158 NATURE-STUDY LESSONS. 



12. Note the difference in the way in which they split. 



The tendency of a mineral to separate parallel to certain planes is 

 cleavage. 



13. Place both in water to find out wliich is heavier. 



14. Apply heat to each, and infer which can be melted 

 more easily. 



15. From the qualities you have tested infer the uses 



of each. 



XLIV. -LIMESTONE. 



A lens and hammer are needed for work connected with rocks and 

 minerals. 



This stone is widely distributed in Canada, and may 



be found almost everywhere in southern Ontario, either 



as boulders in the fields or in " place " along some 



stream, lake shore, or in some quarry. 



1. If a limestone quarry is in the neighborhood, visit 

 it and observe the manner in which the stone admits of 

 being readily taken out. 



This condition of layer on layer is called slratificalion and each layer is 

 called a stratum. 



2. Observe whether the strata are horizontal or not. 

 When not horizontal, the angle of inclination of the strala to the horizon 



is their dip. 



3. Observe the markings on the rocks to discover any 



remains resembling shells. 



These remains are caWei fossils. 



Observe whether the strata are continuous or if they are fractured. 

 If the strata are fractured, observe whether the opposite sides of the break 

 have been displaced. 

 The displacement of the layers on one side of a fracture is called a. fault, 



4. Can you scratch limestone with your finger-nail ? 



5. (a) Draw the point of a pocket-knife forcibly over 



a piece of limestone. Does the knife scratch 

 the stone ? 

 {b) From this infer which is harder, limestone or 

 steel. 



