89 



Robert Young, Esq., C.E., then gave some 



NOTES ON THE GEOLOGY OF THE EXCAVATIONS 



FOR THE MAIN DRAINAGE WORKS. 



Mr. Young said : — Whilst the high level sewer was being 

 constructed lately, several interesting sections were exposed. 

 At North Queen Street it passed through a very wide basaltic 

 dyke striking nearly north and south, and at the crossing of the 

 Carrickfergus Road the junction of the estuarine bed with the 

 glacial contour of the land was well exposed. The most in- 

 teresting geological fact, however, which came under my notice 

 was at a point in Millfield where the invert of the six foot diameter 

 sewer was 28 feet under the street level, and where for some 

 considerable distance the tunnel was driven through a bed of 

 coarse clean gravel, whilst at each side it had been carried 

 through the ordinary glacial clay overlying the sandstone which 

 is the bedrock of the district. A short time after this, I passed 

 what seemed to be identically the same gravel being lifted from 

 the foundations of the new quay above the Queen's Bridge, 

 which would be about four feet lower than the gravel bed at 

 Millfield where crossed by the bottom of the sewer. In a hasty 

 examination of this gravel from the Lagan bed, I picked up a 

 wrought and rolled flint. 



Mr. Gray said : — Allow me to emphasize what Mr. Young 

 has said with regard to keeping a record of well boring. It was 

 one of the subjects impressed by the British Association upon 

 the representatives of this Society at the last meeting at Leeds. 

 Mr. Young has brought forward and given the result of his own 

 observations, and I am sure we are indebted to him for his very 

 interesting remarks upon this subject. It should be generally 

 known that such records are of the highest value towards the 

 scientific investigation of the sources of water supply. 



