28 Reviews — Whitney and Wadsworth's Azoic Si/stem. 



are a few blanks that require further study, or have been left for 

 various reasons. The work on the other four sheets is of so scattered 

 a nature at present that it was not thought advisable to exhibit them 

 till in a more complete state. 



Besides the actual mapping, a large amount of notes of a descrip- 

 tive character have been collected, and all the important features 

 and sections photographed on a large scale. Specimens of the 

 various lavas, ejected blocks, tufas, pumices, etc., have been care- 

 fully selected as the work went on, so that the author has now in 

 his possession by far the most complete geological collection from 

 the mountain yet extant, and which are open to the study of any one 

 who should care to investigate them. 



I^ IE ATI :e -w" s. 



I. — The Azoic System and its proposed Subdivisions. By J. D, 

 Whitney and M. E. Wadsworth. (Bulletin of the Museum of 

 Comparative Zoology, at Harvard College, Geological Series, 

 Vol. I.) 



THOSE who have read Dr. Sterry Hunt's " Special Eeport on the 

 Tra23 Dykes and Azoic Eocks of South-eastern Pennsylvania," 

 which is in fact a resume of the evidence on Dr. Hunt's side of the 

 Archsean controversy', will be interested in the book before us. Prof. 

 Whitney and Dr. Wadsworth renounce Dr. Sterry Hunt and all his 

 works. They present the case against him with fullness and force. 

 They regard most of his chief conclusions as either unsubstantial 

 dreams or pernicious heresies. They are, in truth, as thoroughgoing 

 in their condemnation of the modern views on Archaean Geology as 

 Dr. Hunt is in their support. Dr. Hunt's boldness in creating hypo- 

 theses seems to have driven our authors into the extreme of scientific 

 scepticism. This reaction is not altogether unnatural. Those who 

 desire to take an impartial view of the Archaean controversy will 

 anticipate that, from the strong antagonism of the disputants, there 

 may arise a searching inquiry into the grounds on which their con- 

 clusions are based. 



Dr. Hunt claims that he and his co-workers have established the 

 existence of seven distinct terranes amongst the rocks which underlie 

 the Cambrian. These, taken in ascending order, are as follows : — 

 I. Laurentian. 

 II. NciKiAN or Labradorian. 

 III. Arvonian. 



IV. Huronfan; the altered Quebec group of Logan. 

 V. MoNTALBAN or Mica-schist series. 

 VI. Taconian ; the Lower Taconic of Emmons. 



VII. Keweenian ; the Copper-bearing series of Lake Superior. Dr. Hunt is not 



certain that this group may not be roughly contemporaneous with the 



Taconian. 



This list is an imposing one, and, if it represents the facts of nature, 



the range of Archaean time may well compare with that of the entire 



P.il^ozoic series, and the study of these ancient rocks becomes one 



of the first importance. 



