BERKSHIHE.

GEOLOGY OF BERKSHlRE.

NATURAL HISTORY AND SCIENTIFIC SOCIETIEs.-'Vellington "Fields of East and West Ilanney and Drayton." Crossing College ~atural Science Society, near Wokingham : Annual the Ock at Abingdon, we can follow the Kimmeridge clay to report; Newbury District Field Club; Rmding Microscopical Radley and Bagley Wood. Of the fossils Ammonites biplex Society. is rather common and beautifully preserved; Ostrea deltoidea MUSEUM.-Newbury;\Iuseum. is very abundlnt. The clay is dug at several places for PUBLICATIONS Oj,' THE GEOLOGICAL SURVEy.-}If"aps­ brick making. Sheets: 7, Western part of London, St. Albans, 'Windsor, (4) Portland Sand.~There is a small outlier forming the Uxbridge; 8, Wokingham, Croydon, Guildford, Reigate; hill on which the village of Bourton is built; it is well ex­ 12, Newbury, Andover, Odiham; 13, Oxford, Reading, posed in a large quarry there. Wantage; 34-, Chippenham, Swindon. Quarter sheeet; THE CRETACEOUS SYSTEM.-This term is derived from the 45, S.W. Woodstock, &c.-Books -The Geology of parts of Latin' creta,' chalk, which is the best known and most con­ Berkshire and Hampshire, by J::Iristow and Whitaker, 3S. ; spicuous member. The Geology of parts of Oxfordshire and Berkshire, by (I) The Lower GI·eensand.-This is a bed of loose reddish Hull and Whitaker, 3s.; Geology of the London Basin, sand, often full of p3bbles and very variable in thickness. .At by W. Whitaker, 138. Fernham and Great and Little Coxwell it assumes consider­ IMPORTANT \\"ORKS OR PAPERS ON LOCAL GEOLOGY.­ able local importance, constituting the" sponge-gravels of 1856. Prestwich, Prof. J.-Gravel near Maidenhead in Faringdon; " here it is largely quarried for gravel, which which skull of )Iusk Buffalo was found. Journ. Geol. from its bright yellow hue is much sought after for walks Soc., vol. xii. p. 131. 1875. Rupert-Jones, T. & King, and avenues. From Baulking eastward to the Thames it C. C.-Sections of the Woolwich and Reading Beds at is not seen, being overlapped by the Gault, but there is an Reading. Journ. Geol. Soc., vo!. xxxi. p. 451. 188r. outlier north of SunningweU which forms a hilly trac:t ; it Herries, W. H.-Bagshot Beds. Geo. Mag. p. I7L make'> a light dry arable soil. (2) The Galllt.-This is a blue micaceous clay containing THE rocks of Berkshire have been very carefully studied hy occasional nodules of limestone; it runs as a band about one the officers of the Geological Survey. Complete geological to two miles wide between Ashbury and Stainswick to maps of the surface were published in 1860-61, and in the Uffington, where it turns due east and reaches through splendid memoir on the Geology of the London Basin, by I West Challow and SteVf\nton to Wittenham; its upper Mr. W. Whitaker, a very full account will be found of all boundary is well marked by a line of springs thrown out the strata except those which form the extreme north-west Iby the impermeable clay; fOl'ming a low plain at the foot corner. The Tertiary Beds of the south and east were first of the chalk escarpment it is seldom exposed in sections, described by Professor Prestwich in a masterly series of except in an occasional brick-pit; its thickness is about papers published between 1840 and 1860 in the Journal of 100 feet. the Geological Society: Professor Rupert-Jones has also (3) The Upper Greensand or Chloritic Series.-From written on the same subject. I Wittenham Wood past Wallingford to Aston Tirrell the As the longest axis of Berkshire extends nearly ea'lt and Ioutcrop of this rock is not less than five miles broad. west, while the different beds of rock run across it in a Following it westward through Hagborne, Didcot, East slantingdirection from north-east to south-'Vl'st we naturally I Hendred and Wantage it rapidly narrows, until at Childrey, expect to meet with a good variety of formations in the Sparsholt, Compton lleauchamp and Ashbury it only forms county, and this we shall find to be the case. From the the slope of the escarpment of chalk, which consequently absence of disturbances, however, and from the dip being becomes steeper as we follow it in this direction. Frequently gentle and coinciding with the general siope of the surface, the exact boundary is obscured by landslips. As the name the variety is not so great as might have been expected. implies, the rock is usually full of greenish grains. At We shall commence with the oUest rocks, which occupy Woolstone it is 60 feet thick, but above 100 at Didcot. the extreme north-west of the count~·. (4) The Chalk.