THE TERTIARY HISTORY OF EAST YORKSHIRE

Abstract

Since the discovery of the so-called Bridlington Crag in 1835 (2) the possible existence of Tertiary rocks in Yorkshire has been a matter of speculation but Phillips’ conclusion that Tertiary strata did not occur in Yorkshire has been accepted by most Yorkshire geologists. In 1904, Stather (13) reported the presence of scattered pebbles of quartzite over the Wolds even above the drift limit and concluded that they represented either the relics of an early glaciation or even of a Tertiary stratum. There exists in the Hull Museum a map produced by R. Mortimer, never officially published, showing a distribution of masses of sand and gravel covering the Chalk of the Wolds and allocated by him to the Eocene, Miocene and Pliocene periods. There is now no indication of such sand being exposed so far as the writer has been able to discover but the late Mr. Stather gave the author a sample of sand collected some thirty or forty years ago from Thixendale, one of the localities marked by Mortimer. The analysis of this sand is given later in this paper. Others of Mortimer’s areas seem to be simply the ordinary chalk gravel of glacial date. Among the many tumuli which are scattered on the Yorkshire Wolds and were excavated by J. R. Mortimer (10) there are some, 12 in all, which are described as having been dug, not in Chalk, but in sand which existed as a pipe in the Chalk. All these tumuli are found above the drift ...