MAKING THE ROCK BOTTOM. 1 5 



In fact, it is suspected by geologists, for example, Pro- 

 fessor Crosby, that our granite may be made up of some 

 of that sea bottom melted over and metamorphosed. 



There was plenty of time and plenty of heat and plenty 

 of moisture and plenty of pressure down there. 



For years and for ages the process of granite forming 

 was continued. The grains of quartz and feldspar and 

 hornblende, so distinct as to give meaning to the name 

 granite (grain rock), came into shape very slowly. For 

 many years the heat remained about the same, and the 

 little molecules of each kind of mineral clubbed together 

 by a mutual affinity so that there were enough to form 

 quite a respectable crystal of each before the whole cooled 

 off and so put a stop to their gathering. 



The feldspar seems to have got the start of the others 

 and assembled in groups according to the law of its 

 crystallization, with good square corners a quarter of an 

 inch long, and longer in many cases. The black horn- 

 blende was gathering at the same time, and there were 

 many cases where a few molecules could not reach a 

 larger group of their own companions because of the feld- 

 spar that surrounded them, and they had to form their 

 little crystals inside of the others. The quartz had to take 

 what room and shape there was left for it, in spite of the 

 fact that it was so bulky. It forms what is called the 

 magma for the other crystals, instead of taking the beau- 

 tiful shape of a six-sided prism and pyramid such as free 

 quartz naturally assumes. 



Inside of this quartz are cavities containing water, 

 invisible to the naked eye, so small as to number a thou- 

 sand millions to one cubic inch in some places. 



There are several other minerals to be found in small 

 quantities mingled with these three fundamental constit- 

 uents. 



Scales of mica, both white and black, are found in 

 places ; little cubes of iron pyrite are so plentiful in some 



