428 



MINERALOGY. 



Geognosy. Coal It sometimes contains beds of coal, but these 



are in general so thin, as to be of no value in an econo- 

 mical point of view. 



Geognostic Situation. It rests upon the upper oolite, 

 and is covered by the chalk formation. 



Geographical distribution. It occurs abundantly in 



England, as in Wilts, Dorset, Sussex. Devon, Oxford, 

 Isle of Wight, Surrey, &c. And on the Continent of 

 Europe it is met with, both in Upper and in Lower 

 Saxony. 



Coal. 



Geognostic 

 situation. 

 Geographi- 

 cal tlistri- 

 lion. 



G -os>ncslical position. In what is called the regular GeAgnosy. 



succession, it oon.es immuliiitoly alter the old red sand- ' 



stone, and therefore rests upon it. 



Geographical <Hsll-;>l<or,. it abounds in the north 

 of England, also in Derbyshire, Wales, and Gloucester- 

 shire. 



Observations. It is said to occur sometimes in clay- 

 slate, and also in the coal formation. If this, statement 

 be correct, then probably the c.-al formation, red sand 

 stone, and this limestone, belong to the transition 

 class. 



Fourth 



sandstone 



formation. 



Secondary 

 or fleets 

 limestone. 



First se- 

 condary 

 limestone. 



Characters. 



Stratifica- 

 tion. 



Caves and 

 caverns. 



Chert and 

 quartz. 



Peu-ifac, 

 lions. 



Subordi- 

 nate beds. 



Metallife- 

 rous mine- 

 rals. 



Geognosti- 

 cal position. 

 Geographi- 

 cal distri- 

 bution. 



' Obierva- 

 ' tions. 



IV. Fourth Sandstone Formation. 



This formation is associated with the rocks that rest 

 upon chalk, and will, therefore, be described along 

 with these. 



II. Secondary or Fleets Limestone. 



The limestones of this series are more compact and 

 less translucent than those of the transition class ; and 

 further, they abound rouch more in organic remains of 

 different kinds. The following are the formations 

 -which hav been enumerated by authors, viz. 



I. First Secondary Limestone. 

 II. Second Secondary Limestone. 



III. Third Secondary Limestone. 



IV. Fourth Secondary Limestone. 

 V. Fifth Secondary Limestone. 



I. First Secondary Limestone. -Jameson. 

 Premier formation du Calcaire Secondaire. Daulidston. 



Alpine and .Jura Limestones of German and some 

 French Geologists, Mountain Limestone of Eng- 

 lish geologists. 



Characters. The colours of this limestone are grey, 

 blue,and black. Itslustre varies from glistering to dull; 

 the fracture is splintery, or granular foliated ; and it is 

 opaque or translucent in the edges. Some of the va- 

 rieties are stinkitoue, while the black varieties are those 

 known under the name lucullile, and both these, when 

 pounded, emit a very disagreeable smell. 



It is distinctly stratified, and the strata are some- 

 times undulated and contorted. 



Caves and caverns are not unfrequent in this forma- 

 tion, and extensive fissures frequently traverse it, which 

 either reach to the surface, or extend to a greater or 

 less distance under ground, and afford channels for 

 great springs and subterranean rivers. 



It frequently contains imbedded portions and beds 

 of Lydiau stone, of quartz in the form of chert, which 

 is either of a grey or black colour, and very much re- 

 sembles, the flint in chalk in the various relations it 

 bears to the limestone. 



Petrifactions are not unfrequently met with in this 

 formation ; and the following are the kinds which have 

 .been found in England, viz. eiitrochil.es, tubeporites, 

 vnivrjnite.s cornliitus, niadrcporitcs, ammonites, pecti- 

 nitcs, orthom-acitcs, &c. 



Si;li<fnluiale beds. These arc amygdaloid, greenstone, 

 tr:>p tuff, and basalt ; also sandstone, magnesian lime- 

 stone, slate- clay, bituminous shale, coal, and clay. 



Metalliferous .mineral*. This forntatiqn in some dis- 

 tricts, as in the north of England and in Derbyshire, is 

 particul ,'irly abundant in ores of different descriptions. 

 The lead mines of Northumberland and Durham, and 

 the lead and copper mines oi' Derbyshire, are situated 

 in rnpuntain limestone. 



Second se- 

 condary 

 limestone. 



II. Second Secondary Limestone. Jameson. 



Erster Floetz Kalkstein. Werner? 

 Magnesian limestone of English geologists. 



Characters The colours of this limestone are yellow, Characters. 

 and sometimes brown and grey. It is generally small 

 granular, and glimmering or glistering. One varietv is 

 flexible. It contains about 20 per cent, of carbonate of 

 magnesia. Its surface is, in many places, covered with 

 a poor herbage, uncommon in limestone, which is said 

 to be owing to the magnesia, -which is known to be 

 unfavourable to vegetation. 



Petrifactions. Organic remains are found in it, such Petrifac- 

 as madreporites, encrinites, product!, and fishes. tions. 



Geognoslic Position. It rests upon the .coal forma- Geognostic 

 tion, and sometimes alternates with new red sandstone, P osition - 

 and with a breccia composed of angular portions of 

 sandstone and limestone, cemented by magnesian lime- 

 stone. When it comes in contact with coal it deterior- 

 ates it. It frequently contains imbedded balls of foetid Imbedded 

 limestone, from the size of a pea to two feet in diameter, limestone, 

 and which Jiave a stellular radiated structure. The 

 limestone, containing these balls, is generally soft, mar- 

 ly, and magnesian, although the balls themselves con- 

 tain no magnesia. It forms lulls in some places 600 

 feet high. 



Geographic Situation. It abounds in some districts Geographic 

 in England ; thus it extends from Sunderland to Not- situation, 

 tingham ; the coal formation near Whitehaven lies un- 

 der it, and the same is the case in Derbyshire. 



III. Third Secondary Limestone. Jameson. 



Muschel Kalkstein. Werner? 

 Oolite of Bncliland 

 Lias and Oolite of others. 



Third 



secondary 



limestone. 



Geognostic Situation. This formation, according to Geognostic 

 Mr. Buckland, is divided into the following principal situation, 

 members : viz. Lower oolite, including the Liat limestone. 

 2. Middle oolite. 3. Upper oolite. The first or lower 

 oolite rests upon the variegated or new red sandstone, 

 and the upper oolite lies immediately under the third 

 sandstone-formation. The following is Mr.Buckland's 

 account of this formation. 



1. Lctver oolite. The lowest member of this portion Lower 

 of the series, or that which rests upon the new red oolite, 

 sandstone, is the lias, which is a blue, grey, or white ar- 

 gillaceous limestone, disposed in thin beds, in a bluish- 

 grey slaty marl, or clay. It rarely contains chert, more 

 frequently various petrifactions, such as ammonites, 

 pentucrinites, phigiostomitcs, ostracitcs, and occasionally 

 remains of crocodiles, as near Lymc, in Dorsetshire. 



Geographic Silualioii.lt extends from a little to the Geognostic 

 west of llchester, in Somersetshire, by Bath and Glou- situation, 

 cester, nearly through the centre of England, and ter- 

 minates a little beyond Lincoln. A lew miles beyond 



