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XXITI.—GEOLOGICAL NOTES ON THE STRUCTURE OF 
MIDDLE AND NORTH DEVONSHIRE, MADE DURING 
A WALKING TOUR IN DEVONSHIRE IN THE SUM- 
MER OF 1878, sy tHe Rev. Dr. HAUGHTON, F.1.0.p., F.R.s. 
[Read 20th January, 1879.] 
DurinG the course of last summer I had an opportunity of 
visiting in a walking tour those portions of central and northern 
Devonshire with which I was not previously acquainted, and I 
propose to bring under your notice such general results as can be 
obtained by a geologist on such an excursion. 
It has been proposed to explain the structure of the Devonian 
rocks by the aid of a “fault,” but, in my opinion, such an attempt 
is not justifiable, unless very clear evidence is obtained of the 
existence of a “fault.” I visited Devonshire last summer for the 
second time, after an interval of about five and twenty years, and 
believe that its geological structure may be represented, without 
any hypothesis as to a “fault,” in the following manner :— 
The uppermost of the Devonian rocks form a synclinal axis 
half-way between Hartland, Clovelly, Bideford, Appledore, 
Barnstaple, and South Molton on the north, and Tintagel Head, 
Launceston, and Okehampton on the south; on the northern 
and southern edges of the synclinal beds above indicated a broad 
band of calcareous flinty slate and flagstone crops out, which I 
had an opportunity of examining at Okehampton on the south, 
and at Barnstaple on the north. 
On the southern outerop, near Okehampton, the calcareous slate 
beds overlie beds of white and yellow sandstone, and these, in 
their turn, lie upon the granites of Ys Tor, which is the northern 
edge of the granitic outburst of Dartmoor forest. 
The calcareous slates west of Okehampton dip to the north- 
west at an angle of about 35°, but in consequence of their impurity 
have long since ceased to be used as a source of lime for manure, 
as is evidenced by the line of abandoned quarries and limekilns 
along their outcrop. 
On the northern edge of the synclinal beds south of Barnstaple 
I found the same calcareous flinty slate beds as at Okehampton, 
dipping due south, and believe I am justified in regarding the 
whole of the Devonshire rocks between Barnstaple and 
Okehampton as forming an east and west synclinal basin, 
