Some of the members of this formation agree with those of the Coal-field, viz. coal, shale and sandstone; but other rocky masses also attend the lead mine measures and serve to distinguish them. These are the coarse grained sandstone called the millstone grit, sandstone with impressions of marine shells, shale with the encrinal fossil, the encrinal limestone, siliceous hornstone or chert, and basalt in beds or in overlying positions.
The four first of the following sections are those which I have already referred to as representing not inaccurately the series of beds in the mining field. The additional sections from Blanchland resemble the upper part of the Aldstone moor section, and that from Weardale the lower. I have added the section from Arkendale in Yorkshire for the sake of comparison.
Section of the Lead-mine Strata at Hely Field on the river Derwent.
| Fs. | Y. | Ft. | In. | Fs. | Y. | Ft. | In. | ||
| Slate still | 2 | 1 | ─ | ─ | Brought up | 35 | ─ | ─ | ─ |
| Plate | 3 | 1 | ─ | ─ | Hard hazle | 2 | 1 | ─ | ─ |
| Different girdles beds | 2 | ─ | ─ | ─ | Grey beds (Thislayers of slate clay and sandstone alternating) | 1 | ─ | ─ | ─ |
| Plate | 2 | 1 | ─ | ─ | Freestone | 7 | ─ | ─ | ─ |
| Freestone (fine grained sandstone) | 7 | ─ | ─ | ─ | Plate | 1 | ─ | ─ | ─ |
| Coarse hazle | 1 | 1 | ─ | ─ | Hazle or Slate | 2 | 1 | ─ | ─ |
| Plate and Blue whin | 1 | ─ | ─ | ─ | Plate of Famp | 2 | ─ | ─ | ─ |
| Plate and grey beds | ─ | ─ | 2 | ─ | Hazle and Plate | 2 | 1 | ─ | ─ |
| Hard stone and whin | 1 | ─ | 2 | ─ | Plate | 2 | ─ | ─ | ─ |
| Plate and Whin | 1 | 1 | 2 | ─ | Hazle or Slate | 1 | 1 | ─ | ─ |
| Plate | 2 | 1 | ─ | ─ | Plate and Grey beds | 1 | 1 | ─ | ─ |
| Millstone grit | 5 | ─ | ─ | ─ | Thin stratum of Grey beds | 15 | ─ | ─ | ─ |
| Plate | 4 | 1 | ─ | ─ | |||||
| ──────── | ──────── | ||||||||
| Carried up | 35 | ─ | ─ | ─ | Fathoms | 75 | ─ | ─ | ─ |
