250 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 16, 



few remarks, as well as on a suite of specimens which Mr. Bruff 

 kindly submitted for examination. 



The well, which is situated near the Pier and a few feet only above 

 the level of the river, was commenced in July 1854, and in May 1857 

 had reached its present great depth. 



Drift 25 ft.- 



Section of the Boring at Harwich. 



1. 2. Feet. 



Earth 10 



Red gravel , 15 



"London clay 23 



Coarse dark gravel 10 



Tertiary Strata 51-| ft. <J S a ^ ti u C f ay "VV j L 



Bluish clay with green sand 3-£ 



Green and red sand intermixed... 5 



Blue clay 3 



Chalk with flints 690 



Chalk without flints 160 



Chalk, rocky, in thin layers 38 



Greensand and Gault 22 



Gault without sand 39 



Black slaty rock 44^ 



Chalk 888 ft. 



Upper Greensand and Gault... 



V 



1070 

 It thus appears that, after passing through the Chalk and finding 

 the Upper Greensand well marked and in regular order, and then the 

 Gault, but in diminished thickness, the workmen came, at a depth of 

 1025 feet, to a mass of strata denoted as a black slaty rock. Un- 

 fortunately this rock, as far as 1 have examined it, contains no fossils ; 

 we have therefore only its mineral and physical characters to guide us. 

 These however are tolerably marked. 



The Upper Greensand is very calcareous and rather argillaceous. 

 The Gault also consisted of the usual calcareous clay ; but the under- 

 lying rock does not effervesce at all with acids. It also has a rough 

 slaty fracture, and becomes harder and of a darker grey in descend- 

 ing. It contains a little mica. Some portions, however, have a more 

 glossy and greenish hue ; but the greater part is a common grey 

 clay-slate. The specimens brought up by the boring-tools consist of 

 round cylinders, about 3 inches in diameter, which break so as to 

 show the lines of bedding or of cleavage, or possibly of both ; for 

 I find that three specimens, from depths of from 1040 to 1060 feet, 

 split at angles respectively of 55°, 53°, and 58 p with the surface, 

 whereas one specimen from a depth of 1066 feet and another of 

 similar character, but without depth mentioned, give angles of about 

 84°. In one of the latter specimens there is also a trace of another 

 divisional plane with a slight variation of mineral character more 

 resembling lines of lamination or bedding ; and, on measuring the 

 angle formed by these two lines in this specimen, I find it to be 

 about 30° : and, as the three specimens higher up give only one 

 divisional plane, which is inclined with an average dip of 55° to the 

 level furnished by a line at right angles to the axis on the vertically 

 bored cylinders, this would seem to show that there is one set of 

 parallel divisional planes throughout, and that there are traces of 



