Coal District of St, Etienne. 7 



much less inclined than the declivities of the primitive rocks 

 near them, Thus, multiplied observations prove, that this 

 state of things which can easily be imagined, has not been 

 distended by any catastrophe subsequent to its formation, 



3. Jn the numerous places where the immediate superposi- 

 tion of the coal measures on the primitive country can be ob- 

 served, the former is clearly seen to take all the curvatures 

 required by the uneven surface of the latter, without any 

 loss of continuity or fracture of the beds. Would appear-, 

 ances be thus, if the rocks anterior to the deposit, or the de-? 

 posit itself, had been subjected to shocks and disturbances ? 



4. A single coup d'ceil thrown over the atlas accompanying 

 the work from which this memoir is extracted, shews that, in 

 the widest part of the basin, the coal measures have entangled 

 the elevated points of the primitive country, it would be easy 

 by following up all the details, to give nearly the configura^ 

 tion of the rocks at present concealed, and to conclude that 

 no important change has altered it. 



We could greatly extend these considerations and fortify 

 our opinion by a greater number of facts, did not the fear of 

 passing the bounds we have prescribed ourselves deter us. It 

 is here the place to state, that the coal measures, surrounded 

 on all sides by primitive rocks, support, but over a small ex- 

 tent, the remains of a newer formation, torn away at the time 

 when valleys were last formed. Patches of it are found at 

 present only on the elevations of St. Priest and La Tour, si- 

 tuated near the river Furens, between St. Etienne and the 

 Loire. 



This formation is remarkable, as volcanic tufa and frag? 

 ments of basalt are embedded in a siliceous substance, which 

 has been deposited in horizontal beds on the coaj measures. 



This fact does not appear elsewhere in any part of the St, 

 Etienne district, the volcanic hillocks, found in the plain of 

 Forez, have no immediate connexion with the coal measures 

 qnder consideration. 



M, de Bournon has described the minerals of St. Priest and 

 }a Tour, and given a detailed list of the different accidents 



