160 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 8, 



and Dunrobin, the relations of the great series of estuarine beds to 

 the Liassic rocks cannot be seen. 



In order to illustrate the variations in the thickness and order of 

 succession of these estuarine strata, I subjoin a number of sections 

 obtained by shafts and borings at various points, beginning in every 

 case with the " Boof-bed " — that is, the lowest bed (marine) of the 

 Middle Oolite (see fig. 15). 



Fig. 15. — Comparative vertical Sections of the Coal-bearing Strata of 

 Lower Oolite age in Sutherland and Ross. (Scale 20 ft. to 1 in.) 



Doll. 



"Roof-bed of Coal" (equiva-j EiJigiiiJ 

 lent of Kelloway Rook) j I ^^~rj 



{ 



Fascally. Inverbrora. 



Cadh'-an- 



Main seam of Coal 



Highly carbonaceous shales 

 with thinner seams of Coal 

 (very variable) 



Fire-clays with shelly bands, 

 bone-beds, &c '•. 



Clays (greenish, whitish, and 

 black) with bands and no- 

 dules of argillaceous lime--{ 

 stone and occasional thin 

 coal-seams 



Sandstones below. 



(1) Boring on shore at Inverbrora by John Pritchard, 1811 : — 



ft. in. 



"Roof bed" 4 



Blue bind 3 6 



