1820.] ■ Geological Society. 59 



principally of primitive rocks and trap. Among the former are 

 several varieties of granite, and specimens of mica slate, clay 

 slate, and serpentine. Among the latter are some specimens 

 resembling those of the neighbourhood of Edinburgh. A few 

 varieties of sandstone interposed with decomposed felspar are 

 the only secondary rocks of the collection. There is nothing in 

 these specimens indicative of valuable metals, or precious stones, 

 or coal, or any kind of animal or vegetable remains. 



May 19. — A letter from E. Hanmer, Esq. M.G.S. describing 

 the Tottenhoe stone, was read. 



The quarries which supply this stone are situated about two 

 miles from Dunstable, at the north-west frontier of the chalk, 

 between the Roman camp and Dunstable hill. The stone forms 

 a bed of from 15 to 25 feet in thickness, at the bottom of the 

 chalk resting on a grey marl, and dipping slowly to the south- 

 east. It has been long used in building, as appears from the 

 churches and other old buildings in the country. 



One hundred grains of the dried stone were found to contain 

 as follows : 



Carbonate of lime 72 



Silex (in very fine white sand) 21 



Alumina 7 



100 



Part of the paper on the Geology of the Environs of SC 

 Petersburgh, by the Hon. W.T.H.F. Strangways, M.G.S. was 

 read. 



June 2. — A paper *' On the Limestone Veins of Cette near 

 Montpelier, by Dr. Daubeny, M.G.S. was read. 



The calcareous rock of Cette is of a compact kind of stone, 

 of a blueish colour, and tolerably destitute of organic remains, 

 and seems a continuation of the secondary limestone, which 

 reposes on the primitive rocks, the granite and mica slate of the 

 Vivarais, alternating with a sandstone that resembles in its 

 characters and geological relations the old red sandstone of this 

 country. 



It approaches to some varieties of the mountain lime, near 

 Bristol, and, like it, contains insulated masses of a greyish-white 

 flint, which vary in size from the magnitude of a man's foot to 

 that of a filbert. 



This rock is also intersected by irregular masses of a limestone 

 quite different in character; although of various degrees of haa-d- 

 ness, it is never bO compact as the rock which it penetrates ; 

 its colour approaches more or less to a yellow ochre ; and its 

 texture is often distinctly striated. These masses are associated 

 with some very beautiful and distinct stalactites, which, from the 

 imperceptible gradation between them and the limestone to 

 which they adhere, their exact resemblance in colour and struc- 



