Glacial geomorphology of Glasgow with particular reference to the Drumlins

Abstract

The events of the last glaciation and deglaciation in Glasgow were studied and the stratigraphic sequence of drift deposits re-examined using borelog records and field mapping. Drumlins and their internal material were studied in order to examine theories of drumlin origin and to develop a broader theory of their formation.

Over 8000 borelogs were collected and analysed in order to study drift stratigraphy, drift thickness and rockhead topography. Cross-sections were drawn to clarify the drift sequence. The Clyde buried channel and its infilling deposits were mapped from borelog records, and both appear to be subglacial in origin.

The characteristics of red and grey till were studied using till fabrics, fissure fabrics, palaeomagnetic and pebble lithology investigations. Till samples were geotechnically analysed, measurements of moisture content, consolidation, shear strength, and particle size distribution being made. Although great variability was found in the tills, they appear to have been deposited contemporaneously.

No relationships could be detected between drumlins and terrain characteristics. Fissure studies suggest drumlin growth by accretion. Till layers and palaeomagnetic work suggested till depositional rates were high. These high depositional rates were possibly due to changes in the subglacial environment resulting from removal of water. Every drumlin does not appear to require a solid core, only a minimum size to withstand ice forces.

Field mapping, fabrics and drumlin orientation indicate ice flow eastwards across the area. The mode of deglaciation appears to have been unusual since ice apparently remained in Glasgow while adjacent areas, including the Firth of Clyde, became ice free.