about twelve or fourteen yards: it forms a close measure, and I apprehend supports the water collected by the open strata which repose upon it, for water is always found either in the chalk or in the ferruginous sand immediately below it, the well sinkers never having occasion in this district to go deeper.
The next in order, No. 5 of the section, is a stratum of grains of quartz, which for the most part are conglomerated into sandstone of different shades of colour, from a dark brown to a light grey, while in some places loose sand predominates. Marine shells are found in this stone, each species appearing to be restricted to certain laminæ of the stratum: in the sandy portions I have never observed any organic remains. I consider this measure as considerably thicker than either of the two incumbent ones, Nos. 3 and 4.
I now come to the lowest visible stratum in our district, No. 6 of the section, which I term the shale stratum. It generally makes its appearance in valleys, and its thickness I cannot estimate, for I do not know where it exhibits any thing like a den undated termination. My brother (Mr. Thomas Bogg of Louth,) and myself have bored in this stratum to the depth of a hundred yards near the village of Donington, on the west side of the river Bain, and found it to consist of the following varieties.
