372 Geological Society. 



singularly steril and arid. The white colour of the rock is 

 however only superficial, the recent fracture exhibiting 

 gray, yellow, and brown tints. Jt is distinctly stratified, 

 and rises at a high angle. The texture of this rock is va- 

 rious, from imperfectly conchoidal to loosely granular, 

 composed of rounded grains, and in some beds of angular 

 fragments. It divides naturally into rectangular blocks, on 

 the surface of which is the appearance as if of cylindrical 

 bodies imbedded in the mass, forming a number of circular 

 protuberant spots, of a white colour and more compact 

 tex'.ure than the rest of the rock. A section at right angles 

 to the natural surface of these blocks, shows that the above- 

 mentioned circular spots are occasioned by the cross frac- 

 ture of straight cylindrical bodies, which are perhaps the re- 

 mains of some species of sabella. Associated with this 

 grit are compact gneiss, hornblende slate, and svenitic gra- 

 nite, but their lelative positions Dr. M. was unable to as- 

 certain. Subordinate to and apparently alternating with 

 this grit is a great deposit of limestone in two very thick 

 stratified beds, with a thick kind of grit interposed : in some 

 pans the section of these beds forms a continuous and even 

 line, but in other parts is so curved and broken that the 

 stratificalicn can scarcely be perceived. 



The limestone is a dark gray or nearly black, of an 

 earthy aspect and minute granular fracture, and smelling 

 offensively when rubbed. It does not apj)ear to contain 

 organic remains, but is traversed by veins of red or white 

 calcareous spar. It contains grains of sand, and therefore 

 gives fire with steel. Its surface is covered for the most 

 part with a loose calcareous tufa, which in some places 

 being rendered solid by an infillration of calcareous matter 

 coi>titutes a hard breccia. 



In the same valley of the Tain, of which the above rock 

 forms the precipitous side, occur insulated njasses rising 

 thi)u-h the gross ofunstratified granular marble, varving in 

 coiuur from pure white to gray, the geological relation of 

 wlnf!) Dr. M. has not been ai)Ie to determine. 



Tois is the white mnrble mentioned by Williams in his 

 *' Mniera! Kiuiidom," and which has since been wrought 

 with some succfs^s l)y Mr. Toplin, of Gateshead. 



Miv 21, 1813 — The President in the chair. 

 \\ ilham Hill, Esq. of Bedford row, 

 Hastings Elwin, Esq. of Farnham, Dorset, 

 F.edcrick Daniell, Esq. of Lincoln's Inn Fields, 

 were el cted Members'" of the Society. 



A paper by ttiC Rev. William Gregor, Hon. M.G.S. 



containing 



