306 NATURE STUDY. 



than those of minerals. With plants, therefore, the 

 problem of correlation is comparatively simple. The 

 written descriptions of minerals and of experiments in 

 physics are much more stereotyped, show less individu- 

 ality, than the accounts of the environment, habits, life, 

 and structure of plants and animals. On the other 

 hand, the work in physics and chemistry may be much 

 more exact, more quantitative, and correlate much bet- 

 ter with arithmetic. 



The relation of nature study to geography was dis- 

 cussed in Chapter XIII. This determines largely the 

 choice of matter in minerals and physics during the first 

 four years of the child's school-work. 



As a basis or foundation for geography, we find most 

 helpful in the earlier work in minerals those, five or six 

 in number, most common in rocks, such as quartz, feld- 

 spar, hornblende, mica, calcite ; and a few rocks, such 

 as sandstone, shale, limestone, and granite, most abun- 

 dant as earth-making materials. The study in the ear- 

 lier years of water, air, and heat as earth forces (the 

 forces which are nearest to the little children, and whose 

 effects they can most easily understand) is the most use- 

 ful as a foundation for geography, and the best prepa- 

 ration for future work in physics. In connection with 

 these, such topics as soil-making or rock-disintegration, 

 the work of rain and streams and waves, and the for- 

 mation of valleys and hills and bays and points, that 

 is, the effects of the above forces on the materials, 

 fulfil the other aims of nature study, and prepare for 

 the best work in physical geography. 



