Hunting Donshire. [Kelly's

6 HUNTING DONSHIRE. [KELLY'S damine, Dr. J. 1\Iitchell and Professor H. G. Seeley have Woodstone and Fletton. In the \"arious brick-pits south of appeared in the Geological Society's Proceedings and Peterborough the dark-blue clays contain large quantities Quarterly Journal. of fossil wood, either converted into jet or mineralized by The surface of the county is low and undulating, with a iron pyrites: it is sometimes found in masses of large size. gentle slope northwards towards the Fens. On the west, ha\'ing evidently floated about on the deep sea, at the Keystone Toll-house is 245 feet above the sea, El ton 107 feet, bottom of which the Oxford Clay was being deposited, Spaldwick gi feet, Chesterton 64 feet, and Peterborough until, becoming water-logged, it ~ank to the bottom and only 28 feet; Huntingdon is 45 feet, St. Ives 26 feet and was covered up. The teeth and spines of fishes also occur Fenny Stanton 42 feet respectively abm·e sea level. here. The same Oxford Clay extends southwards right In examining the geological features of Huntingdonshire, down by Huntingdon, past Kimholton and St. Neots, and if we begin in the north-west of the county, we shall find eastward by St. Ives into Cambridgeshire. In the Fen there the oldest and also the most varied rocks. d1strict deep trenches are cut through the surface peat and THE OoLITES.-Between Peterborough, Wansford and silt into the clay beds below, and the I at ter are then dug Elton, we ha\·e a very interesting expanse composed of and spread out on the surface. At H.amsey, near the several heds of the INFERIOR OoLITE, on the eastern or Railway station, the Oxford Clay was formerly dug and Huntingdonshire side of the Valley of the Nene. Crossing burnt for ballast, a use to which the clays of this formation the river at Wansford we find oursell""es on the- are frequently applied. At Ramsey Heights there are ( I.) ~{01·thampton Sand.-Following this bed southwards, several brickyards at work, the Oxford Clay being locally past the Mill, we get a fair section in a small pit at New termed "galt ; " in one of these peat is used for fuel. At Close Cover. Here at the top is some brown and yellow Forty-foot Bridge a band of hard rock 8 or 10 inches thick sand full of plant remains, with white sand underneath. is found at a depth of 15 feet. Ammonites Lambrrti is Returning, we can trace the same sands past Stibbington to common here. Connington and IIolme brickyards, and Water Newton, where, with some associated beds of clay, indeed the brickyards generally over the region we have they are dug in the brickyards. described, afford. other sections of the bluish Oolite Clays. From the Oxford Clav at St. Scots the remains of a large (2.) The Lincolnshi1·e Oolite Limestone.-In the Wansford new species of reptile ( PlP.siosau1·us E-r:ansi) has been, stone-pits we have some good sections of this fine bed, obtained. which fnrther north in Lincolnshire is 200 feet thick, and In the extensive excavations at St. J\·es we find a rather which is so largely worked for building purposes at the pale bluish-grey fine clay, with occasional calcareoru~ .con famous quarries at Ketton, Ancaster, &c. From the ""\Vood cretions, small crystals of selenite and lumps of pyrites: pit" at Stibbington, the late Dr. H. Porter collected about numerous species of fossils from these pits are shown in the forty species of fossils: at Water Newton brickyard there is 'Voodwardian Museum at Cambridge, including 19 species 4 feet of fine-grained oolitic limestone visible, with nodules of Ammonites; Gryphna dilatata i~ also most abundant. of ironstone resting upon it. Here we are evidently near the "thin end of the wedge," for eastward of this point CoRALLIAN BEos.-In the brickyards near St. Ives we this limestone bed dies out altogether. find one or two of those bands of impure limestone, which THE GREAT OOLITE.-All the four members of this occur in this district at the top of the Oxford Clay. Tbese series are present in Huntingdonshire. The lowest, ur (I) limestones, with an associated bed of clay ( Ampthill Clay!,. Upper Estum·ine se-ries, is clayey ; above it we have ( 2) the are the local representatives of the Corallian Beds, or so Great Oolite Limestone, then (3) the G1"eat Oolite Clays, and called "Coral Ilag," of which other exposures occur at lastly, another limestone band-the (4) Co1•nbrash: all of Upware, near Cambridge, and Stanton St. John's, neat> these come on one above the other, overlying the two beds Oxford. of Inferior Oolite described abo1·e. The Upper Estuarine The St. Ives rock is also tracp.able at High Papworth. series is dug for brick-making at Water .Newton, and is while a higher band was exposed in the rail way cutting ::~t. well exposed in the Sibson tunnel. At the western end of Bluntisham, and a lower one at St. Neots. the tunnel, near Wansford statiOn, the whole series of beds, UPPEU OOLITE.