GEOLOGY. 307 



Vineyard, and Portland, submergence of the land is proceeding, lo- 

 cally, at the rate of probably four feet in sixty years. In New Bruns- 

 wick, at St. John's, the land has been elevated ; at the Grand Manan 

 Island and the Great Tantaman Marsh, there has been subsidence. 

 At Bathurst, and on the opposite coast of Lower Canada, the land 

 seems to be rising. In Nova Scotia, near the Bay of Fundy and 

 Mines Basin, there is subsidence ; on the southern side, however, 

 there are signs of elevation. The sea rapidly encroaches upon Louis- 

 berg, in Cape Breton ; and in Prince Edward's Island, also, submer- 

 gence of the land is taking place. 



The Swiss Geological Strata in the form of C form the subject of 

 an interesting paper recently published by Professor Strada, of 

 Berne. He expresses the opinion that all the facts considered lead 

 him to recognize an immense lateral force, the action of which has 

 been propagated from the axes of the Central Alps to the borders of 

 the chain. This force does not appear to bs in direct relation to the 

 granitic masses, but is rather due to the origin or enlargement of the 

 crevasses of the earth's crust, by which all the zones of the Swiss 

 Central Alps, composed of serpentine and metaniorphic schist, etc., 

 haA'e been brought to light in the same manner as a button forces the 

 sides of a button-hole when passed through it. 



Rigidity of the Earth. Dr. Joule, in a recent communication to 

 the London Geological Society, in reference to speculations on the 

 thickness of the earth's crust, stated that he had some time ago re- 

 ceived a letter from Professor Thomson, giving an account of the 

 progress of investigations calculated to throw light on this interesting 

 subject. Professor Thomson finds that the equilibrium lunar tide in 

 a solid glass globe, without mutual gravitation, of the same size as 

 the earth, is about five feet. Hence, from the phenomena of the 

 actual tides of the ocean, it follows that the earth, as a whole, is more 

 rigid than glass. The observations of Mallet with experimental 

 earthquakes show that the earth's crust is many times less rigid than 

 glass. Hence Professor Thomson infers that the earth, as a whole, is 

 many times more rigid than the rocks and strata on its surface. 



Divisions of the Earth's Crust. In a recent discussion in the Bos- 

 ton Society of Natural History, Professor Agassiz remarked that in 

 late general works eleven or twelve subdivisions of the earth's crust 

 are given ; D'Orbigny makes twenty-seven ; but he (Agassiz) was pre- 

 pared to show the occurrence of at least forty-eight successive periods 

 of change, with characteristic fossils found neither below nor above 

 their respective beds ; the alleged identity of fossils in different strata 

 was only apparent, and would be found so on actual comparison of 

 specimens. 



In the tertiary, according to Mr. Lyell, four or five per cent, of the 

 eocene species pass on to the present period, nineteen per cent, in 

 the miocene, and about one-half in the pliocene ; this he regarded as 

 an error which would not have been committed with a sound zoolo- 

 gist by his side. He instanced Rostellaria jissurella, which had been 

 considered identical in several formations, as being easily recognized 

 to embrace distinct species on actual comparison of the specimens. 

 He objected to Deshayes's principle of requiring equal and great dif- 

 ferences in the determination of species, as what would constitute a 



