Eaton's Key. Q% 



evidence of changes and catastrophes, whose history is to be 

 sought in the memorials entombed in the strata themselves. 



We give no opinion regarding the theories of Professor 

 Mitchill, not intending to review the work, but merely to aid, 

 as far as in our power, in drawing the pubhc attention to the 

 interesting subjects about which it is occupied. 



If we have any remark to add, it is, that an adherence to 

 the technical precision with which most rocks are at the pre- 

 sent day described, appears desirable in mineralogical and geo- 

 logical descriptions. When in the valuable additions before 

 us we read of schorl rock, we gain only the idea of a rock con- 

 taining that mineral ; but as it occurs occasionally in several of 

 the primitive rocks, we are at a loss which is intended ; we 

 believe it never forms a rock by itself So with the slate 

 rocks : there are several varieties of them — mica slate, clay 

 slate, greenstone slate, &.c. besides some subdivisions ; and the 

 mere word slate does not always give us the precise idea. 

 But we are aware that, in the present case, it was less in view 

 to go into all the details of geological description, than to give 

 a view of our organized remains and of their supposed origin. 



Art. XII, Notice of Eaton's Index to the Geology of the 

 Northern States, together xoith a Transverse Section of the 

 Catskill Mountain to the Atlantic. 



X HE extensive collection of facts in this little book of fifty- 

 four pages, is creditable to the author's industry and discern- 

 ment: he informs us that he has travelled 1000 miles on foot, 

 while investigating the geology of the district concerning which 

 he has written. This district is certainly interesting, and 

 every attempt to diffuse correct information concerning it, 

 deserves encouragement. Mr. Eaton's account of the regions 

 he has explored, has every mark of verisimilitude ; and we 

 commend his efforts to diffuse geological information, by short 

 courses of lectures, in different towns. In his arrangement of 

 rocks, he has deviated from Werner — has adopted some views 



