Echinoid preservation in the Upper Estuarine Limestone of Blisworth, Northamptonshire

Abstract

SUMMARYThe study of echinoids and their associated limestones in the Upper Estuarine Series of Blisworth has shown that the echinoid tests have been preserved in two ways. (1) Without spines, jaw apparatus or apical disc. When whole, such tests are usually full of sediment. Echinoids of this type are usually associated with clean well-sorted fragmental limestones. (2) Bearing spines and with apical disc and jaw apparatus in place. When whole, the tests are usually full of clear crystalline calcite. Echinoids of this type are usually associated with poorly sorted, complex, muddy limestones with a high proportion of terrigenous material. The sedimentary environment and the relative rate at which the echinoid material passed through the depositional interface appears to have controlled both the limestone lithology and the condition of the echinoid material.