24 LINCOLNSHIRE.

a large rugose speciEs of oyster-0111trea Jlm·.~hii. It forms of the Wolds the Lower Cretaceous beds extend northwards a red soil of no ~reat fertility, and is esteemed as furnishing on the east llide or the Wolds 11.s far as Belleau, but they hard road metal. are here covered over by Drift. The Lower Cretaceous­ strat.a of Lincolnshire are the equivalent, speaking· The region occupied by the Great Oolitl's and Cornbrash generally, of the L01cer Greensand of the counties further combined forms a narrow band from one to two miles wide, south. They may be sub-divided into ( 1) the Spil.~by Sand­ running north and south down Mid Lincoln'!hire, extend­ stone, which near the town of that name can be seen to re.Qt ing from St,amford by Castle Bytham, ~apperton and upon the KimmeridlrEl Clay; (2) the Cloxby Ironsto11e; (3) Blankney, to Bishop's Norton, beyond wh.ch the strata are Twlby Clay; (4) Tealln; Lime.~tone; and (s) the Cm·stone. only occasionally visible as far as the Humber. This region The total thickiJess varies from 200 feet hetween East Keal is characterized by a series of low, tlat-t(1pped bills, and and Candlesby to about So fpct near Caistor. The Car­ some admirable sections of the beds have been exposed in stone is unfo!'siliferons ; and by some geologists is placed the cuttings of the Great Northern Railway, as at Essen­ with the Uppel" Cretaceous Series. All the beds are o~· dine, Little Bytham and Ponton. marine origin, cont a.ining such fossils as Belemnites lattn"alis,. A mmon1tes beani, and P erna mulleti. At Hrinkhill there i.lf THR MIDDLE OOLITBS are represented in Lincolnshire by a stratum of iron pyrites, known from its yellow hue a& an extremely thick bed .of clay, which is very similar in " Brink hill Gold." app~arance to another bed of clay whieh lies upon it ; but this upper clay is prnved by its fossils to be quite a distinct The West Yorkshire Coal and Iron Company opened arr formation, belonging, in fact, to the L'pper OoJites. The iron mine in the m1ddle N eocomian beds at Acre House, lower bed is known as the O:r:fard Clay; it has at its base between Claxby and N ettleton. The existence of fragments certain hard SBndy beds called Kellaways H.ock,xo to 20 feet of iron slag, Roman pottery, &c., in this part shows that in thickness ; but the clay above is probably 400 feet thick the ore was known and worked in very early times. Prof.. in South Lincolnshire, where it underliLs and borders the Judd described the bed which was worked as a rock almost. western part of the Fens, extending {at the surface) from entirely made up of small and beautifully polished oolitic Dourn northwards by Helpringham, Sleaford, Bardney, grains of hydrated peroxide of iron. The earthy material~ and West Rasen to Wrawby, &c. The outcrop of the full of larger concretionary masses or ironstone, which was Oxford Clay varies in width from 8 miles between Sleaford at first thought to be equally valuable, was found to yield and Carrick to about 3 miles east of Glamford Briggs. so small an average pereentage of iron that it was not The basal Kellaways Rock has been exposed at Bourn. worked. J:<'ossils are n•1merous, especially a large shell Folkingham, 8leaford, east (jf Lincoln, and at Langworth, named Pecten cinctus. The ore contains much limestone. The characteristic fossils of the Oxford Clay include Am­ and is consequently well adapted for smelting, mixed w_ith -monites ornatus, A m. cordatus, &c., with Bdemnites orreni, the clay-ironstone from the coal measures : it was mostly B. ltastatus and (fryphma dilatata. The Belemnites are sent to Leeds for that purpose. 885 tons, valued at £177,. known to the country people as •• thunderbolts" and as were raised in x874, but the workings have since ceased. "fairy d<~.rts." UPPER CRETACEOUS FORMATION."'-Ordinary "white chalk" is one of the best known rocks in the 'south and Carallian Bed~r.-In Yorkshire, and also in Dol'Setshire &c., the Oxford Clay is separated from another great clay­ east of England, and gives its name (Latin, creta, chalk) to bed (the Kimmeridge Clay), which lies above it, by certain the beds associated with it. At its base, and resting upon beds of grits and limestoHes known as the Corallian series. the Carstone, we find a stratum which at once arrests In Lincolnshire there are no such hard bands at the attention by its colour, viz. :- junction (which is therefore difficult to trace), but their The Red Chalk.