Fig. 15.-General section of the Cotteswold Hills.

(Prof. A. C. Ramsay.)

feet of the highest member of the series. At Sarsden the thickness is about 20 feet; at Fawler, near Stonesfield, 10 feet; at Enstone there is only a trace; and along the valley of the Cherwell it is altogether absent.

The Inferior Oolite forms good building-stone at Dundry Hill and to the south of the Mendips; the quarries at Doulting,' those near Yeovil and at Ham Hill are well known. At Ham Hill the stone is chiefly composed of comminuted shells. It has also been worked at Stinchcombe, Wotton Underedge, and other places in the Cotteswold Hills.

The soil is reddish-brown and brashy; the character of the ground is hilly, and sometimes barren, but where the soil is deep it is fertile.

Dogger Series. Resting upon the Alum Shale (Upper Lias) of Yorkshire is the series known as Dogger.'

The Dogger? is a sandy and oolitic ironstone, but the series is sometimes taken to include not only the Dogger proper, but the grey and yellow (Blue Wick) sands which underlie it.

The Upper Lias seems to pass gradually upwards into the beds above, which are classed as follows:

Feet

.

Yellow sandstone and ironstones (Dogger) including Dogger the Nerinæa Bed (N. cingenda)

30 Beds. Yellow sards and Sandstone, with Terebratula Bed (T. maxillata)

20 to 25 Blue

Grey sands and sandstones, containing a Serpula Bed, Wick and Lingula Bed (L. Beanii).

20 to 25 Sands. Upper Lias (passage beds), Sandy shales yielding Ammonites striatulus

(Striatulus Beds).

.

1 This stone was used in the construction of Wells Cathedral and Glastonbury Abbey. ? It is not cercain whether the Dogger (sometimes termed the Scar of

N

2

The Dogger itself has been much worked for iron-ore. The magnetic iron-ore of Rosedale is worked in this series; and Prof. Phillips considers that this ore, and those of Thirsk and Kirkham, are the equivalents of the Northamptonshire iron-ores.

The Dogger is placed on the horizon of the Inferior Oolite, so that the sands below are homotaxeous with the Midford Sands.

Lower Shale and Sandstone (Yorkshire).

LOWER ESTUARINE BEDS.

This series, which rests upon the Dogger, comprises alternating beds of sands, sandstone, and shale, with oolitic ironstone, and much carbonaceous matter, and attains a thickness of 280 feet. The beds, as a rule, contain no marine shells, but many plant-remains.

The "Great Sandrock, 50 to 100 feet, occurs at or near the base of the series : it is largely used for building-stone.' Mr. Hudleston observes that the group thins out towards the south and west of the Oolitic area; it, however, constitutes a large portion of the Staintondale Cliffs, where, in certain layers of nodular ironstone, many species of ferns are nicely preserved. The beds appear in the cliffs from Robin Hood's Bay to Huntcliff.

Millepore Bed (Yorkshire). This bed, so named from the occurrence of Cricopora (Spiropora) straminea, occurs as a limestone in Gristhorpe Whitby) has received its name from the lines of nodules, so characteristic of it, or from the peculiar appearance which the rock assumes owing to the rourding off of the huge oblong blocks, produced by the arrangement of the jointing. (W. H. Hudleston.)

1 Whitby Abbey was constructed of this stone.

Bay; nearer Scarborough it is obliquely laminated and arenaceous, and it is still more sandy at Cloughton Wyke. Dr. Wright correlates the Whitwell limestones of the Howardian Hills with this bed, and the slaty limestones of Brandsby appear to be on the same horizon. It is from 12 to 30 feet in thickness.

It is continued in the Cave Colite and Lincolnshire Limestone, and, as Mr. Hudleston considers, may therefore, with the Whitwell and Crambeck Limestone, be the chief representative of the Inferior Oolite in Yorkshire.

The bed yields Lima duplicata, Gervillia Hartmanni, Pinna cuneata, Ceromya Bajociana, &c. Most of the fossils have been obtained from Sycarbam, near Cloughton Wyke.

Middle Shale and Sandstone (Yorkshire).

MIDDLE ESTUARINE BEDS.

This group of Shales and Sandstones (Block Sand rock), from about 40 to 100 feet in thickness, contains many plantremains, ironstone-nodules, seams of coal, and sometimes jet.

The thickest seam of Moorland coal varies from a few inches to 18 inches in thickness. Mr. Hudleston observes that it is of little economic value, but it is remarkable for its persistency over a very large area, extending from the coast inland as far as Castleton and Coxwold.

At Gristhorpe the plant-bed has yielded many cycads, and ferns such as Sphenopteris, Pecopteris, Neuropteris, &c., also Equisetites columnaris.

Scarborough Limestone. This deposit comprises a series of blue and grey limestones (= 'Grey limestone' of Dr. Wright), with occasional shales and mudstones, 20 to 60 feet in thickness.

The beds yield Belemnites elongatus, Avicula Braamburiensis, Gervillia acuta, Perna rugosa, Pecten lens, Pinna cuneata, Trigonia costata, Gresslya peregrina, &c. Many species have been obtained at Hundale.

According to Mr. Hudleston the beds are feebly developed at Gristhorpe Bay (8 feet), but make a better show at White Nab and in Scarborough Bay.'

Stoneclif* Wood Series.—This series, named by Mr. Hudleston, consists of sands containing towards the base and upper part intercalated beds and lenticular masses (potlids) of arenaceous and siliceous limestone; it is altogether about 30 feet in thickness.

The beds form a sort of escarpment facing the Derwent Valley. Some of the stone beds are used for building purposes.

The fossil remains, including Avicula Braamburiensis, Gervillia acuta, Perna rugosa, and Mytilus sublævis, seem to link the beds with the Scarborough Limestone.

Collyweston Slate.

· At Collyweston, near Stamford, certain fissile calcareous sandstones, or sandy limestones, which, after exposure, split up horizontally and form flagstones, have been quarried for roofing-purposes during the past four hundred years, and are termed the Collyweston Slates.

These beds overlie the Northampton Sands. The surfaces of the slates, as mentioned by Mr. Judd, exhibit the proximity of the shore, in ripple-markings, worm-tracks, and burrows, as well as by numerous plant-remains.

The fossils of the Collyweston Slates include Pecten pumilus, Avicula Braamburiensis, Pinna cuneata, Gervillia

1 Mr. Sharp considers these beds to be in all probability nearly synchronous with the Lincolnsbire Limestone (Inferior Oolite). Phillips placed them with the Great Oolite.