(&EOLOGT. 251 



sea did little or nothing in the way of denudation, the principal 

 effect then being the transport of blocks, or the washing about of 

 materials already loose on the surface. — Oeolog. Mag. for May, in 

 Popular Science Review, July, 1866. 



DATE OF THE ENGLISH CHANNEL. 



Mr. Joseph Prestwich, in June, 1865, in a paper before the Geo- 

 logical Society, expressed the opinion that the English Channel 

 was not the result of the last geological change, but that it existed 

 at the time of the formation of the low-level gravels of the Somme 

 and the Thames valleys, and probably at tliat of the high-level 

 gravels. During a recent visit to the raised beach of Sangattee, 

 he found fragments of chert in the shingle and sands, which he 

 believed were derived from the lower cretaceous strata. Associ- 

 ated with them are fragments from the oolitic series of the Boulon- 

 nais, and two pebbles of red granite, probably from Cotentin. From 

 these facts he inferred the existence of a channel 025en to the west, 

 extending between France and England, anterior to the low and 

 perhaps to the high level gravel period. Above the raised beach 

 is a mass of chalk and flint rubble, with beds of loam, twenty to 

 eighty feet thick, and containing land shells. He regarded this 

 accumulation as analogous to the loess, which it i-esemljles in its 

 general character; and the shells found in it belong to species 

 common in that deposit. 



LOUISIANA ROCK-SALT. 



The "New Orleans Times " of a recent date has the following 

 interesting account of the wonderful deposits of salt on Petite Ansa 

 Island : — 



" Perhaps the purest and most important natural deposit of salt in 

 the world is that found on our coast, at Petite Anse Island. This 

 deposit was referred to in French's ' Historical Recollections of 

 Louisiana.' He quotes from the papers left by an English voyager 

 who visited the Mississippi, or as it was then spelt, Mechacebe, in 

 1698-99. 



" Strange as it may appear, all knowledge of this salt mine was 

 lost among our people till after the commencement of the recent 

 war. At that time, the residents of the interior, who were unable 

 to procure a supply of salt otherwise, resorted thither for the pur- 

 pose of boiling down the briny waters which gurgled from the 

 base of the island elevation. This, after some investigation and ex- 

 periments in well-boring, resulted in the discovery of the fact that 

 a great portion of the island, with the exception of an upper layer 

 of earth, was a complete crystal mass of salt. For two years, 

 nearly tlie whole of the trans-Mississippi was supplied from this 

 mine, no less than 21,000,000 pounds being taken from it in the 

 course of three months. 



♦' Borings have extended over a great number of acres, and the 

 salt rock is found everywhere, from fifteen to twenty-two feet be- 

 low the surface. At the point where the principal excavation wa'/ 



