24 Mr. W. Pengelly on the Bed Sandstones^ 
it is easy to distinguish Sandstones, Conglomerates and Marls from 
each other at a considerable distance, and to determine the prevalent 
rock in a cliff section by its colours alone. 
Between Livermead and Paignton Sands circular yellowish 
patches, from half an inch to three inches in diameter, occur in the 
red beds. When inspected, each is found to be a section of a 
sphere containing a nucleus of stone, which may be angular, 
sub-angular, or rounded ; sometimes it is a fragment of trap, at 
others limestone which may or may not be fossiliferous. In some 
districts — as at Watcombe, for example — nothing of the kind is seen, 
whilst at Livermead Head and elsewhere they are very numerous ; 
but no where are a.11, or even a majority of, the stones thus 
surrounded. There is no unoccupied space between the nucleus and 
the investment, the latter in all cases fitting the former very closely. 
There does not appear to be anything like a constant ratio between 
the dimensions of the nucleus and those of its environment, since 
large spheres contain large or small nuclei indifferently. 
In the Marls east of Exmouth greenish spheres, of the size of 
those just described, and minute specks are extremely numerous. 
Here, however, nuclei do not constantly, or, perhaps, frequently 
occur ; nor are those which present themselves stones ; they appear to 
differ from the matter surrounding them mainly in colour, which is 
commonly a dull olive green, sometimes approaching to black ; 
indeed most of them have a very dark or black central spot. The 
nucleus sometimes sends a few short, thin, and somewhat widely- 
separated rays into the greenish matter surrounding it. 
The sea does not appear to act with greater or less rapidity on the 
yellowish spheres of the Conglomerates or the greenish ones of the 
Marls than it does on the red rocks in which they respectively occur : 
omitting the nuclei, they neither form protuberances or depressions 
in the general surface of the rock. 
Briefly to recapitulate the different colour phenomena, we have : — 
1st. Rocks exclusively red, as at Dawlish. 
2nd. Interstratified red and light- coloured, or Variegated beds, as at 
the Corbons in Torbay. 
3rd. Blotched beds, in which the prevalent red is, for a Hmited 
extent, exchanged for light colours, as near Paignton harbour. 
4th. Red Conglomerates containing yellow or drab spheres 
surrounding mechanical nuclei, as at Livermead Head. 
5th. Mottled Red Marls containing greenish spheres and specks, 
some of the former surrounding chemical nuclei, as near 
Exmouth. 
It must not be supposed that the rocky fragments in the 
Conglomerate are in themselves red, the colour of the bed is due to 
that of the paste in which the stones are imbedded, and to a film 
of the same hue with which they are coated, which can, in most 
