But all underclaysagree in two points: they are all unstratified.
Sometimes, however, it is a soft clay, at others it is mixed with sand, but whatever the composition of the underclays may be, they always agree in being unstratified.
The underclays are found beneath every bed of coal.
On botanical grounds, Brongniart and Lyell conjectured that they formed the roots of other trees, and this became the more apparent as it came to be acknowledged that the underclays were really ancient soils.
The mode of formation of the underclays is not certainly known.
Both these clays may be equally refractory, but the underclays are those to which the term fireclay is usually applied.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "underclays" in a variety of sentences. We hope that you will now be able to make sentences using this word.
