ONTCHOTHERIUH. 



OOLITE. 



iaa 



with white pungent hairs. 

 M and pniu-vllate flower*. Tb corolla U yellow, 



than UM calyx, tubularly campanulate with rrflcxed 



U naliv. of Tauria, in tb* vicinity of the Bosporus. 

 T* mot U eimpU. blackish, and oovmrd with a red pigment, which 



Mate* rB*r viol*t oolow. 



AU uT*p*d* of thi* gwua, which 

 eitrecMlv baadeom* wbeo in UoMom. b<i 



exceed thirty in number, are 

 i liliiooin. but art not valuable on account 

 at any pionlhr properties. Hoik of them are native* of roelu and 

 aody place* in Europe and Am, and aniwrr well to grow in rock- 

 work or wall top*. They an abort-lived, and apt to rot They do well 

 however in pot* among other alpine plants, 

 (Don l>i(lilamyd{<tu* PlanU.) 

 E'KI 



VCHOTHE'KICIL 



OHYX [AOATE.] 



OOLITE, Uw characteristic rook of one of the great systems of 

 secondary strata. [OlOLOOT.] One of the pureat example* of Oolite 

 U the fine yeUow freestone of Ketton in Northamptonshire, which u 

 wbeily oompoeed of round grain* of concretionary itructure, adhrrent 

 by their cootifaow surface*, to a* to form a atone eaaily wrought 

 with UM chiaeJ. and of a durable quality. The Bath free atone U 

 Mother example, where the grains (often hollow) are connected by 

 irtarpond oaloareoaa matter; tbe Portland atone reaemblea the 

 former, bat contains diaaeminated or aggregated ailex ; and not to 

 extend Uw catalogue, much of the Lincoln-hire freestone U Oolite, of 

 which tbe round grain* are firmly compacted in a general baaia of 

 HjdalHaeil carbonate of lima. The reeembbmee of the grain* to 

 mall ova, or tbe roe of Babes, ha* given origin to the EnglUh term 

 Oolite (from tbe Greek U*, an egg)! and the German Bogenatein, 



a po**easing tb* oolitic character occur in different parts 

 of UM etrie* of strata, but nowhere very abundantly except between 

 UM lie* and the grreoaanda. Specimens may be found in the moun- 

 tan-liaestoo* at Clifton, Kirkby Lonsdale, tc,, and in the magneaian 

 limestone of Tockabir* and Derbyshire ; and in this Utter case the 

 grain*, Urge and distinct, show obviously the concentric lamination 

 which belungi to certain oolite* called Pisolites, and which may be 

 detected in nearly all with the aid of the microscope. 



At on* time it was supposed that the little round masses which are 

 ao nh*iarl*il*tiri of thi* formation were portion* of limestone which 

 bud gathered round various forms of minute fossil animals. It was 

 1 that these organisms were probably Foramiaifrra. Recent 

 ie investigations have however shown that these little round 

 are purely inorganic, and that they are formed in the some 

 manner a* the larger nodule* of th* magnesUn limestone. [MAGNESIAS 

 LimrroXK,] 



Tb* oolitic deposits are divided naturally in England into three 

 parta, tbe I'pper Oolite rating on tbe Kimmeridge CUy, the Middle 

 OoUto reprobating the Oxford CUy covered by the Coral Rag, while 

 UM Lower Oolite is more varied, being composed of numerous bands 

 of clay, sand, and limestone. 



Tbe I'pftr Ooliitt, called on the continent the PortUndian Group, 

 are, so fr aa the British Islands are concerned, almost entirely con- 

 fined in their development to the south of England, only that stratum 

 of day which usually form* tb* base of tbe group being exhibited in 

 Yorkiire, i> UM va of Pickering. 



Tbe group of strata containing th* Portland atone, and exhibited in 

 Portland Island, include* several Uyen of coarse earthy limestone, 

 wUcb rest on a bed of siliosou* sand, mixed with green particles. 

 TbU M called tb* Portland Sand, and sometimes attain* a thicknea* of 

 m much a* M feet in UM weet of tbe island, and form* a complete 

 |iUi into tbe underlying cUy. 



Above UM coarse limestones of tbe lower part, which usually con- 

 a* of alternate bard and soft Uy*rs to a tbickne** of 60 or feet, 

 tber* an thre. bed* of lerviceabU atone, interstratified with oUy.y or 

 aUieeons band*. Koenla occur in all tbes* strata ; but they are ran 

 In tkos* bed* of UM ton* which are worked to advantage for econo- 



M upper part of tbe Portland series there occur, a very inter- 

 bed, shout a foot in thicknea.. of a dark-brown sutxUiioe. 

 few much earthy lignite. Tbia bed, called tbe Dirt-Bed, seem* 

 to U matte ap of Mark lotn, which at some distant period nourished 

 UM root* of torn, fragment* of who** sterna are now found fotriliacd 

 MMMd tt. Wbrrrver tbe dirt-bed i. laid open to extract the tab. 



of trees occur, and they are placed 

 growing in a modern 



, J lEriHf"" 11 ** [" II <|U C " <* " <>POt, that tbe surface of 

 UM FMiMd toe*, at the Unntoation of tb. Oolitic period. mu*t have 

 bw for *MM time dry land, and covered with a forest ; and we have 



" ^"LTT^Tl " dn ~ 600 of * 1-rtod i" Uw thick- 

 M of tbe dirt bed. which ha* accumulated nor* than a foot of black 



. an a oo o ac 



-rU. Ic^Ud witb thewr-k of ite form* vegrtation. Tb.Wtul.r 

 ai a-ifona preawvaUoa also of thi. thin bed over a distance if ao 

 any tail**, U that tb. change from dry land to the state of a 

 >Ur lake or staary <!,.. h tbe nature of UM overlying rock 

 UM |*riod of dry land) waa not accompanied 



pvwrea to have 



by any violent denudation or rush of water, aince the loose earth, 

 together with the tree* which lay prostrate on it* nirface, must 

 inevitably bar* been swept away had any uch violent catastrophe 

 thru taken place." 



