Squaring The Circle, A Randall Carlson Podcast #80 Speak To The Earth and It Shall Teach Thee: Younger Dryas Series S1E4
Feb 18, 2026
A deep dive into Younger Dryas landforms, from kettle lakes and drumlins to eskers and outwash plains. Clear definitions of glacial deposits, moraines, and subglacial meltwater channels. A walkthrough of stratigraphy and climate signals like gyttja that mark cold-warm-cold oscillations. Discussion of timing from Older Dryas to Holocene and why this interval matters for human prehistory.
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Quaternary Defined As Pleistocene Plus Holocene
- The Quaternary combines the Pleistocene and Holocene epochs and spans about 2.5 million years.
- Randall explains the term origins: originally 'Quaternary' meant four divisions, now represented by these two epochs.
How Kettle Lakes Form From Buried Ice Blocks
- Kettle lakes form when large blocks of glacial 'dead ice' become buried by sediment and later melt, leaving depressions.
- Randall uses till and melt-deposited clay to show how embedded ice blocks produce kettle topography and lakes.
Drumlins Record Subglacial Flow Direction
- Drumlins are elongated, blunt-ended hills formed beneath glaciers and indicate subglacial processes rather than surface deposits.
- Randall highlights that drumlins always occur under ice and that their orientation (blunt upstream, tapered downstream) records flow direction.