Sept. 9, 1886 | 
considerable force on the eastern side of the Pennine Chain, 
have a great development in Lancashire and Cheshire, and thin 
away towards the south-east, almost disappearing in eastern 
Leicestershire and in Warwickshire. As the Trias is followed 
southwards, along the valley of the Severn, the Bunter in like 
way dies out, while the Keuper marls may be traced on into 
Somersetshire and Devon. In that region also there is a grand 
development of the lower and coarser members. As might be 
expected, there are considerable differences between the lower 
Triassic deposits of the northern and southern areas, so that it 
will be convenient to speak of them separately. The northern 
group, as is well known, is separable in the Midland and_north- 
western district into the Lower Bunter sandstone, the Pebble- 
beds, and the Upper Bunter sandstone, over which come, more 
or less unconformably, the Keuper sandstones. Pebbles are 
either absent from, or very rare in, every part of the Bunter 
except the pebble-bed, and are generally small and scarce in the 
Keuper sandstones, except inthe basement breccias. It will be 
convenient to make a few remarks on them before dealing with 
the associated sands and sandstones. The pebbles in the Bunter 
conglomerate are most abundant, and generally attain the largest 
size in the Midland district. Towards the north-west, though 
the conglomerate attains a thickness of more than 500 feet, 
pebbles are rarer and smaller, and this, I believe, is also the 
case in Yorkshire, though the thickness of the deposit is not so 
great. I can, however, answer for the occurrence of pebbles of 
fair size and in considerable abundance for some distance to the 
north of Retford. In the Midland district they are very fre- 
quently from about 2” to 4” in diameter, though smaller are inter- 
mingled and occasionally some of large size ; these attain in 
certain localities to a diameter of 6”, or even a little more. The 
majority, as far as I know, are well rounded. In this district 
many different kinds of rock are found in the conglomerate ; the 
most abundant are quartzose—vein-quartz, quartzites, and hard 
grits or sandstones. Besides these we find chert and limestone 
from the Carboniferous series, various fossiliferous rocks of 
Silurian, Ordovician, and possibly Cambrian age, with mud- 
stones and argillites, more or less flinty, of uncertain date. 
Feldstones, using the term in a wide sense, are not rare, and 
granites or granitoid rocks sometimes occur. These, however, 
together with the scarce fragments of gneiss and schist, are usu- 
ally very decomposed. A hard quartz-feldspar grit, sometimes 
very like a binary granite, may be found, and I have noticed 
a peculiar black quartzose rock of rather schistose structure. As 
the lithology of the Bunter conglomerate has already attracted 
the notice of more than one author, I shall restrict myself to a 
brief mention of its more salient features. The most abundant 
rock is a quartzite, frequently so compact as to give a rather 
lustrous sub-conchoidal fracture, in which the individual grains 
can be with difficulty distinguished. In colour it varies mostly 
from white to some tint of grey, but is occasionally “liver- 
coloured.” Rather obscurely marked annelid-tubes are the only 
organic indications which I have observed in these quartzites, 
and these are very rare. Under the microscope the rock con- 
sists chiefly of quartz fragments, of various forms in different 
specimens, with an occasional fragment of feldspar (sometimes, 
I think, silicified), a flake of white mica, a grain of tourmaline, 
and of an impure epidote (?). Asa rule it is easy to distinguish 
this quartzite from the other indurated arenaceous rocks which 
occur in the conglomerate, especially from those containing 
fossils. 
The above-described quartzites differ in appearance both 
macroscopically and microscopically from those of Hartshill, the 
Lickey, and the Wrekin district, but they closely resemble the 
most compact variety, which I have already described as occur- 
ring in boulders in coal. They have also an extraordinary like- 
ness to quartzite pebbles in Old Red Sandstone and Lower Car- 
boniferous conglomerates of Southern Scotland and to the 
quartzites of the Northern and Western Highlands, already 
described, a liver-coloured variety of which, as I have been in- 
formed, occurs in the island of Jura. These quartzite pebbles, 
to my knowledge, may be traced into Lancashire on the one 
side of the Pennine Chain and to beyond Retford on the other. 
