POSITIONS OF THE DIFFERENT STRATA. 35 



of the Pyrenees, in the southern part of Cevennes, in the moun- 

 tains of Forez and Beaujolais, and in some parts of Vosges. They 

 form all the Hundsruck, Eiffel, and Ardennes and the southern 

 part of Belgium. They are met with in Hartz, in Saxony, and 

 different parts of Germany, Sweden, and Norway ; and they 

 abound in England as well as in the United States. They every- 

 where offer a matrix for anthracite. ' 



41. Geologists are not agreed as to the natural limit between 

 these strata and those of a more recent order, generally designated 

 under the name of secondary formation ; bu4; most authors con- 

 sider the period of transition to cease beneath the carboniferous 

 rocks and the coal measures. 



42. While the different stratified rocks we have spoken of were 

 in progress of formation, there were effusions of granite and other 

 igneous rocks on their surface, and these geological convulsions 

 have produced in the strata elevations and changes of direction, so 

 that many of them are raised up and are very much inclined and 

 in some instances almost vertical. It was during one of these 

 revolutions that the mountains of Westmoreland and Cornwall, in 

 England, were suddenly elevated ; a part of those of Brittany, and 

 Bigorre, &c., in France, of the Hundsruck, Eiffel, and Hartz, in 

 Germany, and many other mountain chains. The superior transi- 

 tion strata, which were formed subsequently to this convulsion and 

 rested on the edge of strata thus upheaved, were in turn dislocated 

 and raised up, and according to the observations of a French geo- 

 logist, Elie de Beaumont, this elevation appears to have been ante- 

 rior to the formation of more recent rocks than those we have yet 

 mentioned, and to correspond with the eruption of masses of igne- 

 ous rocks of the mountains of Vosges, known under the name of 

 ballons of Alsace and Comte. The elevation of the hills of Bocage, 

 in Calvados and several mountain chains in England, Germany 

 and Poland appears to have occurred about the same time. 



The following diagram (fig. 27), represents the several strata 

 we have described, in a horizontal position, one lying above the 

 other, and embraces the granite or plutonic rocKs below, next the 

 aqueous or metamorphic rocks, and above the whole, the transition 

 formation, consisting of the Cambrian, Silurian and Devonian Sys- 

 tems of strata. 



{ IVv..|iia.i Sys-ein-fi'g-ilg- F'?hes. 



Transition Rocks. < Silurian System 'JWils-Tii'olii es 

 / Cambrian System- Fo>-il-, polyrs 



Fig. 27. 



Metamorphic Rocks 



r Ar^illar 



.4 Mica-nc 



(. Gnei*. 



41. How is the transition separated from the secondary formation? 



42. What is supposed to have happened while the stratified rocks we** 



being formed 5 

 24* 



