of its direction a vein is found traversing Walker colliery, and crossing the Tyne at Walker near Mr. Reay's house. In the latter colliery it has been observed and described by Mr. George Hill, to whose accuracy I owe the plan given in Plate 3, and the following particulars.
The dyke is well defined, and the Plate represents its horizontal section taken at the level of the high main coal 100 fathoms from the surface. It occasions no alteration in the level of the coal measures, and the depth to which it intersects them is unknown. The dyke has been cut through by horizontal drifts in four places, from which the following sections have been taken.
| Sections at A. A. the two western drifts. | ||||
| I. | Coak | 6 | ─ | ─ |
| 2. | Hard greenish whinstone, firm and unbroken | 3 | ─ | ─ |
| 3. | A fissure filled with nodules of whinstone and post imbedded in a cement of blue slate |
─ | ─ | 9 |
| 4. | Loose fragments of whinstone and post imbedded in blue slate but commonly less deranged |
3 | 2 | 3 |
| 5. | Hard greenish whinstone similar to No. 2. | 6 | ─ | ─ |
| 6. | Coak | 3 | 1 | 6 |
| ─────── | ||||
| Yards | 22 | 1 | 6 | |
| ─────── | ||||
| Sections at B. B. the two eastern drifts. | ||||
| 1. | Coak very hard | 1 | ─ | ─ |
| 2 | A confused mixture of nodules of sandstone, whinstone, pyrites and calcareous spar (the sandstone predominating) cemented together by pieces of blue and black slate. Water was found, and there was a plentiful discharge of inflammable gas, while the drift was being made |
6 | ─ | ─ |
| 3. | Compact post, with pieces of black argillaceous slate occurring at intervals |
3 | 1 | 6 |
| 4. | Hard greenish whinstone | 8 | 1 | 6 |
| 5. | Coak like that of No.1 | 1 | ─ | ─ |
| ─────── | ||||
| Yards | 20 | ─ | ─ | |
| ─────── | ||||