The quartz-feldspar grit consists mainly of quartz and feldspar, 
obviously the debris of granitoid rock. I have found it at 
various localities on the northern margin of Cannock Chase, and 
_ have received specimens from the Bunter beds near the Lickey 
and near Nottingham. The rock, macroscopically and micro- 
scopically, presents an extraordinary resemblance to the 
Torridon sandstone of North-West Scotland, and differs from 
NATURE 
447 
every other rock which I have seen 27 sé in any other part of 
Britain. The nearest approach to it is the quartz-feldspar grit, 
already mentioned as having been struck in the Gayton boring, 
Northamptonshire, but this has a calcareous cement. The feld- 
stones vary from micro-crystalline to glassy rocks more or less 
devitrified, some being slightly scoriaccous. They may be 
classified lithologically as quartz-felsites, rhyolites (more or less 
devitrified), quartz-prophyrites, porphyrites, and old andesites. 
Some specimens contain a considerable amount of tourmaline, 
and I have seen this mineral in the vein-quartz pebbles. It also 
occurs rather abundantly in a very hard, black quartzose grit. 
I have received varieties of feldstone, which I have found on 
Cannock Chase, from the Bunter beds of the Lickey and from 
Nottingham. In Staffordshire pebbles of granitoid rock, gneiss, 
and schist are not only rare, but also generally too rotten to 
admit of examination; but I found a few months since, in the 
conglomerate at Style Cop, near Rugeley, two pebbles of a 
whitish gneiss, which appeared to me to indicate a secondary 
cleavage-foliation, such as may be observed in many parts of the 
Scotch highlands. The black quartz-schist already mentioned 
exhibits a peculiar ‘‘squeezed-out” structure, which ordinarily 
indicates that the rock has undergone great pressure. 
The sandy matrix and associated sandstones of the conglomerate 
beds, together with those of the Upper and Lower Bunter, and 
of the Lower Keuper, consist mainly of quartz grains, most of 
which appear to have been derived originally from granitoid 
rocks. They are often more or less angular, but at certain 
horizons, as described by Dr. Sorby, Mr. Phillips, Mr. G. H. 
Morton, and others, well-rounded grains are so abundant as to 
suggest an exposure to the action of the wind, They are often 
stained red with iron peroxide, and mixed with more or less 
earthy matter. In Cheshire and Lancashire recognisable grains 
of feldsrar have been noticed by Mr. Morton and others, and 
probably this mineral is, in most cases, the source of the 
argillaceous constituents which are often intermingled with the 
quartz grains. Flakes also of white mica are sometimes rather 
common. Sofar as I have been able to judge, distinct grains of 
rolled feldspar are commoner in the north-western district than 
in Staffordshire, where, however, mica-flakes are sometimes rather 
abundant. 
The Keuper sandstone seems to me to differ from the above 
only in the general absence of the red colour, and in‘a more even 
bedding, especially towards the upper part (the waterstones), 
where they are interbedded with the marls. The appearance of 
these last suggests that the currents were gradually losing strength, 
and only capable of transporting the finer feldspathic detritus with 
occasional tiny plates of mica. 
The lithology of the lower part of the Trias in the southern 
area is as yet imperfectly worked out, and a rich harvest awaits 
the student. My own knowledge of it is but superficial, so that 
I must pass it by with a brief notice. The great beds of breccia, 
so finely exposed on the South Devon coast, are crowded with 
fragments, sometimes of large size; these have clearly been 
derived from the older rocks which are still in part exposed to 
the west and south-west, and probably had once a much greater 
extension in the latter direction. Fragments of Devonian lime- 
stone, grits, and slate, together probably with other Paleeozoic 
rocks, earlier and later, are mingled with granites, resembling 
those of Cornwall and Devon, and many varieties of more com- 
pact igneous rock. The fossiliferous quartzite pebbles which 
occur mingled with others in the Trias at Budleigh Salterton, 
have been discussed by the late Dr. Davidson in an exhaustive 
memoir (‘British Fossil Brachiopoda,” Jem. Palaont. Soc. vol. 
iv. p. 317). _ He refers the majority of the fossils obtained from 
them to the Lower Devonian age, but a few are Caradoc, and 
four occur in France in beds which are either Llandeilo or per- 
haps a llttle older. As the first two formations are represented, 
lithologically and palaontologically, on the opposite side of the 
Channel in France, and the third is at presentgonly known to 
occur in the Gres Armoricain of that country, he thinks it 
probable that these pebbles have been derived from rocks which 
are now concealed beneath the waters of the Channel. It may 
then, I think, be taken for granted that land to the west and 
south-west has supplied the materials of the Lower Trias of the 
southern district of England, and I may add that there is every 
reason to believe that outliers of the formation itself still exist 
beneath the sea. 
The so-called dolomitic conglomerates, which occur chiefly in 
2 In an excellent paper published in the Proceedings of the Liverpool 
Geological Society, vol. v. p. 52+ 
