Horace B. Woodward — Notes on the Devonian Rochs. 451 
He described the Old Red Sandstone of Cockington as “ ckocolate- 
coloured, micaceous, siliceous, and very compact sandstone.” 
The fact that the Devonian slates and limestones in South Devon , 
as well as in North Devon, are underlaid by beds resembling the 
Old Red Sandstone, is most important. Almost every writer speaks 
of their mineralogical resemblance. So far as I know, the beds at 
Cockington have yielded no organic remains, but I obtained some 
obscure plant-like markings. 
We can draw no such close comparisons between the Devonian 
Slates of South Devon and the Lower Limestone Shales, although 
there are local resemblances. The former beds are, however, much 
affected by cleavage. In West Somerset some of the Devonian 
slatv beds are much like the Lower Limestone Shales of the Mendip 
Hills. 
When we come to the Devonian Limestone, we find a great and 
striking mineralogical resemblance to the Mountain Limestone. Some 
beds are of a dense blue colour, with few veins of calcite ; others 
again are very freely veined with a fine network of spar, or contain 
broad bands of crystalline matter. Beds of nearly white limestone 
occur near Ideford, others again are Oolitic in structure. It may be 
remarked, also, that many of the beds of Devonian Limestone, when 
fractured, emit the same sulphurous smell as does the Mountain 
Limestone ; while the slaty beds beneath sometimes exhibit similar 
alternate bands and nodular beds of limestone. So that almost every 
lithological feature that one may observe in the Mountain Lime- 
stone of the West of England is repeated in the Devonian Limestone 
of Devonshire. This reminds me that a few years ago, when writing 
in conjunction with Mr. Bristow about the much-abused limestone of 
Cannington Park, near Bridgewater, we spoke of its striking re- 
semblance in all particulars to the Mountain Limestone. I can 
only add now that lithologically the Cannington Park Limestone 
is as much like the Devonian as the Mountain Limestone . 1 2 
Sedgwick and Murchison noticed the occurrence of “ thin laminrn 
of bright coal ” in the limestone near Plymouth . 3 Mr. Godwin- 
Austen too observed that “ the limestone of the Ashburton band is 
exceedingly carbonaceous, containing even seams of anthracite,” and 
he detected the same feature at Totnes. He considered the formation 
of the carbonaceous matter to be due to marine rather than to ter- 
restrial Vegetation . 3 
The weathering of the Devonian Limestone is naturally similar 
to that of the Mountain Limestone. Some of the honeycombed 
surfaces that may be seen on joints and exposed edges of the rock 
in a quarry at Wolfsgrove Farm, near Kingsteignton, showed that 
when fossils occurred, they stood out in relief in the cavities, 
proving that liere at least the phenomena resulted from the action of 
atmospheric agents, and not that of snails. 
1 Geol. Mag., Yol. VIII. p. 500. See also Geol. of E. Somerset, etc. (Geol. 
Survey), p. 26. 
2 Trans. Geol. Soc., 2nd series, vol. v. p. 651. 
3 Idem, vol. vi. pp. 461, 469. 
