INDUSTRIAL PROGRESS DURING THE YEAR 1872. xxxvii 



Huronian series. Hitchcock, who is carrying on a geologic- 

 al survey of New Hampshire, also adopts this view as the 

 only one consonant with the facts there observed. It may 

 be remarked that the notion of the conversion of great masses 

 of palaeozoic, mesozoic, and even camozoic rocks into series 

 of crystalline schists, which so long found favor both in Eu- 

 rope and in America, is now found to be a hypothesis based 

 on very slender grounds, and that the late researches in the 

 Alps by Favre and others show that it must be abandoned 

 there in its stronghold, as well as in Great Britain and New 

 England. 



In the study of the magnesian limestones of the Permian 

 age in Great Britain, Professor Ramsay has reached the con- 

 clusion that they were deposited in a great inland sea cut oif 

 from the ocean, and that their formation marked a period of 

 evaporation, showing a climatic condition of great dryness. 

 The same conclusion he shows, holds good in the case of oth- 

 er European formations of magnesian limestone. He is thus, 

 he tells us, led to adopt the view put forth in 1859 by Hunt, 

 that dolomites or magnesian limestones necessarily require 

 for their formation isolated evaporating basins, from which, 

 by special chemical reactions, which he has studied, the mag- 

 nesian carbonate is deposited. This view, as the latter has 

 shown, corresponds to the physical and paleontological his- 

 tory of our great magnesian limestone regions in the palaso- 

 zoic area of North America. 



Great progress has been made in the investigation of the 

 fauna of the more recent geological formations in the west- 

 ern portions of the-Contincnt, but the discussion of these be- 

 longs rather to paleontology. 



In Geological Dynamics, Mallet has made an important 

 contribution in establishing, by experiment, the amount of 

 heat developed in the crushing of the strata which must at- 

 tend the great movements producing corrugation in the 

 earth's crust. This source of heat had already been pointed 

 out by Vose, but the researches of Mallet give to it a quan- 

 titative value. He endeavors to show that the amount of 

 heat thus generated as a result of the contraction of the en- 

 velop around a cooling nucleus is more than sufficient to 

 account for that manifested in volcanic phenomena. Mallet 

 adopts the view, now generally received, of a solid rather 



