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APPENDIX C. 
Memoir of the Stratification of the Hackness Hills, 1829." 
[By Wm. Smith.] 
The principal object of the annexed map is a delineation of the 
Geological structure of some of the most irregular ground in England, 
namely, that around Hackness Hall. The valleys of this District, 
with their intermediate ridges of hills, both in form and Geological con- 
struction, may be considered unique. The valleys which unite about 
Rivaulx Abbey have the nearest resemblance, and the various branch- 
ing valleys north of Lockton, which comprise the hole of Hurcomb, are 
also singularly formed ; but the intermediate hills are not composed of 
the same number of strata. Numerous other valleys in the long range 
of the Tabular Hills from Scarborough to Hambelton have no 
resemblance in form, although their Geological construction, generally 
speaking, is the same. Troutdale and Deepdale branch up into the 
moors in singular form, and Dalby Dale above Thornton, extends its 
ramifications by Stones-dale almost to the edge of Cross-clilf , so that the 
district between Newton-dale and Har wood-dale, which is part of the 
Tabular hills, and bounded by the same kind of high contour, has the 
most singular valleys deeply curved into the planes of the Stratification. 
On Knox's excellent map of the vicinity of Scarborough those forms are 
well depicted and may be readily compared. The form of Hackness 
valleys comprised within the high land of Suffield, Silpho, and Broxa, 
which is Geologically insular, may be compared to the branchings of 
a stag's horn. And no one can understand the intricate forms in the 
surface of this ground without traversing the hills as well as the valleys ; 
for on riding along the high side of the elevated plane of Silpho and 
Broxa moors, even the ends of the valleys are not discernible. Such 
is the ground of which we have to show the Geological construction 
composed of insulated parts of some of the most regular strata in the 
British Series. 
The highest edge of Silpho and Broxa moors like that of all the rest 
of the Tabular hills from thence to Hambleton, is composed of Calcar- 
eous Grit, but this is not the highest stratum in the series, as the 
CoralUne Hmestone reposing thereon forms the points of most of the 
hills around Hackness Hall and at Silpho the lower beds of that stratum 
which Mr. Phillips calls the Upper Calcareous Grit, reposes on the 
