Nodular synonyms

A series of black shales with nodular limestones, the Pendleside series, rests upon the Mountain Limestone on the east, south and north-west; much of the upper course of the Derwent has been cut through these soft beds.

The Coal Measures, forming the third great member of the Carboniferous series, consist of alternations of shales and sandstones, with beds of coal and nodular ironstones, which together make up a thickness of many thousands of feet - from 12,000 to 14,000 ft.

The commonest state of aggregation is that of radially arranged fibres, the external surface of the mass being globular, nodular or stalactitic in form.

Many of the impure substances thus utilized are not strictly phosphorite, but pass under such names as " rock-phosphate," or, when nodular, as " coprolite " (q.v.), even if not of true coprolitic origin.

They consist of fine clays with nodular calcareous concretions rich in fossils.