with sand, gravel, and other alluvial 

 matters. Other kinds have evidently had their origin from the action of rivers. 

 Some formations on the sea-coast were occasioned by the conjoined action of 

 the sea, and the wasting influence of the weather. The peninsula, between 

 Point Turnagain and Melville Sound, is almost entirely composed of a low flat 

 of this kind, a few trap cliffs appearing at considerable distances only. The 

 general wasting influence of the weather on the more elevated exposed rocks 

 throughout the country, has formed a covering of alluvial matter of greater or 

 less depth to the subjacent rocks, which protects them from the further gnawing 

 effects of the atmosphere. 



With regard to the large rolled blocks which are so plentifully scattered 

 over the surface of some countries, and which have been considered to have 

 been deposited by the waters of the flood, we have no remarks of moment to 



sz 



