On the Matrix of the Suffolk Chalky Boulder-Clay

Abstract

Much study has been bestowed, upon the boulders included in the Glacial Clays, their nature, origin, and distribution. The matrix in which they lie has received comparatively little attention. Yet the matrix, in many or most, forms by far the largest part. I have been endeavouring to study this matrix under the microscope, by washing it, shaking it up with water, and so separating the material which will settle quickly to the bottom from that which remains longer in suspension. The process has to be repeated until the water remains clear, else dust still suspended dries on the surfaces of the grains which had settled and masks them from examination. I have collected and dried this finer dust, but it cakes together: I have not obtained from it much information. The coarser material, that which subsides first, forming from 40 to 75 per cent. of the whole, dries to a sand or powder and lends itself readily to examination with the microscope. I have tried several methods, and have succeeded best by inspection under direct daylight of the powder strewn on a slide. Inspected in this manner, Glacial Clays from localities in East Anglia tell something of their sources. I have examined specimens from places along a belt of country in Suffolk extending from Lowestoft to Bury St. Edmunds, a distance of more than 50 miles; Lincolnshire material dredged up in deepening the ship-channel to Boston (kindly sent by Mr. W. H. Wheeler, C.E.); Cambridgeshire specimens from Ely Cemetery and

The distribution, variation and origins of pre-Devensian tills in eastern England

“…Although nearly one hundred years have passed since Wood (1880) established the distribution of the Chalky Clay (or Chalky Boulder Clay) and since much of the complex succession of the Cromer Tills and associated beds in the Norfolk cliffs was clarified by Reid (1882), there is still considerable uncertainty about the relation and origins of the pre-Devensian tills of eastern England. Particular confusion prevails on the stratigraphy of the Chalky Boulder Clay itself and PRE-DEVENSIAN TILLS IN EASTERN ENGLAND 537 its correlations in East Anglia and the east Midlands (West 1973;Phillips 1976;Shotton et al 7 7 ) • Some factors that have delayed agreement, and that the present study seeks to avoid, include a general neglect of the lithology of the till matrix in favour of the more easily recognizable but volumetrically far less im portant erratic stones (although Hill (1902), Boswell (1916) and Solomon (1932 a, b)have shown the potential value of mechanical and mineralogical analyses); a conspicuous lack of quantitative data; a tendency for far-ranging conclusions to be based on very few sites; the correlation of widely separated deposits by means of a single and unquantified character, such as chalkiness, without any other lithological or age control (Cox & Nickless 1972, p. 81); and sometimes inadequate definitions of the till units being studied.…”