76 Notices of 3Iemoirs — Gu'p'py^s Visit to Dominica. 



Martinique and Guadeloupe, Dominica, like them, is a mass of moun- 

 tains of volcanic structure. There is little that can be called level 

 land, save the alluvial flats of the larger river valleys. The spurs 

 of the mountains usually come down to the sea, often ending in high 

 cliffs and precipitous headlands. 



Immediately at the back of the town of Eoseau, the capital of the 

 island, there is a hill called Morne Bruce, composed of volcanic rocks, 

 upon which lies a marine formation, which seems to have been part 

 of an immense fringing reef, which existed when the island was at a 

 lower level by some 300 feet. This eoral formation is overlain by 

 more recent volcanic accumulations. 



Craters do not seem to occur on the higher mountains, but small 

 volcanic cones, often very perfect, exist on the lower ridges. Most 

 of the rocks are varieties of trachyte. 



Sulphur springs are a common feature all over the island, having 

 mostly a high temperature, ^approaching the boiling point. 



The structure of Dominica seems to show that two distinct periods 

 of great volcanic activity occurred, in the interval between which 

 the land was much depressed, and coral reefs were formed upon the 

 previous volcanic accumulations. The species of corals determined 

 are: Favia ananas, F. coarctata, and Eusmilia aspera ; there are, how- 

 ever, many others, whose specific names cannot be stated with confi- 

 dence. Mr. Guppy gives also a list of twenty-two species of Mollusca 

 from the same formation, which is stated to be of Pliocene age. 



III. — The Geognosy of the Appalachians and the Oki&in of 

 Crystalline Eogks.^ 



By T. Sterkt Hunt, LL.D. 



THE twentieth meeting of the American Association for the 

 Advancement of Science was held at Indianapolis, on the 16th 

 of August, 1871. On this occasion, the retiring President, Dr. Hunt, 

 as is customary, delivered an address, of which the subject chosen 

 was the history of the great Appalachian mountain chain. He re- 

 marks that nowhere else in the world has a mountain system of such 

 geographical extent been studied by such a number of zealous and 

 learned investigators, and no other has furnished such vast and im- 

 portant results to geological science. 



Dr. Hunt first brings forward certain facts in the history of the 

 physical structure, the mineralogy, and the palasontology of the 

 Appalachians; and, in the second place, discusses the conditions 

 which have presided over the formation of the ancient crystalline 

 rocks that make up so large a portion of this great eastern mountain 

 system. 



A section across northern New York, from Ogdensburg, on the St. 

 Lawrence, to Portland, in Maine, shows the existence of three dis- 

 tinct regions of different ciystalline schists. These are — (1). The 

 Adirondacks, to the west of Lake Champlain ; (2). The Green Moun- 



1 Printed in advance from the Association number of the American Naturalist.- 

 8vo. Salem, 1871. 



