Geological Collectio7is. 



256 



composed of fragments of these two rocks, and the secondary deposits which 

 cover it, from the magnesian to the Jura limestone, seem to occupy the level 

 at which they were deposited by an ancient sea. 



Fossil Tree in the Coal Field near Dalkeith In cutting a water level 



about ninety fathoms down the gangway at Brian's farm, in the coal field 

 belonging to the Marquis of Lothian, a fossil tree has lately been discovered. 

 It is standing in a vertical position. Only a small portion of the stem has 

 Sas yet been exposed. That part now visible leaves room to conclude that 

 its height is very considerable. The portion already exposed is about seven 

 feet high. The bottom diameter about three feet. The class to which this 

 plant belongs is the vascular cryptogamic. It is a Sigilluria. They who are 

 conversant with the botanical history of fossil plants will easily perceive the 

 marked difference between those belonging to this class and the coniferous 

 plants of the same epoch, whose internal structure is in as beautiful perfec- 

 tion at this day as the various pines which now grace our hills and valleys. 



Coal Formation of Mid-Lothian — In our last Number we gave an extract 

 from a paper by Mr Dunn, on the edge seams of this formation. The 

 annexed wood cut will give a tolerably correct idea of the whole field, as 

 described 1^ Mr JBald in the Scotsman newspaper some time ago. 

 ■■'■ -^ii'joi lo uoinoq ;jl(Jiii'>b 



afl()o\y»x) a^ Isvjr iuA» fail i« 



■f ll ' l! U' lf JlU I UU lil t 



r is the Roman camp hill ; n is the north basin between it and Gilmer- 

 ton. The other basin is to the south between it and Ford. The upper line 

 is the surface of the ground. The double hatched line represents the 

 limestone bed buried under the coal strata in the two basins rising up through 

 it at r, cropping out at g Gilmerton, andy Ford. Dotted lines represent parts 

 supposed to be washed away. 



In the Mid-Lothian field, there are twenty-seven beds of edge coal ; but 

 above these, in the north part of the basin, there are six other beds found, 

 which lie in a position almost horizontal, and are called the Flat-coal, h on the 

 section. The relative situation of these is shewn, by two horizontal lines, in 

 the north basin. They are worked at Edmondstone and Sheriff- Hall, and 

 supply most of the coal which comes to Edinburgh from the Mid- Lothian 

 field. They are not found to the westward of Sheriff- Hall, because a 

 gi-eat slip occurs here, which, having thrown up the strata on the west side 

 a great many fathoms, the flat-coal beds, with the interposed rocky strata on 

 that side, had most probably been washed away by those great currents and 

 floods which have left so many traces of their agency on the earth's surface. 

 The flat-coals existing, are perhaps merely the remnants of larger masses, 

 the bottoms, or lower parts, of basin-shaped strata, of which all the upper, 

 or edge parts, have been swept away. 



Number of Mineral Species found in Moravia and other Countries. — In 

 Moravia, so poor in mines, there have been collected, in a space of 413 

 square miles, 111 mineral species, and 643 varieties. This is three more 

 than have been found in Bohemia, which is much greater in extent ; eleven 

 less than Great Britain has produced, eight more than Sweden, and nine 



