6 PROF. T. G. BONNEY ON THE GEOLOGY 
beneath this mica-schist comes the mass of rock which forms the 
headland of Prawle Point, and is exposed in the grand cliffs for a’ 
considerable distance on either side. This latter rock varies in 
colour from a dull green to a light yellowish (epidote) green. Some- 
times rapidly alternating bands of different tint appear to indicate a 
very distinct bedding, at others it is more massive and homogeneous. 
Generally it has a somewhat decomposed aspect ; in the latter case 
it is often very rotten, passing into a crumbling earthy or sandy 
material, sometimes of a rusty colour, and forming a pitted carious- 
looking surface, the rounded hollows being occasionally several inches 
in diameter and three or fourinchesdeep. It frequently reminded me 
of a rotten ‘‘ greenstone tuff;” and now and then I could have sup- 
posed myself to be looking at a decomposed diabase. In two or 
three places I fancied I detected a slightly fragmental aspect, but 
could never satisfy myself that this was more than an accidental 
resemblance. In other places, however, the banding of the rock is 
very distinct, and it has more the aspect of an ordinary schist, 
though the foliation is seldom or never of a kind that renders it 
conspicuously fissile. Still, though rightly classed among the meta- 
morphic rocks, it may be well to keep in view the possibility of this 
having once been a fine basic tuff. As will presently be seen from 
examination of the microscopic structure, it is rather difficult to give 
this rock a name. We may continue to call it “ chlorite rock,” 
with De la Beche, or adopt ‘ chloritic schist ” as being slightly less 
definite as to its mineral character, remembering that it occasionally 
becomes rather massive. The dip indicated by the banding, which 
I think can only result from bedding, at one place rather to the - 
north-west of the Point, was about 45° towards a point between 
N.N.W. and N.W. At the Signal House it is about 45° or 50° to 
N.W., or even slightly to the west of this. 
The steep cliffs on the eastern side of the Point rendered examina- 
tion difficult ; but, so far as I could see, the general character of the 
rock for about three quarters of a mile is similar to that already 
described. JI then descended to the shore, the chloritice schist con- 
Fig. 2.—Section on shore E. of Prawle Point. 
A,, A,, A,. Bands of Mica-schist. B,, B,. Bands of Chloritic schist.. 
tinuing to form an inland line of crags; the reefs by the water afford 
the section given in the diagram (fig. 2). Three bands of mica- 
