﻿HAUSMANN ON THE COAL-FORMATION OF LEON. 13 



cult to be determined from the imperfect state of the fossils. From 

 the mineralogical condition of the rocks, Mr. Pratt considers the latter 

 view not improbable. 



The manner in which these highly inclined beds of coal in Leon 

 are squeezed in between these similarly highly inclined transition 

 rocks is most remarkable ; and reminds us of the analogous relation 

 of the coal on the western edge of the Black Forest, between Offen- 

 burg and Lahr, to the masses of gneiss which seem to inclose it. As 

 a superficial observation would induce one to believe that in that in- 

 stance the coal was interstratified with gneiss ; so here one is inclined 

 to believe that the coal-formation of Esla is a member of the transi- 

 tion rock in which it seems intercalated, did not the very different 

 nature of the rock and the characteristic coal fossils which it contains 

 forbid the conclusion. The arrangement of the coal strata also proves 

 that their deposition took place when the beds of the older rock 

 which bounds them were not in their present position, and that the 

 upheaving of the transition rocks and of the coal was simultaneous. 

 On the probable cause of this upheaving the district in question 

 throws no light. If in many localities the rise of plutonic masses 

 may with probability be appealed to as the lever which has changed 

 the position of strata, yet in this case the manner in which these in- 

 considerable plutonic rocks occur (which, according to Mr. Pratt, 

 belong to the family of Greenstones), does not entitle them to be so 

 regarded. 



An extraordinary abundance of iron-ore is found in the hills form- 

 ing the northern boundary of the coal- formation, especially in that 

 part which is clearly Devonian, and also in that which is probably of 

 Silurian age. The iron is in the states of oxide and of hydrated per- 

 oxide, and occurs both in sandstone and in limestone. Deposits are 

 found extending over miles of country, and have been proved to be of 

 a thickness of 40, 60, 80, and even 100 varas. The sandstone often 

 contains 20, 30, 40 per cent, of iron, and even more. The limestone 

 is usually poorer, but offers great advantages as a flux for smelting 

 the ore. Thus it appears that the country through which the Esla 

 flows contains an inexhaustible store of iron, which can readily be 

 made serviceable, since there is in its vicinity so extraordinary a pro- 

 vision of coal. Mr. Pratt is of opinion that the oxide of iron was 

 not deposited contemporaneously with the sandstone and limestone in 

 which it occurs, but that it has been introduced at a later period by 

 plutonic agency ; a view which I adopt the more readily, as I had 

 arrived at the same conclusion from the study of similar deposits of 

 iron in Germany*. 



The chalk formation which is widely distributed in many parts of 

 Spain, appears in the vicinity of the Esla with its different members. 

 From the researches of Mr. Pratt, granitic detritus appears to have 

 furnished the materials of the lowest beds. They consist of sand- 

 stones and conglomerates, more or less consolidated, with a basis of 

 kaolin. This substance sometimes occurs so pure that it is adapted 



* Ueber die Bildung des Hartzgebirges. Abhand. Konigl. Gesellscb. Wissensch. 

 zu Gott. I. S. 375, 412, 425. 



