Culm Measures
From Wikipedia, the free encyclopedia
The Culm Measures are a geological formation of the Carboniferous period that occur in south-west England, principally in Devon and Cornwall. They are so called because of the occasional presence of a soft, sooty coal, which is known in Devon as culm.
The majority of the formation consists of shales and thin sandstones, but there are also occurrences of slate, limestone and chert.

