The Devensian Stage

© Craven & Pendle Geological Society

Antarctic Survey Team

© Jane Francis Ph.D. Leeds University

The Glacial Record

The Devensian cold stage and Holocene temperate stage did much to shape the landscape of northern England. The highlands of Scotland at this time was dominated by ice sheets while further south, independent ice caps were present over the Lake District, the Cheviot Hills and parts of the Pennines. At its maximum extent the ice covered the most of northern England. Typically, on retreat, periglacial processes modified much of the glacial landscape. The end of the Devensian glaciation is characterised by climatic fluctuation and a great deal of sediment accumulation. As we then enter the Holocene temperate stage, sea level is seen to rise, there was a reactivation of river systems, major changes in vegetation and of course human modification of the landscape.

There are many aspects of the Devensian glacial record that ought to be considered if you wish to fully understand the nature of ice ages. Suffice to say that the Devensian can be conveniently divided into an Early Devensian (115 - 50 ka), Middle Devensian (50 - 25 ka) and Late Devensian (25 - 10 ka). The Late Devensian is the part that played the pivotal role in moulding the landscape we see today. In order to understand the Ice Age, consider the following:

Timing and extent of the ice sheet

The ice thickness

Flow patterns and scale of the Ice sheet

Iceberg production / surge behaviour

Basal thermal regime

Erosion and deposition patterns

Erratics

Glacial erosion in uplands

Glaciokarst

Glacial meltwater erosion

Glaciofluvial sediments and landforms

Extent and thickness of till cover

Glacial moraines

Glaciolacustrine deposits

Drumlin formation

Summary

The numerous glacial events affecting northern England have left a significant impression on the landscape. A full repertoire of events from full ice sheet (glacial) to restricted ice cap / corrie-glacier (stadial) are well illustrated in the landforms and the sedimentary record. No doubt the ice from events prior to the Devensian occurred but palaeoglaciological reconstructions are still poorly constrained.