155 



hand, Anotlier substance of this kind is o£ a red or 

 pink color, and appears as if it had been inlaid with 

 specks of gold. Although not valuable it is a prettj^ 

 stone. The crystaline rocks are those which were 

 formed in the presence of great heat, and they are 

 found to underlie all others. It should here be stated 

 that all rocks should be divided into two classes, the 

 stratified or those formed in layers. Aqueous rocks are 

 always of this form. The second class, unstratified or 

 those destitute of any regular arrangement. The 

 metamorphic rocks are those which by the action of 

 interior heat have lost their former stratification. The 

 aqueous rocks are those deposited as sediment by w^ater. 

 Igneous rocks are those which are ejected in a melted 

 form and afterwards cooled. These different kinds of 

 rocks are interesting for study and observation. The 

 origin of rocks is supposed to be as follows: while the 

 earth was still in a melted condition the water which 

 now covers the larger portion of its surface could find 

 no resting place, but hung over it either as huge un- 

 condensed clouds, or vapor. When a comparatively 

 thin crust had formed this moisture was condensed a>nd 

 fell in rain, and completely covered the earth in a deep 

 layer of boiling water. Occasionally the crust was 

 broken in places and some of the molten material 

 thrown up, upon which the water f orraed laj^ers in reg- 

 ular form of sidiment over the ocean's bed. When by 

 long cooling the crust had become thicker and firmer, 

 and formed into huge folds by the contracting strains, 

 portions were forced above the water and formed dry 

 land. During all this time the water had been arrang- 

 ing the looser materials into layers or strata, which lay 



