446 MR. H. BOLTON ON A MARINE FAUNA IN THE [Nov. I907, 



This exhausts the list, so far as I am aware, of the fauna of the 

 Bristol Coalfield, until in 1905 the Ashton-Vale Coal-and-Iron 

 Company commenced an exploration-branch in their Ashton-Yale 

 Colliery, in search of certain thick coal-seams which were believed 

 to exist underneath the lowest seam then being worked. During 

 the progress of the working, the excavated material was fortunately 

 brought to the surface. The strong similarity of some of the 

 material to certain black shales of the Lower Coal-Measures of 

 Lancashire led me to examine the spoil- heap somewhat closely, 

 a work in which Mr. W. MacPherson, E.G.S., rendered consider- 

 able help. It was not long before evidence of fossils was obtained, 

 Lingula mytiloides and minute gasteropods being fairly plentiful. 

 By the courtesy of the Colliery company I obtained permission to 

 go down the pit, in order to locate the fossiliferous shales. These 

 were eventually found, and their precise position with relation 

 to the ' Eed Ash ' (or ' Little Yein ') and the ' Gays ' seam was 

 determined. Additional material for examination was then ob- 

 tained from the beds in situ ; and afterwards a full series of 

 samples was taken from every bed occurring in the exploration- 

 branch. 1 Scarcely had this been accomplished, when the miners 

 drove forward into heavily-watered sandstones, the yield of water 

 seriously hindering further progress. Finally, some few hours 

 after my last visit, the water burst in, in such quantity as to 

 stop working ; and, as it had become apparent that there was 

 no likelihood of coal being found by further search, the exploration 

 Avas abandoned. Still more recently, the whole of the mine has 

 been closed, the upper seams having been worked out. While the 

 exploration-branch was unsuccessful from a commercial point of 

 view, it was nevertheless of value geologically. There is every 

 reason to believe, as I shall show later, that the branch passed 

 through the lowest beds of the Coal-Measures, and that the water- 

 bearing grits in which it ended belong to the Millstone-Grit Series. 

 The section furnishes the only instance that we know in the Bristol 

 district where the junction of the two has been determined or 

 observed; while, at the same time, it serves to set at rest the 

 belief, long held by practical miners, that there existed thick coals 

 below the Ashton-Yale Series. That the section revealed an 

 abundant and characteristic marine fauna is also a point of con- 

 siderable interest. 



II. The Lower Seams of the Bristol Coal-Measures, and 

 their Relation to the Millstone Grit. 



The complete stratigraphical sequence of this portion of the Coal- 

 Measures being now known, it seems desirable that it should be 

 placed on record. 



1 The allocation of a grant of £5 from the British Association Carbon- 

 iferous Zone Committee allowed of the employment of workmen to collect 

 material, a task which was fortunately accomplished before the water burst in. 



