BONNE Y : ON THE ORIGIN OF THE BRITISH TRIAS. 11 
So we can hardly be wrong in claiming the Bunter as a 
fluviatile deposit. But some of those, who admit this, deny, 
for the reasons indicated above, that the river or rivers which 
brought the materials to the Midlands came from the north. 
The pebbles, as I have more than once pointed out, must have 
had a long journey, and could only have been transported by 
a strong stream — not less than that of the Rhone between 
Martigny and the Lake of Geneva. Volume and velocity demand 
that such a stream should have been fed by a mountain region.* 
Were such a region buried under the post-Triassic Mesozoic 
deposits in the south-eastern half of England, it must have 
disappeared with remarkable celerity. Hills there may have 
been in this direction, but the Lickey and Clent ridges, and the 
rugged Charnwood upland, besides being composed, with rather 
rare exceptions, of rocks differing in character, cannot, even 
in that age, have been much more elevated than at the present 
day. But, it has been urged, the river, after depositing the 
Budleigh Salterton pebbles, made its way to the Midlands by 
some buried channel. The grave keeps its secrets, but, as 1 
have already said, the dominant quartzite pebbles at the former 
locality differ widely from those of the Midlands, and the idea 
that the latter have been sorted from the former, because their 
shape made them travel more easily, seems to me rather Uke 
expecting the riddlings of a peck to fill a bushel. In considering 
this question we must not forget, as some authorities appear 
to do, the great volume of material which must be broken up and 
transported to make not only the Bunter as a whole, but even its 
pebbles. The latter alone, as I pointed out in an address to this 
Section at Birmingham in 1886, is probably equivalent in bulk 
to a hill range twenty miles long, two miles wide and a thousand 
feet high. Neither Wales nor the Lake District could supply 
the right rocks, even if Dr. Marr would allow the latter to be 
visible at this epoch. In the north alone do we find almost 
all the rocks needful, and from this quarter volumes of material 
— sand and mud — as Professor Hull showed in two very sug- 
gestive papers more than 40 years ago,t must have travelled 
* See " Rounding of Alpine Pebbles," GeoL Mag., 1888, p. 54. 
t Quart. Jour. Geol. Soc, xvi. (1860), p. 63, and xviii. (18G2), p. 127. 
