352 Miss I. H. Lowe — Igneous Rocks of AsJtprington. 



facing the Harbourae River. The contour of the ground did not seem 

 to be dependent on the nature of the rocks, and could not be relied 

 upon in tracing the extent of any one type. 



North of the River Harbourae diabase alone is exposed in Austin's 

 Close quarry (XXII) and in several crags in a copse to the south-east 

 (XLI). Eastward of this, in Crowdy's quarry (XXVIII), there is 

 a more varied section, at the base of which fine greenish-grey banded 

 ash is shown, followed by a layer of calcareous ash containing 

 fragments of crinoid stems and casts of brachiopods and corals, and 

 passing up into an impure fossiliferous limestone. Above this is an 

 amygdaloidal lava, succeeded by ashy and concretionary calcareous 

 bands. The beds in this quarry are gently undulating, the axes of 

 the folds running east and west. Similar sections in which ashy 

 and calcareous bands alternate are exposed on the banks of the 

 River Dart; from these, recognizable fossils have been obtained and 

 are described in the Torquay Survey Memoir (p. 81). To the south 

 of the River Harbourae, in a recently opened quarry, which will be 

 referred to as " Xew quarry" (XXIX), the rock is worked from 

 a platform about 50 feet above the level of the entrance. The 

 section exposes at the base much cleaved fine ashy material, forming 

 the walls of the approach to a slide down which the quarried material 

 is shot. Above this a coarser green ash with whitish patches and 

 silvery cleavage surfaces forms the platform, and is succeeded by 

 a dark-green amygdaloidal diabase, which also crops out as crags on 

 the hill above. The dip of these rocks is practically horizontal. 

 To the south, in the same hill, is a quarry (XXIV) largely 

 overgrown, where the rock exposed is diabase, red in colour from 

 long-continued weathering. 



To the south-east of Austin's Close, forming crags in a hedge 

 (XL, XXVII, XXVI), a rock occurs containing large fragments 

 (9 by 4 inches and 10 by 3 inches). The fragments are splintery, 

 subangular, and greyish-white in colour, embedded in a tough green 

 rock. The matrix showed irregular hollows on the weathered 

 surfaces ; these hollows have a distinct linear arrangement, and may 

 represent cavities from which other fragments have been worn. 

 The cleavage planes cross these lines and dip to the south-east at 

 45°; a dip which is very constant throughout the area (Fig. 2). 

 Rocks collected from higher up on the hill (XLII, L, LI) and on 

 the south-east slope of the hill (XXXIII-XXXVI) were not easy 

 to distinguish as either diabase or ash. 



3. Petrological Characters of the Igneous Rocks. 

 (1) Diabases. 

 Throughout the Ashprington district diabase, when freshly 

 exposed, is dark green, tough, compact, and frequently amygda- 

 loidal. The ainygdales often have a linear arrangement, are not 

 more than an inch in length, and are filled with a fine aggregate of 

 chlorite, sometimes associated with epidote. A few of the diabases 

 are slate-grey in colour ; the one from Down's Hill quarry, a quarter 

 of a mile south of Totnes, is an example of this type. It contains 

 exceptionally large banded amygdales several inches in diameter^ 



