On the Occurrence of Thanet Beds and of Crag at Sudbury, Suffolk

Abstract

I. Thanet Beds. The newer Tertiary deposits of the Eastern Counties have had such a power of fascination over geologists that the older beds have been left almost unnoticed: indeed since the description of a few sections in Mr. Prestwich's essays on the Lower London Tertiaries, which have now been published 20 years and more, I know of but one paper (and this probably known to very few geologists)* that gives us any information about that series in the district in question, whereas the number of papers that treat of Crag and Drift is legion. It has therefore been an agreeable surprise to me to find, in the course of my Geological Survey work, that there are fine sections of the older Tertiary beds in Suffolk and the neighbouring part of Essex; and it was with some astonishment that I saw one of the finest sets of sections in the London Basin round the town of Sudbury, on the border of those two counties. These sections convinced me that the lowest member of the Lower London Tertiaries, the Thanet Beds, crops out along part of the northern edge of the Tertiary district, an occurrence of which I had a very slight suspicion from other sections near Ipswich. Mr. Prestwich has, indeed, doubtfully referred some of the sands of the northern outcrop to this division, though without describing any section; but he does not notice the particular part where it is now to be seen in many large and clear pits,