-This is perhaps the best known rock in THE OOLITE. (I) The Oxford Clay.-Entering at Coles- England-lithologically speaking; it constitutes the central hill and Lechlade, and running east by Thrupp Common and most elevated portion of Berkshire. On the west the and Newbridge and north-east by Hinksey, "VVytham and main mass spreads across from Hungerford to Compton Oxford, we have the Berkshire portion of a tract of stiff clay, Beanchamp, a distance of 12 miles. The strike, or direction, which extends across the Thames into Oxfordshire and is here nearly east and west and continues so to the Thames. Gloucestershire. It contains frequent bands of limestone, The dip is to the south-east at a very small angle, from one nodules or septaria, is of It blue colour when dug at any to three degrees only. In the Routh the chalk dips under depth, but weathers yellow where exposed to the air; it the Tertiary beds of the valley of the Kennet, and rises up forms a low tract of land borderin6' the Thames for about further south at a sharp angle along a line from Inkpen to a mile or two on its southern side, and is of little economic KingscJere; at Inkpen lleac;:>n it attains an elevati(Jll of value. It is mostly in pasture; a boring at 'Vytham passed I,OII feet, the highest point reached by the chalk in the through 596 feet of Oxford clay. south of England. The total thickness in B2rkshire of this (2) The Coral Ra,q.-This term is applied to a series of great mass of white soft limestone is probablyahout 900 beds, claye~' and sandy at the base, of which the middle feet; the chalk was eminently a deep-sea deposit, for when portion is a rubhly oolitic lime3tone full of corals, capped we examine it microscopically we find it to consist in large in a few places by irony sands. The muddy sea in which part of the tiny chambered shells of foraminifera, being the Oxford clay was deposited must have cleared and very similar in composition, in fact, to the greyish-white shallowed, and in the warm waters coral reefs grew ir- ooze which numerous soundings have proved to form tll3 regularly, resembling those now forming in tropical !'leas. floor of the North Atlantic Ocean. Where present the thickness of the Coral Hag varies from The Lower Chalk has mady beds at the base abont 80 feet 10 to 30 feet, and it constitutes a ridge overlooking the thick, whosetop ismarked by a hard band called the Tottemhie valley of the Thames. Entering the county near Shriven- Stone. This lower division may be seen in the Great Western ham, we can trace it round Faringdon, ami thence it occupies Irailway cutting at, Wallingford Road station. Above it we a tract three miles wide north of the river Ock as far as get about 400 feet of chalk without flints, but containing Abingdon and Cumnor: at Wytham it rises as an outlim' marly partings which indicate the line of bedding: this to a height of 583 feet; it is largely quarrieLl for road division forms the compdratively low anl flat table-laml metal. The lower portion contains characteristic Ammonites; which extends from Moulsford and Streatley by Blewbury corals and spines and plates of se't-urchins occur in the and Chilton, nal"rowin~greatlyas it goes westward. l<\ ssils middle portion in large number;;;. arc not very numerous. but _1 mmo/lite.~ l'al'ians and Tlin'ilitl.~ (;:l) Kimmerirl,qe Cla.v.-Another thick mass of blue clay are characteristic. The top is formel by a hard cream­ with bituminous shales succeeds the coral rag; it forms coloured band-the Chalk Rock-some 8 or 10 feet thick, flat wet land from Shrivenham station to Long-cott. Passing which from its superior har:lness usually forms the top of thf'. under the well-known sponge gravels of Faring-don, it re- chief chalk escarpment. Thns we can trace it all along- the appears south of Shillingforcl and Stanford, and. forms the northern brow of Ilsley Common ana Childrey 'Warren;