It consists not only of chalk flints, but to a great extent of cherts and sandstones, such as are found at present in the forest-ridge of the Wealden and nowhere else.
Brownish cherts are found in the English Greensand; these often contain remains of sponges.
Some cherts contain tests of radiolaria, and correspond fairly closely to the siliceous radiolarian oozes which are gathering at the present day at the bottom of some of the deepest parts of the oceans.
In some of the folds of Arenig cherts diabase lavas appear, which occupy small lenticular areas.
The pebbles of the basal conglomerates are derived chiefly from the underlying platform of greywackes and shales and from the Radiolarian cherts and volcanic rocks in the tableland to the south.
The occurrence of marked earth-movements since Pliocene times is indicated by the nature of the deposits of Barbadoes, where radiolarian cherts have furnished two echinids which are described by Dr Gregory as deep-sea forms.
Footnote 88: The Radiolarian Cherts of the Lower Carboniferous rocks of Devon, and the associated sediments, together with the unconformity between these and the Upper Carboniferous beds are described by Messrs Hinde and Fox, Quart.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "cherts" in a variety of sentences. We hope that you will now be able to make sentences using this word.
