City Research Online

Abstract

150m O.D. between Watford and Ware, a total distance of approximately 30km.

The considerable thicknesses of Anglian sediments found here, and which have hitherto been largely neglected by the engineering fraternity, have been the focus of attention by those whose particular interests lie in the reconstruction of the Pleistocene environments in this area.

Detailed lithostratigraphic sequences of the tills and associated proglacial sediments have been established at five quarry sites selected for study in the Vale. At least two, possibly three, different tills are recognised and described which satisfy the various criteria for a lodgement method of emplacement within the basal traction zone of separate ice sheets.

A programme of fieldwork is described involving in situ testing and sampling of these tills. Clast fabric vectors have been established for these sediments, thus providing a framework within which undisturbed sampling of fabric oriented soils could take place. A new till fabric instrument has been developed for this purpose.

The considerable quantities of colloidally inactive chalk present in the tills is a particularly distinguishing characteristic and, despite their classification as matrix dominant tills, is shown to account for their relatively low activity.

The presence of disseminated carbonate in these soils is also shown to have an effect on other measured engineering properties. The results of tests carried out on samples of both undisturbed and reconstituted till clearly indicate the presence and effect of a cement, possibly calcite, in the matrix.

Based on the combined criteria of microfauna and measured fabric vectors, the probable geographical and geological provenance of the source material for these tills is speculated.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Departments:	Doctoral Theses School of Science & Technology > School of Science & Technology Doctoral Theses School of Science & Technology School of Science & Technology > Engineering

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