116 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 7, 



with red shale. The conglomerate is chiefly composed of fragments 

 of red granite and quartz pebbles, cemented together in a base of 

 ferruginous red clay. Its thickness has not been ascertained. 



The next member of the group (2) consists of alternating beds of 

 limestone, red and brown shales, and friable micaceous sandstones. 

 No beds of gypsum are visible in this section ; it is only in the neigh- 

 bourhood of the protruded masses of granite and trap that gypsum 

 is met with. The total thickness of this series is 820 feet. Fossils 

 are rare and of few species ; the most common are Producta Lyelli, 

 P. sjnnosa, P. Martini, P. Scotica, Spirifer glaber ; and a few un- 

 detemiined scales of fishes, in one of the upper limestone beds. Some 

 of the shales are finely laminated and rippled. Stigmariae, apparently 

 drifted, as no rootlets are attached to them, occm- in a bed of arena- 

 ceous shale in the higher part of the section. 



The sandstone deposit (3), which is analogous in position to the 

 millstone grit of the English coal-fields, is 1800 feet in thickness. 

 The lower beds are coarse and pebbly ; the upper, fine-grained, and 

 often flaggy, containing impressions of Sigillariae, Calamites, and 

 Lepidodendra. A few thin beds of grey shale are interstratified with 

 the sandstones at wide intervals. 



The productive coal-measures (4) cover an area of 250 square 

 miles, but owing to several extensive dislocations it is impossible to 

 ascertain their total thickness with any degree of accuracy ; from the 

 best information in my possession I conclude that it exceeds 10,000 

 feet. We have one continuous section on the north shore of Boular- 

 drie Island 5400 feet in thickness, and in the middle portion of the 

 field, several detached sections varjdng from 1000 to 2000 feet in 

 thickness, whose exact relative positions have not yet been deter- 

 mined, although it is quite clear that they are higher up in the forma- 

 tion than the highest beds of the Boulardrie section. These points 

 can only be ascertained by a careful survey of the whole district ; I 

 therefore propose, as I said before, to confine my observations at pre- 

 sent to the small portion exhibited in the clifF on the north-west shore 

 of Sydney Harbour. 



The coal-measures commence at Stubbord's Point, where they re- 

 pose conformably upon the millstone grit, and terminate at Cranberry 

 Head on the sea-shore ; the total length of the section being 5000 

 yards, and the thickness from actual measurements, taken at right 

 angles to the plane of stratification, 1860 feet. The dip is north 

 60° E. at an angle of 7°. 



In the following table the beds are placed in their natural order, 

 No. 367 being the highest bed at Cranberry Head, and No. 1 the 

 lowest, in contact with the millstone grit at Stubbord's Point. 



Section of the Coal-Measures on the north-west shore of Sydney 

 Harhoiir, in the descending order. 



No. ft. in. 



367. Slaty sandstone 10 



366. Soft' blue argillaceous shale 6 



365. Argillaceous shale containing a few snaall nodules of iron- 

 stone near the bottom (plants) 4 



364. Argillaceous shale (plants) 2 



