UPPER SHALE. 57 



been ascertained by boring- through the chalk. In 1818 and 1819, 

 Mr. George Rivis of Sherburn bored for coal in a deep dale about a 

 mile and a half south from Staxton. The boring was continued to 

 the depth of 114 yards; and after passing through the white chalk, 

 and the red and grey chalk, the borers came to the blue shale or 

 clay, at the depth of 9Q yards from the mouth of the bore; so that 

 the boring for the last 18 yards was entirely in the clay. Specimens 

 of the shale, and of the red and grey chalk, taken from the bore, 

 were received by the authors from Mr. Rivis. Some beautiftd crys- 

 tals of pyrites were found in the grey chalk, as at the Speeton clifts. 

 According to the statement of the borers, a small seam of bitumin- 

 ous inflammable shale was pierced through at the depth of five yards 

 and a half from the surface, and at some distance below, a small 

 seam of excellent coal : but as no such seams are observed in the 

 chalk cliffs, nor any where else in the chalk strata, as far as we have 

 heard, there is great reason to suspect, that the proprietor has been 

 imposed on, to encourage him to persevere in his fruitless search; 

 and that the bituminous shale and coal, if extracted from the bore, 

 were previously throAvn into it. 



The thickness of the chalk on the heights of the Wolds near 

 this boring, must be very considerable, as it was found in this deep 

 dale to descend below the surface 96 yards, or near 300 feet. How- 

 much of this depth is occupied by the coloured chalk, the authors did 

 not exactly learn, except that, as at Speeton, its thickness bears but 

 a small proportion to that of the Avhite chalk above it. Indeed, as 

 the white chalk appears to pass gradually into the grey, it is difficult 

 to fix the precise limits of each. 



In proceeding westward from Staxton, behind the Wolds, we 

 have access to examine the shale, as at Speeton, Avithout the aid of 

 borers ; for, the chalk rising to a great height, the shale rises along 

 with it, and crops out from beneath it. At Knapton it is foimd on 



p 



