204 THE CANADIAN NATURALIST. [June 



formable to the present surface of the country. This structure, 

 which I conceive to have been superinduced by superficial changes of 

 temperature, is often quite independent of the bedding, as may 

 be seen in the quarries near Augusta in Maine, and in the cuttings 

 on the Grand Trunk Railway near Berlin Falls, New Hampshire. 

 It is also observed in exotic or intrusive granites, like those of 

 Biddeford, Maine. This is, in fact, the concentric lamination of 

 granite, long since observed by Yon Buch, and, I believe, correct- 

 ly explained by Prof. N. S. Shaler to be due to movements of 

 contraction and expansion in the mass, caused by variation of 

 temperature during the changes of the seasons. He has not 

 however observed this structre at greater depths than from three 

 to five feet, while in some rocks I have found it penetrating prob- 

 ably twenty feet. (See Shaler's paper, read before the Boston 

 Nat. History Society, Feb. 3, 1869, and published in the Proceed- 

 ings of the Society, vol. xii, page 289). 



While however I admit the existence in the Dominion of 

 Canada and in eastern New England, of a great series of crys- 

 talline schists, distinct from' the Laurentian, and apparently the 

 same with those found by| Mr. Murray between the Laurentian 

 and the Quebec group in Newfoundland, it is not less certain 

 that we have in these regions rocks of Upper Silurian and Lower 

 Devonian age, holding the characteristic fossils. These strata in 

 Maine and New Brunswick are generally but little altered. In 

 the Connecticut valley at Bernardston, Massachusetts, near Lake 

 Memphremagog in Vermont, and further northward in the 

 province of Quebec, fossils of this horizon are found in rocks 

 which in some localities, are more or less altered and crystalline. 

 I believe however that much of the calcareous mica-slate of 

 eastern Vermont will be found to belong to the Terranovan series. 

 The extent of these newer rocks, and the limits between them 

 and the more ancient schists, of the ruins of which they are prob- 

 ably in part composed, remain problems for farther investigation. 

 For the solution of these Prof. C. H. Hitchcock, by his labours 

 ill Vermont, is already well prepared, and it cannot be doubt- 

 ed that he, with his able assistants, will in the Survey of New 

 Hampshire, now in progress, throw much light on New England 

 geology. It is worthy of remark, that strata holding fossils of Lower 

 Helderberg age, or thereabouts, are not confined to the shores of 

 Maine and New Brunswick, and the vallevs of the Connecticut 

 and St. John rivers, but are found beyond the Green Mountains? 



