Between 15,000 and 20,000 years ago, the Retford area was plunged into a deep freeze. Recent research has interpreted unusual cropmarks in the region as remnants of a fossil pingo.
Pingos are dome-shaped hills found in tundra regions where groundwater remains permanently frozen. In some places, ice lenses grow in the subsoil, pushing up these distinctive mounds. Such features form in regions where average temperatures reach -10°C, summers no warmer than 10°C, and winters perhaps as cold as -30°C.
In 1980, Derrick Riley mapped Romano-British fields and farmsteads around Retford using aerial photography, identifying a puzzling cropmark near Botany Bay Farm. In 2002, Daryl Garton and Jenny Brown studied this feature more closely, concluding that it was likely the scar of a former pingo.
Subsequent analysis of 2015 Google Earth satellite imagery largely confirmed their interpretation, as seen in the preserved circular impressions of ditches and ridges. These impressions include a layer of polygonal patterned ground sandwiched between two scars, indicating extreme thermal contraction during a period of continuous permafrost. Ground ice has since vanished from the Idle Valley, leaving only these traces of its existence.
Similar remnants of permafrost, such as patterned ground and pingo scars, can be observed throughout the East Midlands. They are visible via Google Earth Pro at www.tinyurl.com/groundpatterning or through www.IceAgeInsights.org. At Botany Bay Farm, these features serve as a reminder of the dramatic environmental conditions of the time.
Between two significant cold episodes – one around 15,000 years ago and another at 12,000 years ago – Late Upper Palaeolithic nomads took advantage of a warmer interval. Evidence of their hunting activities can be found at Creswell Crags, located just south-west of Worksop (www.creswell-crags.org.uk).
While January 2025 may feel cold, it pales in comparison to these ancient freezing conditions. Our hunter-gatherer ancestors displayed remarkable resilience and adaptability, retreating south across Doggerland (now submerged beneath the North Sea) as temperatures plummeted.
If only we could migrate to the south of France so easily!
Colin Baker contributed this piece after publishing a paper on the periglacial record in the Idle Valley, centred on Botany Bay Farm Babworth.