-This band, about 4 feet thick at place is occupied by black clays (15 to 20 feet m thickness), Hunstanton, is familiar to all who have ''isited the Norfolk containing crystals of selenite and septaria, in which the coast ; it is traceable all through Lincolnshire from near fossil shells Ost1·ea deltoidea and f7ryphrea dilatata both Gunby by Candlesby, Nettleton, Grasby, Barnetby and occur. These black Corallian Clays are named the Ampthill South Ferriby. Everywhere a cunous branching sponge, Clays, because they are well exposed near the town of Spon9ia parado:ric.J, is a common fossil, together with Amptbill, in Bedfordshire. lidemnites minimus: the Red Chalk is as much as :14 feet UPPER OoLITEs.-These are represented only by the thick in Mid Lincolnshire: in geolog;cal age it is the Kimmeridge Clay, which forms a broad band twche miles equivalent of the Gault Clay of the counties further so.uth. wide in the south of the county between Tattershall and Chalk.-Above the ''Red Rock" there are Horncastle, but greatly narrowed in the extreme north by The White several bands of pinkish chalk which have often been mis­ the overlap of the Cretaceous beds. It comes np to the taken for it. One such occurs near Louth. As we ascend western foot of the Wolds, and Bolingbroke~ Tealby, Mclton the chalk becomes harder, and, having resisted denudation Ross and Worlaby indicate its eastt~rn edge; it is above 6oo feet thick, and is exposed in numerous brickyards, in the better than the softer strata. which occur both aboye and cuttings o[ the Louth and Linc-oln railway, &c. At the top below it, now forms l'n almost continuous ridge along the of the Kimmeridge Clay there is. a very bituminous bed of western edge and top of the Wolds, being only cut through by Calceby Beck, the head-water of the Withern Eau. The aha~P, resembling that of the coal measures; early in the present century, much money was thrown away in conse­ chalk of Lincolnshire bemg much more covered by super­ quence, in boring for coal in the valley of the river Bain, ficial deposits than the hills of the North and South Downs. where these shales are well exposed. The Kimmeridge has not to the same extent the smooth, rounded, and Clay is very fossiliferous, and many fine specimens of gently swelling aspect of the latter : it has mostly been brought under the plough, and with very SBtishctory Ammonite.! alternan.~, with such bivalve shells as Thracia dep1·essa, T1·tgonia juddiana and Nucula menkei, have been results. collected near Market Rasen ; the shaly beds at J:<'ulletby and JJivi~Jiuns of the Chalk.-During recent years the minute­ West Ashby contain Ammonites biplex, Lingula ovalis, &c. and careful study of the Chalk undertaken by Dr. C. Harrois-, Dr. A. W. Rowe, Messrs. W. Whitaker, A. J. Jukes-Browne. JuRASSIC EPocH.-I he Oolites and the Lias are often G. W. Lamplugh and other geologists have proved that the grouped together under the joint name of "Jurassic," great mass of soft white earthy limestone (so well-known bel"'d.Use they are well displayed in the Jura Mountains, as "Chalk") which forms Salisbury Plain, the North and which di\·ide France from Switzerland. The Rhretic Beds South Downs, and which extends right up the east of Eng­ undoubtedly mark a depression of the old desert and ~alt­ land as the Chiltern Hills and the Lincolnshire and York­ lake region in which the' 'l}rias was formed, and as the shire Wolds, can-mainly by means of the different species depression cont-inued the Liassic strata were deposited in a of fossils which it contains, but also by the help of certain fairly deep sea, the shores of which lay to the east, north petrological variations-be divided, first, into three main and west. During Oolitic timts "tbi~ ~ea seems to have sections (Lower, Middle and Upper Chalk), and then stHI become clearer and warmer; and some of the limestones of further sub-divided into eleven "zones," each zone being this period are probably old coral reefs. characterized by certain species o( fossils one of which i!:i . chosen to give the name of the zone. In descending order THE CHETACEOUt! FORMATION.-The Chalk Wolds of these eleven zones are :- Lincolnshire are welt known ; but on their western slopes there are a series. of sandstones, ironstones and clays which Zone.~ of the Chalk. are nut so easily recognized. These constitute a sub­ division to which the term Lo'll'er Crtfaceous CT r I I Zone of Ostl't!ll lunata. Neoc~mian. is applied. We can trace them at intervals 10 , Btlemnitella rnucronata. northwards into Yorkshire, where they form part of the 9 , Actinocama.x quadrat-us. Speeton Cliffs, which overlook Filey Bay. In Lincolnshire Upper Chalk 8 , Marsu:pites testudinnrius. they crop uut from beneath the chalk near Elsham, and 7 , JJficra:.ier .::aranguinum. pass southwards by Caistor, Tealby, Scamblesby. Tetford, 6 , Micra.~er cortestudimn-ium. Hundleby and f:pilsby : curving round the south-east end 5 , Holaster planus.