632 MINERALS OF THE BUNTER PEBBLE-BED. [Nov. 1902, 
cation of a method of research devised by Prof. Sollas. The mere 
thickness of beds was an imperfect indication of the source of the 
material. Thinning might take place either towards, or away 
from the source; and in many cases the thickness appeared to be a 
measure of the rate of depression, rather than an indication of 
proximity to the source of supply. From a consideration of the 
nature of the materials, the Author had made it probable that the 
main source of supply of the Lower Triassic beds of South-western 
England had been the southern part of the Armorican Range, now 
largely denuded away. He had also recognized the incoming of 
new materials immediately to the south of the old buried east-and- 
west ridge which divided the Triassic basin of the Midlands from 
that of the South-western area, and against which the members 
of the Trias overlapped on each side. This gentle ridge—a_ relic 
of the northern portion of the Armorican Range—although largely 
covered by Keuper Marls, appeared to have persisted in part to a 
later date, and it seemed possible that it might have furnished some 
of the materials of the Triassic deposits in the trough to the south. 
The PrestpEnt expressed his pleasure at finding that the study 
of the finer materials of the English pebble-beds had now begun 
in earnest, and that the Author had already reached results 
which were of such value and interest. Hitherto, Midland geolo- 
gists, who looked upon the Trias as their especial formation, 
had been content to draw their conclusions respecting the probable 
source or sources of the Triassic sediments from the study of the 
pebbles and the larger rock-fragments, and this paper marked 
a new epoch in this kind of geological research. It was grati- 
fying to note that the Author inferred, from his study of the 
microscopic materials, the same general direction of south-to-north 
travelas had long since been inferred for the Triassic pebbles of the 
South of England by J.W. Salter, Prof. Bonney, and others. Midland 
geologists, however, claimed that ridges existed in the Midlands in 
Triassic times, from which some of their local pebble-beds and sand- 
stones had been derived; and it was interesting to see, from the 
Author’s results, that the view of the derivation of all, or practically 
all, the materials from lost Armorican ridges below the English 
Channel or in Britanny ought not to be too closely pressed. 
Indeed, there was much to be said in favour of the view that some 
of the lost pre-Triassic Midland ridges were made up of rocks of 
Armorican type. 
The AutHor thanked the Fellows for their kindly reception of 
his paper, and referred to the great value of Prof. Sollas’s method 
of raineral separation, by means of which much of his work had 
been done. With reference to the red rocks of Anglesey mentioned 
by Mr. Greenly, the Author stated that he had not examined them, 
but that, as in the West of England, it was possible to draw a broad 
mineralogical distinction between the Permian, the Pebble-Bed, and 
the Red Rocks of higher horizons, this might also be possible in 
other areas. In reply to Prof. Groom, the Author said that he had 
been so far unable to prove that any characteristic mineral had 
been derived from the ancient ridge of land to the north. 