-Ti1e Kimerid_qe Clay.-The Coralliall from the Great Oolite Limestone down to the thin repre Beds being only traceable with difficulty, there is no very sentatives of the Lincolnshire Limestone and Xorthampton clear line of division b~tween the two great beds of the Sand, may be seen. Oolite Clays-the Oxford Clay below, and the Kimeridge Tile Great Oolite Limestone forms the steep escarpment Clay abo\"e. The Kimeridge Clay, however, only just of Alwalton Lynch, where it contains numerous bands of enters Huntingdonshire (in the south-east corner of the fossil oysters. The "Al walton marble" was former!y county) at Pop le Grove, about six miles east of St. N eots. dug her~, but the pits are now closed: the stone was a hard, It is a dark-grey clay, here about 100 feet in thickness, but blue, shelly limestone, which took an excellent polish, but only the lower layers enter Hunts, the main mass occurring was not very durable. There is a petrifying spring here, further P.ast, in Cambridgeshire. It is worked for brick which has formed a deposit of travertin, often encrusting making, and contains such fossils as Oatrea deltoidea~ tufts of grass, snail-shells, &c. and covering them up; the Ammonite.~ biple.x, &c. same beds are traceable round to Elton in one direction, LOWER CRETACEOUs FoR~IATION".-T/a; Lo1rtr (;l·een~and. and on the east are finely exposed in the railway cuttings -This interesting deposit is composed of brown or yelllH\" near .Hottlebridge. The Great Oolite Clays are often seen sands, the tint being due to the presen-~e of oxide of iron. resting upon the limestone; they contain bands of iron which is sometimes absent, when the beds are white : it, stone balls. forms a ra.nge of low hills which extends from Potton aml The Cornbrash is a hard, blue limestone when dug at any Sandy, in .Beds, by Waresley and past Gransden; it h~ depth, but it weathers light-brown at the surface; it is been worked for the valuable band of coprolites which i~ exposed in the valley of the Billing Brook, especially about contains. Water Newton Lodge, and is here very fossiliferous; it is very hard, and is used for road-metal; the top is usually EcONO:\!IC uKOLOGY.-The following particulars for 191:? marked by a band of large rugose oysters-Ostrea marshii ; are taken from the Government annual publication en it forms a light red soil. There is a small inlier of Corn titled "limes a71.d Qua1·.-ie.~. They do not, however, include brash between Stilton and Yaxley, which is brought up by returns from excavations which are less than twenty Je~t ia a fault. No fewer than 68 species of fossils have been depth:- found here, and the most delicate shells, often retaining Brick-cla~·, 539,720 tons; ¥alue £16,185. their pearly lustre, are found in a perfect state. i\"11mb~l' c~f 1Je1'9ons employed, 217. MIDDLE OoLITEs.-The Oxj01·d Clay.-This great clay l'LEISTOCENE FoRMATION : THE DRIFT. -The glaci<JJ deposit here, probably more than 400 feet thick, occupies deposit called the great chalky boulder-clay is of a bluish the county of Huntingdon to the exclusion of almost every colour, and is crowded with masse, of rock which often other rock : to the north-east it passes under the J<'ens, of exhibit the polished and scratched appearance characteristic which, however, it constitutes the substratum, rising above of glacier or ice-borne masses : it extends more or less over it in island-like masses here and there; but even in the the whole of the county, and is often of great thickness. rest of the district it is generally so co\"ered by the super Masses of chalk and flint are abundant in it, with oolitic Incumbent boulder-day and.gra\"el~, as to be seldom exposed, and liassic fossils, millstone grit, ~andstone, mountain even in the river Tallep. The land j; forms is mostly limestone, &c. ; it ~ecms t.o ha\·e been deposited by a great devoted to gmzing, although there is some woodland, while glacier pushing down from the north. of late years an increasmg area has been brought under the plough. RECF.NT FoRli[ATIO:Il.-The vallep gravels of the Xene are Of the hard, Fandy beds at the base of the Oxford Clay, of later date: near Elt(Jn they have been cemented together known as the Kellaway's Rock, there are no !!OOrl exposures.

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