INDUSTRIAL PROGRESS DURING THE YEAR 1874. l x i x 



lowed by about the same amount of a brown sandstone with 

 cretaceous fossils, and by 500 feet of yellow limestone, with a 

 well-marked cretaceous fauna. Beneath the red sandstone, 

 in one locality, is seen a sandstone described as metamorphic, 

 resting directly on micaceous gneiss. 



Hitchcock, continuing his geological survey in New Hamp- 

 shire, has proposed several subdivisions in the crystalline 

 rocks of that region. Of these, he compares the older gneiss- 

 es to the Laurentian, while the strata which he at one time 

 called the altered Quebec group, after Logan, which were re- 

 ferred by Hunt to the Huronian, Hitchcock now considers to 

 be of that age, but makes of them two subdivisions. We 

 look for further details as to these older rocks. Meanwhile 

 he has found in three localities limestones containing corals, 

 crinoidal stems, and a Pentamerus, which belong to the sum- 

 mit of the Silurian or the base of the Devonian, and are 

 therefore, in the nomenclature of the New York Survey, either 

 Lower or Upper Helderberg. They are, according to him, 

 associated with several thousand feet of sandstones, shales, 

 and limestones, in part crystalline, which are believed to be 

 of the same asre. The difficulties in the studv of these rocks 

 are increased by the fact that, according to Hitchcock, the 

 strata are so disturbed "that inversion is the rule rather 

 than the exception." The fossiliferous limestones are of the 

 same period as those found farther northward in the prov- 

 ince of Quebec, and southward at Bernardston, in Massachu- 

 setts, from the study of which latter Dana concludes that the 

 associated mica-slate series is also of Helderber arre. 



The question with regard to the age of the lignites and 

 plant-beds of the West, considered as cretaceous or tertiary, 

 is much debated. It is evident that we had a great Mediter- 

 ranean sea in the cretaceous time, extending from the Gulf 

 of Mexico perhaps to the Arctic Ocean, in some parts depos- 

 iting limestones with organic remains like those of the En- 

 glish chalk. With the drying up of this sea, dependent upon 

 continental elevation, there were deposited great beds of est- 

 uary and fresh-water deposits, with lignites. But the strata 

 which, on the evidence of the fossil flora, are regarded as ter- 

 tiary contain the remains of a fauna which is looked upon as 

 cretaceous. 



Dawson, from a survey of the facts in the case, believes 



4 



