Quarterly Journal of the Geological Society of London/9/179
2. On the Occurrence of Caradoc Sandstone at Great Barr, South Staffordshire.By J. Beete Jukes, Esq., M.A., F.R.S., F.G.S.
Shortly after the publication of my memoir on the Geology of the South Staffordshire coal-field in the 'Records of the School of Mines' (vol. i, part 2), I received a note from Mr. Daniel Sharpe calling my attention to the occurrence of Caradoc sandstone at a spot on the eastern border of the Walsall Silurian district. Being in the district for a short time in March last. I visited the spot indicated by Mr. Sharpe, and found to my surprise a quarry I had previously overlooked. It is a very old quarry, much overgrown by bushes and brambles, and in a field which was, I believe, covered by standing corn when I surveyed the district in 1849. From these circumstances, although I had passed within a few yards of it, it escaped my notice.
On visiting it this year, I was accompanied by Mr. George Eglinton, the occupier of the ground, who was aware of the peculiar character of the sandstone, and who also guided me to another very remarkable little section, near Hay Head, which had escaped my previous observation from the same circumstance of being overgrown by bushes, which in the summer would render it invisible. The first-named locality is a little south of the sixth milestone on the Birmingham and Walsall road, in the fourth field S.S.E. of Shustoke Lodge. The old quarry is just below the summit of a small rising ground, which forms a distinct little ridge about 80 yards across and 200 or 300 long, sloping down gently on every side. The rock is a pale yellow or brown sandstone, in some places nearly white and purely quartzose, in others very ferruginous, marked by concentric rings of a dark brown colour, and containing little ochrey nodules. It had also small bands of highly calcareous grit, and some of the blocks had a central nucleus of white arenaceous limestone. It was traversed by joints in all directions, splitting it into very sharply angular fragments; and I was not able to detect the bedding with sufficient accuracy to state its dip, owing to the smallness of the portion we were able to expose. Some parts of it were crowded with fossils, which Mr. Salter has kindly determined for me.
|Phacops— truncato-caudatus ?||1|
|Clionetes lata (probably)||1|
|Rhynchonella—two plaited species||8|
|Rhynchonella—small smooth species||50|
|Fenestella (with close meshes)||1|
[J. W. S.]
Fragments of the sandstone were strewed over the upper part of the field near the quarry, but over the lower portion, as well as in the ditches on the other sides of the ridge, were found many fragments of limestone slabs with the ordinary Wenlock fossils in great abundance. I believe, therefore, that the Hay Head or Barr limestone (which is probably the same as the Woolhope) will be found to wrap round the foot of the ridge. The Permian boundary here makes a slight bend round the eastern side of the sandstone ridge.
The second locality is a little gully, just east of the house called Daffodilly, at Hay Head. The bank is never more than 3 feet in height, and it is much broken; we found in it, however, within the space of 30 or 40 yards, Wenlock shale and slabs of limestone on the west, just by the old quarries of the Hay Head limestone. East of this, for about 10 yards, there was coal-measure shale, with a bed of good coal nearly 2 feet thick, apparently in a nearly horizontal position; east of that again, for 5 or 6 yards, was a sandstone, exactly similar to that near Shustoke Lodge in lithological character, with similar calcareous portions, but, so far as we could determine, after an hour's hammering, destitute of fossils; and immediately east of that, dark red brown marls and shaly sandstone, belonging to the Permian rocks. In the next field to the east were the mounds of two old shafts in which coal-measures were said to have been reached at no great depth. At the Three Crowns Inn, 150 yards to the north, a two-foot coal had recently been found in sinking a well, dipping gently to the east. I believe these coal-measures to be merely thin outlying portions of those to the westward, lying unconformably on the slightly inclined edges of the Silurian rocks, and resembling in position the thin coal-measures found on each side of the Lickey ridge near the Colmers. There are some circumstances in the structure of this portion of the district which would incline us to the belief that the edge of the Silurian and Coal-measure rocks is here rather an old cliff, or other margin of denudation, than a fault. They are, however, explicable also if we suppose the Silurian rocks to have been slightly undulating, and the fault that traversed them likewise wavy, so that in some places it cut through slight elevations of the Caradoc sandstone, and the lower measures (leaving portions of them, now exposed at the surface, on the upcast side), while in other places it cut through higher beds which now abut against the fault, having the top of the Caradoc sandstone a slight distance beneath them. The discovery of Caradoc sandstone in this district beneath the Wenlock shale, in its characteristic and unaltered condition,—that discovery being due to Mr. Sharpe,—is interesting both in itself, and as confirming, were confirmation necessary. Sir R. I. Murchison's identification of the quartz-rock of the Lickey Hill, as a metamorphosed Caradoc sandstone.
[Note.—The term "Caradoc sandstone" is used here in its old signification,—possibly "Wenlock grits" might be the more appropriate term for these beds.—J. B. J. July 14, 1853.]
- Shustoke Lodge, also known as Walsall Lodge or Merrion's Wood Lodge: (Wikisource contributor note)
- See, for example, Hay Head Quarry. (Wikisource contributor note)
- The Three Crowns (per Ordnance survey 6-inch maps, 1888-1913): (Wikisource contributor note) )
- See: Caradoc Series. (Wikisource contributor note)