



INTRODUCTION. 



XXIX 



said to form a shield. When the superior strata have the 

 same direction with the fundamental rock, they are said to 

 be conformable with it ; but when the direction is different, 

 they are called unconformable. Sometimes they are simply 

 unconformable, as differing only in direction j but when in 

 addition to this they pass over the terminations of the inferior 

 rock,, they are said to be unconformable and overlying. 

 Strata may also be strait, form a mantle around the inferior 

 rock, cover its extremities in the shape of a saddle ; or, 

 when concave, assume the form of a bason or a trough. 



Considering Mr. Jameson's work as notes taken during 

 Mr. Werner's lectures, it may be assumed that this illustri- 

 ous mineralogist then proceeds to consider the succession of 

 the different formations. Those rocks which are always 

 found inferior, are called Primitive ; and have a crystalline Primitive, 

 appearance, intimating a chemical solution, when the water 

 stood very high over the surface of the earth. The next 

 class is called Transitive ; which, though chiefly of chemical Transitive, 

 composition, exhibits also mechanical sediments and petri- 

 factions. The third class consists of Stratified rocks, styled 

 by Werner Floetz, signifying that they are in flat or hori- 

 zontal layers or beds; a stratified rock implying that the 

 strata are of one and the same substance j while the Floetz, 

 or rocks in layers, often present beds of different substances. 

 But this distinction is not of such utility or importance as to 

 necessitate the introduction of a barbarous word ; and if 

 stratified be not precise, we may use stratiformed with Dau- 

 buisson. The Alluvial and Volcanic rocks form the last 

 divisions. 



It is to be regretted that the examples and facts are not 

 sufficiently numerous, but even the primitive rocks seem all 

 to be regarded as stratified, except granite, which is assumed Granite, 

 as the universally radical rock. In the Alps, Saussure has ob- 

 served that the granite presents marks of stratification. 

 Gneiss is also found under primitive granite ; and Mont Rosa, 

 nearly equal in height to Mont Blanc, consists chiefly of 

 gneiss and other stratified rocks. After long and diligent 



Floetz. 



