Cretaceous Strata.
Bishop Stortford.—The waterworks and well are situate west of the town, near the farm buildings known as Marsh Barns. The shaft is 160 feet deep, the bore-hole 140 feet. The following is a section of the strata;—
| Feet. | |
| Boulder Clay | 17 |
| London Clay, 54 feet;— | |
| Brown Clay | 14 |
| Black Clay | 2 |
| Black Sandy Loam, with iron pyrites | 12 |
| Black Clay, with lignite | 11 |
| Dark Grey Sand, with large pieces of sandstone and shells | 15 |
| Reading Beds, 451⁄2 feet;— | |
| Black Clay | 2 |
| Brown Clay | 20 |
| Light Brown Sand | 01⁄2 |
| Variegated Sand | 18 |
| Brown Clay | 4 |
| Flints and Pebbles | 1 |
| To Chalk | 1161⁄2 |
| Chalk | 1831⁄2 |
| Total | 300 |
The water rises to within 140 feet of the surface of the ground. The yield is 10,000 gallons a minute; only 25 gallons a minute from the bore; the rest from the headings driven north and south respectively at a depth of 154 feet.
Braintree.—The well sunk for the Local Board is in a field near Pod’s Brook. The shaft is 8 feet in diameter, steined with 9-inch steining, and carried down 55 feet, the remainder of the well being bored. Strata;—
| Drift, 14 feet;— | Feet. |
| Sandy Gravel | 5 |
| Drift Clay | 9 |
| London Clay, 136 feet;— | |
| Clay, with sand, shells, and septaria, the bottom part more sandy | 126 |
| Dark Sand, with a few shells, yielding much water | 10 |
| Reading Beds, 45 feet;— | |
| Mottled Plastic Clays, getting more sandy lower down, and with specks of chalk | 44 |
| Coarse Black Sandy Clay | 1 |
| Thanet Sand (?), 33 feet;— | |
| Light-coloured Sands, firm and hard, getting darker and more friable lower down | 20 |
| Light-coloured Sands, firm, changing to coarse and dark | 13 |
| To Chalk | 228 |
| Chalk, with much water, rising to about 12 feet from the surface | 17 |
| Total | 245 |
The level of the ground is 140 feet above the sea-level; water stands 29 feet deep; yield about 11,500 gallons an hour.
Brighton.—This town has always been supplied from wells sunk in the chalk. One well is sunk near the Lewes Road, and has a total length of 2400 feet of headings driven in a direction parallel with the sea, and at about the coast-level of low water. These headings intercept many fissures and materially add to the yield.
A second well was sunk in 1865, at Goldstone Bottom, and headings driven to the extent of about a quarter of a mile across the valley parallel to the sea.
Goldstone Bottom is a naturally formed basin in the chalk, the lowest side of which, nearest the sea, is more than 60 feet higher than the middle or bottom of the basin. The water is obtained as at Lewes Road, from fissures running generally at right-angles to the coast-line, but they are of much larger size and at far greater distances from each other; whereas at the Lewes Road well it is rare that 30 feet of headings were driven without finding a fissure, and the yield of the largest was not more than 100 to 150 gallons a minute. At Goldstone nearly 160 feet were traversed without any result, and then an enormous fissure was pierced which yielded at once nearly 1000 gallons a minute; and the same interval was found between this and the next fissure, which was of a capacity nearly as large. The total length of the headings at Goldstone Bottom is 13,000 feet. The yield from each well is about 3,000,000 gallons daily.