Tropical limestones: Bee Low
The White Peak of Derbyshire is composed mostly of several types of limestone, deposited in marine conditions in the early Carboniferous period, some 330 million years ago. At this time, Britain's climate was distinctly tropical and the limestones accumulated beneath a clear, shallow, warm sea fringed with reefs. The limestones are composed of the shells of organisms that lived in these tropical seas. These shells are predominantly made up of the mineral calcite (calcium carbonate). Examination of most limestone outcrops will show beds containing brachiopods, crinoids, corals and other fossil fragments. The shell debris would have been slow to accumulate and the many hundreds of metres of limestone we see today probably took about 40 million years to form.
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Most limestones in Derbyshire are pale coloured, flat-lying and remain uniform over wide areas. The limestones have been divided by geologists into a number of named rock units, or formations. The Bee Low Limestones have a large outcrop area and are typically thick-bedded, pale grey limestones composed of broken shell debris. They are of high chemical purity and are of considerable economic importance as they are the source of most of the limestone quarried in Derbyshire. |
