QUARTZITE PEBBLES ON THE
J. W. STATHER, F.G.S.
(Read March 19th, 1903).
As is well known, the Yorkshire Wolds, composed in
part of flinty and of flintless chalk, extend in the form of a rough
crescent from Flambrough [sic]
Head to the Humber. The general dip of the Chalk is to the south-east,
swinging more to the east before it reaches the coast, and the general slope
of the upland is in the same direction, so that the higher parts of the
Chalk country are along the escarpments which overlook the Vale of York to
the west, and the Vale of Picketing to the north. To the south-east the
Wolds sink gradually beneath the Glacial Drift which covers Holderness, and
the surface of the Chalk in this quarter is considerably below sea-level.
It must be noted, however, that the
glacial deposits so abundant in Holderness and the east coast generally, do
not extend to the higher parts of the Chalk wolds, and that though the drift
which covers their south-eastern flanks rises in some places to a
considerable height, there is a large area of high land to the north and
xvest entirely free from recognisable glacial deposits, and this area has
been mapped as driftless by the officers of the Geological Survey. But on
these high level areas, in spite of the absence of glacial drift, it has
been found that quartzite pebbles occur in large numbers. The pebbles vary
greatly in size, but probably their average diameter is from two to three
inches. In colour they vary from a dull yellow to a yellowish red. They are
well rounded, and in this respect resemble the Bunter pebbles so abundant in
the Midland counties. These pebbles are
also generally accompanied by pebbles of a hard reddish sandstone, somewhat
larger than the quartzites, but fewer in number and apparently not so
waterworn. The scanty soil of the Wolds is
of course highly charged with fragments of chalk and flint, but the pebbles
in question can be distinguished from this local material at a glance.
It has not yet been ascertained whether
the pebbles occur over the whole of the western parts of the Wolds, but
judging from the areas in the neighbourhood of Riplingham, Bush Hill, High
Hunsley, Hessleskew, Millington, East Luton, and other localities which have
already been under observation, the general conditions of their occurrence
seems to be as follows:--
(1) The pebbles occur at high
levels, generally from 400 feet to 500 feet above sea level, near the
western escarpment of the Wolds.
(2) They are scattered unevenly over the
fields, sometimes few and far between, at other times averaging as many as
six pebbles to the square foot.
(3) The pebbles are rare on the sides of
the dales, but are the most plentiful on the high level (flat) lands which
.intervene between the dales; the rule being the flatter the land the more
numerous the pebbles.
(4) They also occur, as the only foreign
pebbles, in the chalk gravels which underlie the boulder clay at Hessle, and
they are also recorded from the old chalk breccias, Fairy Stones, &c., of
the higher Wolds.
In seeking for an explanation of the
presence of these scattered pebbles on the high Chalk wood it may be pointed
out that (1) no local rocks occur in situ from which the pebbles can have
been derived; that (2) the pebbles being limited to quartzites and
sandstones, cannot have come from the Glacial Drift to the east of the
Wolds, because these drifts are famous for the immense variety of rocks
represented amongst their boulders and pebbles ; that (3) for similar
reasons, neither can the pebbles be correlated with the gravels of the Vale
In writing to ask the opinion of my
friend Mr. G. W. Lamplugh some time ago with regard to these interesting
strangers, I received in reply a letter from which the following sentences
are, with his permission, reproduced :--
"I cannot even offer an opinion as to
what your quartzite drift on the top of the Wolds
may be. It may be well, however, to remind you of the 'Lenham Beds' of
Pliocene age that occur in scraps on the north Downs. Relics of this kind
might persist on the surface of the Wolds
where protected from glaciation even though a considerable thickness of the
underlying chalk had disappeared in solution. As the result of work in other
places since leaving York-
shire, I do not feel so confident that the Wolds
remained ice-free throughout the Glacial period. It is clear that they were
not overswept by the ice at the time that the Speeton moraine was formed,
nor at any later stage. But if evidence be found to indicate that they were
covered at an earlier period, I should take it very carefully into
consideration. Still, your materials scarcely suggest an ice-covering,
either from the west or east. You are working on interesting lines, and I
advise you to continue."
It would indeed be interesting if these
quartz pebbles should be the only surviving relics of some Pliocene or at
any rate Pre-glacial deposits hitherto unrecognised in
Yorkshire. But at present the evidence is too slight to bear the
weight of such a conclusion.
It may be remarked that in some high
level gravels of uncertain age in the south of England, beyond the limits of
the Great Glaciation, quartzite pebbles also occur, and have given rise to
In conclusion, the writer of these notes would like
to acknowledge the invaluable help he has received from Mr. G. W. B.
Macturk, both in the field and many other ways.
[Note -This article has been scanned in from original printed format
and then put through an OCR program by Mike Horne. The process may have introduced some new
spelling errors to the texts. Some original misspellings have been corrected.]
Copyright Hull Geological