the bedrock
conglomerate
rounded pebbles · a river laid them down
The tell
Rounded pebbles of every kind, cemented into one stone. A river tumbled the corners off long before the stone healed itself together, and those worn-round pebbles are the whole test. Sharp, angular chips instead of pebbles means breccia.
The family sorts out fast. Jasper-red pebbles locked in white quartzite is puddingstone, the rare one. Suspiciously even pebbles in one flat gray cement is concrete off a pier. Everything else is honest conglomerate.
What it gets mistaken for
- puddingstone
- breccia
- concrete
- gravel bar, frozen
The facts
- also calledround pebbles mean a river · not puddingstone
- ageage varies
- classsedimentary
- where it turns upstatewide glacial float
- the field markpebbles are rounded · breccia's chips are angular
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