forming in fact a hard compact magnesian limestone. This variety will give 36 or 38 per cent. of carbonate of magnesia. All the varieties are of a yellow colour, and like the magnesian limestone of the north, it often exhibits black spots throughout its substance, and it frequently contains impressions of shells.
The analysis of the compact variety, conducted in the usual way, gave me of
| Carbonate of lime | 53 | .5 |
| Carbonate of magnesia | 37 | .5 |
| Oxyd of iron | .8 | |
| Insoluble matter | 7 | . |
| Loss | 1 | .2 |
| ────── | ||
| 100 | .0 | |
| ────── | ||
Now with regard to its geological relations, it in no respect differs from the limestone conglomerate which I have mentioned as the lowest bed of the red ground formation. I have traced it in a continued line by the sea side from Portishead to Clevedon, and it every where contains the same fragments and every where lies horizontally and unconformable upon the inclined strata (which are there the old red sandstone,) in the same way that the usual red grained conglomerate does. It is therefore plainly to be considered as the lowest stratum of the red ground formation, and consequently succeeds immediately to the coal deposit.
It seems to me that the magnesian limestone of the north of England may be referred to the same formation. In Thomson's Annals there is lately a short notice, of a paper read before the Geological Society by Mr. Winch, upon the magnesian limestone in the north of England, in which it is stated that the Tees
