Vol. S^.'] ORIGIN OF THE PLATEAUS AROUND TORQUAY. 119 



and to observe some facts connected with it which hitherto seem to 

 have escaped attention. 



The geological structure of the Brixham area is comparatively 

 simple, the Devonian rocks occurring in three parallel bands striking 

 from west to east, that is, a broad band of limestone on the north, 

 with an intermediate band of slates and volcanic tuffs, backed on 

 the south by high ground consisting of Lower Devonian grits and 

 sandstones. 



In the immediate vicinity of Brixham the plateau-area is practi- 

 cally limited to the limestone, the highest part of the area being 

 about 220 feet above the sea-level. This plateau is there separated 

 from the higher ground to the south by valleys excavated in the 

 band of slates ; these valleys, however, meet at Brixham, forming 

 a deep ravine which cuts northward through the plateau and 

 terminates in Brixham Harbour. Hence it is evident that the 

 original slope of the ground must have been in a northerly 

 direction. This inference is confirmed by inspection of the ground 

 above Mudstone Bay on the eastern coast, where the slates rise 

 into a hill which is actually higher than the summit-level of the 

 plateau to the north of it : the latter reaching 190 feet, the top of 

 Mudstone Hill 222 feet, and the adjoining land to the south-west 

 rising to over 300 feet. 



The original features of the ground are still more clearly visible 

 to the westward, between Churston and Galmpton, where there is 

 complete continuity between the plateau and the higher ground to 

 the south of it. Here the plateau consists mainly of limestone, but 

 partly of the older slates which dip below it. The average level 

 of the plateau is about 200 feet ; but on the slate-area the ground 

 rises southward from 230 to 378 feet in one-third of a mile, and 

 to 440 feet in the same distance farther south. 



It is clear, therefore, that the original slope of the Brixham and 

 Churston plateau was not southward, like that of St. Marychurch 

 and Torquay, but northward from the high ground of the Lower 

 Devonian grits towards Torbay. Now, if this was so, we ought to 

 find a part of the continuation of the plateau in the country behind 

 the south-western corner of Torbay, and such is actually the case. 



The plateau of the Brixham limestone extends continuously 

 westward over Galmpton Common to Waddeton on the northern 

 side of the Eiver Dart. This surface passes northward onto a tract 

 of ground which consists geologically of a faulted complex of lime- 

 stones, slates, and volcanic tuffs, but which nowhere rises to more 

 than 258 feet and has an average level of about 200 feet. This area 

 extends northward for more than a mile, although it is impossible 

 to fix its original limit near the present coast-line because of 

 Pleistocene detrition and erosion. In the parishes of Galmpton 

 and Goodrington, however, the width of the plateau from north to 

 south is certainly 2 miles. 



Westward this plateau can be traced inland for a distance of 

 more than 3| miles, the land nowhere rising much above 200 feet 

 from the coast to and beyond the village of Stoke Gabriel. Here 



