Science · 6 pages · 12 min
Why erratics sit far from their bedrock
Ice carried the foreign boulder, then melted and set it down.
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From the opening
An erratic is a boulder whose rock type does not match the bedrock beneath it, because glacier ice carried it in and set it down. It can sit far from its source because ice moves a block intact, without the long abrasion a river would use to destroy it. The opening covers a rock type that does not match, plucking, carrying, and melting out, and tracing the block to its source.
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Inside
- A rock type that does not match
- Plucking, carrying, and melting out
- Tracing the block to its source
- Why a cliff rockfall is different
- Where the idea stops applying
- A distinction worth keeping
Sources
- Glacial transport of mismatched bedrock blocks
- Indicator erratics used to reconstruct ice-flow paths