Humberside Geologist no 4

REPORT OF EXCURSION TO KELSEY HILL.

June 16th. 1888.

[Note by Mike Horne - This visit to Kelsey Hill, about half-way between Burstwick and Keyingham, (NGR 238267) was the first Field Meeting of the Hull Geological Society. The original manuscript of this report is in the Society's archives and has been reproduced here in the form written by Dr. F. F. Walton, though the manuscript has been altered in pencil by another hand. The Memoir referred to is Clement Reid's "The Geology of Holderness and the adjoining parts of Yorkshire and Lincolnshire" published in 1885.]

Kelsey Hill forms one of that long line of sand and gravel hills which extends along the whole length of Holderness from Kilham on the Wolds to the Humber at Paull. Those gravel hills represent a period in the History (Geological) of Holderness when from some cause or other the intense cold, which previously existed, - became ameliorated - as a somewhat warmer climate took its place, - permitting the existence of animal life in the locality which the subsequent increase of the cold afterwards drove out again. During this period the gravels known as the Interglacial series were deposited. It is thought that several of these Interglacial intervals have occurred during the whole of the Glacial Period.

The gravel at Kelsey Hill is shingly and false-bedded, with beds of sand. Small blocks of scattered limestone have been found in it; proving that it has been partly derived from an older boulder clay. Near Kelsey House the gravel is covered (as is stated in the Memoirs of the Geological Survey) by a purple chalky boulder clay. This boulder clay is very much weathered, though nearly 13 feet in thickness, the common occurrence of flints in it seems to show originally it was chalky - but most of the calcareous matter has been dissolved out. All the pits at Kelsey Hill present he same character of shingly current-bedded gravel and sand attaining a thickness of over 40 feet. The stones are principally flint and chalk with many foreign rocks derived from the boulder clays, but no large boulders; only one of any considerable size being see during the afternoon. Fossils from the Jurassic rocks, - as - ammonites, & Gryphaea incurva also occur. Among the stones are many blocks bored by Pholas, showing that in places the sea must have cut into base chalk, & not boulder clay. During the earlier part of this inter-glacial period the land was apparently bounded by the now hidden chalk cliff; though that feature is probably of older date; and the submergence was only to the present extent. Subsequently the land sank so that the present 100 foot contour line became approximately the shoreline. It is probable that this submergence was only gradual; & that is most likely that the sections at the foot of the Bridlington chalk cliff, & Kilham & Kirmington mark successive stages of the one period. (Note. - I think that this statement with regard to the Bridlington chalk cliff - requires more proof before finally accepting. F.F.W.) Of the beginning and end of this Interglacial Period nothing is known; but it is scarcely probable that the conditions could have changed suddenly from glaciation to a temperate climate & back again; but there must have been intervening stages. The one part of this period of which anything is known is represented by the beds formed when the submergence was about 100 feet. From mapping the deposits of this period the Geological Survey drew their map of Interglacial Holderness -; & this map shows how the sea must run up most of the valleys on the east side (at least) of the Wolds.

The marine gravels of the Interglacial Period dip towards the east - & disappear beneath the boulder clay. From borings which have been made in different places it is proved that they extend further to the east beneath the boulder clay though it is impossible to correlate them with any of the beds on the coast - which occur beneath different boulder clays & it is probable that they do not represent any of these coast sections at all; but rather that they lie below the cliff sections altogether.

Fossils. - The fossils of these marine gravels taken together may be described as slightly northern but not arctic, l0 or 12 of the species do not now range so far south as the southern half of the North Sea. The rest, with two exceptions, are living British forms, of these two exceptions - one - Tellina obliqua, - is an extinct Crag shell - a single valve of it was found at Laceby in Lincolnshire - and it is the only extinct mollusc yet known from these beds. This is not found at Kelsey Hill.

The other exception is a fresh water bivalve,- Corbicula (Cyrene) flumlnalis ;- it occurs at Kelsey Hill in great abundance and has also been found at Croxton, Co. Lincoln. These two localities are the only two where it has been found in the old Holderness Bay area. This mollusc is now extinct in Europe; and the nearest point to Kelsey Hill where it may be found living at the present day is in the river Nile.

Among the fossils found on the excursion may be mentioned, -

Buccinum undatum, Corbicula fluminalis,

Nassa reticulata, Tellina balthica,

Littorina (sqalida ?), Ostraea edule,

Dentalium entalis, Cardium edule.

on a previous excursion a portion of a rib apparently of some small mammal was found by the President.

Some black carbonaceous looking bands were noticed between the strata of the sand - these being noticed in the part of the pit furthest away from the railway.

The members attended in good number and a most enjoyable afternoon was spent.

In writing the above notes I have freely used the material contained in the memoir of the Geological Survey of Holderness and for further information would refer anyone to that book - which also contains a complete table of the fossils found in the Interglacial Series.

F.F. Walton.F.G.S.

[F. Fielder Walton (1860-1925) was the Society's President from its foundation in 1888 until 1898.]