424 



MINERALOGY, 



Geognosy. 



(!eographi< 



c il distri- 

 bution. 



Granite, 



>icnite, and 

 porphyry. 



and terebratulite?, arc the most frequent, and along 

 with these are .sonic entrochites, encrinites, turbinites, 

 ammonites and belemnites. 



4. Geographical Distribution. It occurs, in Scotland, 

 near the Crook, on the road to Moffitt, and in other quar- 

 ters both to the south and north of the Frith of Forth. On 

 the Continent, it occu rs at Christian ia in Norway ; in many 

 places in the Hartz, as at Blankenberg, where there are 

 extensive marble quarries, which afford a marble equal 

 to that named rosso corallmo ; in Italy ; in the country 

 of Bareuth, in Saxony, where there are several beautiful 

 varieties, one of a black colour, with fragments of entro- 

 chi, which nearly resembles the ncro d'Epitto of the Ita- 

 lians. Werner remarks of this petrifaction, that it oc- 

 curs most frequently in black marble, while petrified 

 corals are most common in those of a red colour. In 

 the south of France, and in the Pyrennees, it is a very 

 abundant rock ; while in the north of France it forms 

 a part of the great transition zone which extends from 

 Flanders to the Hartz. The north side of the Alps, 

 from France to Hungary, is bounded by an enormous 

 deposite of this limestone. 



III. Granite, Sienile, and Porphyry. 



These rocks, which are so nearly allied to each other, 

 occur in considerable abundance in some districts where 

 the predominating rocks are greywacke and clay-slate. 

 The nearest point to Edinburgh where these rocks occur 

 is Fassneyburn, about 12 miles from Haddington, where 

 transition granite, and porphyry, and also sienite, are 

 met with. These rocks are also found in Galloway, 

 and in other parts to the south of the Frith of Forth. 

 To the north of the Forth we may mention the vicinity 

 of Macduff in Banffshire, as an example of transition- 

 granite. On the Continent, one of the most striking dis- 

 plays of these rocks occur in the vicinity of Christiania 

 in Norway, where the following arrangement was de- 

 tected by Von Buch and Hausmann. 



1. Gneiss. 2. Transition clay-slate and limestone. 3. 

 Granite. 4. Clay-slate and limestone. 5. Greywacke 

 slate. 6'. Flinty slate. 7. Sandstone. 8. Porphyry. Q. 

 Granite. 10. Sienite, with imbedded cryst-ils of zircon. 



In this series the gneiss is the undermost, while the 

 zircon-sienite forms the uppermost bed of the series. 

 The limestone, in some places, is white and highly crys- 

 tallized, and contains tremolite, epidote, garnet, blende, 

 &c. but more frequently it is black and compact, and 

 contains orthoceratites, some feet in length, along with 

 pect'nites, chamites, trilobites, &c. . 



Similar arrangements have been observed in other 

 parts of the world. 



IV. Gneiss, Mica-slate. 



These rocks occur in small quantity, associated with 

 greywacke and greywacke slate, in the alpine land to 

 the south of the Frith of Forth, and even in some dis- 

 tricts to the north of the Forth. An arrangement of 

 the same description is described by Brochant as exist- 

 ing in Switzerland. 



V. Serpentine. 



Serpentine. In some districts in the Alps, serpentine occurs in 

 beds in transition rocks. 



VI. Quartz- Rock. 



It occurs in beds and in mountain masses, along with 

 clay-slate and greywacke, not only on the Continent, 

 but also in this island. 



VII. Red Sandstone. 



Red sand- This rock, which is very nearly allied to quartz-rock, 

 (tone. 



One!?, 



mica. slate- 



Quartz- 

 rock. 



occupies the same position as that rock in the transition Ger.gr.oty, 

 series. T"*" 



VIII. Transition Trap. 



Ubergangstrapp. Jl'erner. 

 Transition Trap. Janicmm. 

 Amphibolite. Daubuisson. 



The transition trap-rocks are amygdaloid, greenstone, Transition 

 and basalt. These occur in beds and in imbedded masses tra P- 

 in Dumfries-shire, and other transition districts in the 

 south of Scotland. In England they occur in beds 

 along with the alpine limestone, as in Derbyshire and 

 other districts. In Ireland it forms beds also in a lime, 

 stone which appears to belong to the transition series. 

 The trap-rocks of Oberstein, on the Rhine, of V eight- 

 land, also belong to the transition class. 



IX. Gypsum. 



Transition gypsum, according to Brochant, is ge- Gypsum, 

 nerally white, very fine granular or compact, and con- 

 tains particles of calc spar, scales of mica and talc, 

 and portions of rock-salt and of sulphur. He refers 

 the gypsum of Pesey to this class ; also that of Brigg in 

 the Vallais, which is covered with a granular micaceous 

 limestone, and also the deposite in the Val-Canaria. 

 The transition clay- slate of Salzburg also contains beds 

 and imbedded masses of gypsum. M. Von Charpentier 

 is of opinion, that the saliniferous gypsum of Bex is si- 

 tuated in beds in a transition limestone. 



CLASS III. SECONDARY OR FIXCTZ ROCKS. 



FIcetz gebirge. Werner. 

 Secondary, or flcetz rocks. Jameson. 

 Terrain Secondaire. Daubuiston. 



Secondary rocks, in the regular succession, rest on Secondary 

 those of the transition class ; and sometimes the older or flottz 

 rocks of the series, alternate with clay- slate and other rocks - 

 members of the preceding class. They are less crys- 

 talline than primitive and transition rocks, and are 

 particularly characterised by the number, variety, and 

 abundance of fossil organic species which they contain. 

 The principal secondary rocks are, sandstone, limestone, 

 gypsum, and trap. 



We shall now describe the different formations of these 

 sandstone, limestone, gypsum, and trap rocks, begin- 

 ning with sandstone. 



1. Sandstone. 



This rock is formed of angular or roundish grains Sandstone, 

 of different minerals connected together by means of 

 a basis or ground, or immediately joined without any 

 basis. When the grains are not larger than a hazel- 

 nut, the compound is simply named sandstone, but 

 when they exceed that magnitude, they are deno- 

 minated conglomerate, if the masses are roundish ; 

 but breccia, if angular. Sandstone is divided into 

 three kinds, named siliceous, araitlaceotts, and marly or 

 calcareous. In the siliceous kind, the particles are con- 

 nected by a ground or basis of quartz ; in the argillaceous 

 by a basis of clay, which is sometimes h'ghly impregnat- 

 ed with red oxide of iron, and gives a red cast to the 

 whole rock ; and the particles in the marly or calcareous 

 kind, are set in a marly or calcareous basis. 



The following are the formations of sandstone : 



I. First, or red sandstone, with the coal formation. 



II. Secind, or variegated smd^one. 



III. Third sandstone, or quart/.y sandstone. 



IV. Fourth sandstone formation. 