Tbe Kimmmdyt Clay is of a blue, slaty, or grayish-yellow colour. 

 It frequently contains a coiikiderable quantity of aileuite, or crytallised 

 sulphate of lime. It usually effervesces with acids, and exhibits hi 

 tolerable abundance both vegetable and animal impressions, although 

 its fossils are rarely in such good condition* as to be preservable in a 

 collection. It i* a bed of great thickness ; horizontal, or nearly *o, in 

 it* stratification; extremely persistent in its peculiar mineral and 

 fossil characters, but not very extensively developed either in England 

 or on the continent. The name, Kimmeridge CUy, has been applied 

 to it because it is well exhibited at Kiutiueridge Bay, and near the 

 village bearing the same name in the Isle of Purbeck. 



At this spot there are also found, alternating with the clay, certain 

 beds of highly bituminous shale, occasionally used for fuel, and locally 

 known as the Kimmeridge Coal. There are many beds of lignite 

 found in the Oolite*, but these are perhaps tbe most remarkable, next 

 to those of the low-out Oolitic deposit* of Yorkshire and North 

 America. 



Among the foreign rocks of this part of the oolitic period are 

 1st, the Calcaire de Blaugy, on the coast of Normandy ; 2nd, the 

 upper beds of the Jura, in Switzerland ; and 3rd, the Soleuhofen bed*. 



On the bank* of Uie Donetz, in southern Russia, there are bed* of 

 Oolitic Limestone of light-yellow colour, which appear to belong to 

 this division of the secondary series. 



The Middle Outila consist for the most part of a thick bed of 

 clay, called the Oxford Clay, widely expanded throughout England, 

 and met with aleo in the same form on the Continent, and a series of 

 overlying limestones, chiefly remarkable for the abundant remains of 

 coral found in them. 



The upper bedn of the Middle Oolitic Series are partly calcareous 

 and partly sandy, the former consisting chiefly of a very interesting 

 group of corals known under the name of Coral-Rag, and the latter, 

 the sandy beds, or calcareous grits, often more or less intermixed 

 with calcareous matter, and containing thin lamina. 1 of clay sometimes 

 passing into irregular bands of hard and tough marly rock. Thin 

 calcareous matter seems entirely due to the presence of crushed and 

 decomposed organic remains. 



It is chiefly in Wiltshire, near the towns of Calne and Steeple 

 Aahton, and in the surrounding neighbourhood, that the corals of the 

 Coral-Rag are found in greater abundance and perfection ; and this 

 part of our island, at the time of the deposit, has clearly exi- 

 the condition of a coral island in an open sea. The thickness of the 

 bed is about 40 feet ; Urge portions of it are frequently mude up of 

 the remains of a single species, and an earthy calcareous freestone, 

 sometimes used as a building-stone, and full of fragments of shells, 

 rest* immediately upon it, and U surmounted by a fine-grained ferru- 

 ginous sandstone, slightly oolitic in structure, and containing a few 

 fossils, marking the close of the Middle Oolitic period. 



In the north of England the contemporaneous bed is a calcareous 

 deposit, also containing corals, but (as at Maltou, in Yorkshire) 

 including a considerable proportion of the fossil remains of shells, 

 both bivalve* and univalves. Tbe bed never loses ite coralline 

 character, and may perhaps represent an imperfect coral reef, once 

 extending from the south-west of England to what is now the right 

 bank of the Humber. 



The Usford Clay is a very important member of the oolitic eerie*, 

 attaining a thickness of not less than COO feet, and spreading over a 

 great part of England more especially occupying the fen-districts in 

 the counties of Cambridge and Lincoln, which appear to be partly 

 caused by tbe union of this bed with tbe Kiuimeridge Clay, producing 

 a wide expanse of flat and undrained country. Tbe same deposits are 

 well seen at Weymouth ; and they cover an important part of the 

 Eait Riding of Yorkshire. The stratification throughout it nearly 

 horizontal and undisturbed, being conformable with that of tha 

 formations immediately above and below it 



The appearance of the Oxford Clay is that of a stiff polo-blue 

 argillaceous bed, containing a large proportion of calcareous IK 

 and a more or leas abundant mixture of iron pyrites. Numerous 

 organic remains are found in it, which are sometimes preserv^l in tlu- 

 clay iteclf, but more frequently form a nucleus, about which ii-mi 

 pyrites have aggregated. Those preserved in the clay have been 

 generally found in a very rotten condition. 



The Lbirtr Oolita admit of considerable subdivision in the British 

 Islands, but the details seem to be rather of local than gm. i.,l 

 interest; and though partially extending to Normandy, ore by no 

 means universal in other parti of Europe. [GKOl.ouv.J 



1. The Corubraah (the uppermost bed) consists of n variable thickness 

 of clays and andaloiirs, which ultimately pass into a thin rubbly 

 tone, touiih and occasionally crystalline. 



2. The Forest Marble, which connist* of carbonate of lime. 



3. The Ureat Oolite, consisting of a variable series of coarse shelly 



4. Tue Bradford Clay, consulting of a pale greenish clay, containing 

 a small proportion of calcareous matter and inclosing thin slabs of 

 tough brownish limestone. 



