24: THE LEWIS BROOKS MUSEUM. 



the earth, it follows that Mineralogy, the science of mine- 

 rals, is a most important part of Geology, and forms the 

 starting point for the study of the composition and structure 

 of the earth. 



The composition of the earth has changed from time to 

 time, minerals have been formed, removed and replaced by 

 others. Hence Mineralogy gives the Geologist information 

 concerning, not only the present, but also the past condition 

 of the earth. 



The inhabitants of the earth, the animals and plants, 

 have not always been what they now are. Numerous 

 forms have made their appearance, undergone changes, and 

 passed away, to be succeeded by others of different character. 



Now these changes in the life of the globe are records 

 of changes in the earth, and of stages in her progress. As 

 such the Geologist must study them, and to do so he must 

 call to his aid the sciences of Zoology, Botany and Meteor- 

 ology. He must know how changes in the surface features 

 and climate of the earth can produce changes in living 

 forms. 



Botany and Zoology, applied to the explanation of ex- 

 tinct forms, constitute the department of Paleontology, a 

 most important section of Geology. 



Though this branch of the science does not admit of 

 many practical applications, possessing immediate economic 

 value, it is the most absorbingly interesting of all, as is 

 shown by the numerous band of devoted followers who pur- 

 sue it, at large cost, and with no hope of pecuniary return. 

 Its surpassing interest is due to the grand problems of life 

 and change, with which it deals. 



Paleontology gives to Geology, not only important 

 information concerning the past changes of the earth, but 

 furnishes the means also of establishing fixed points in her 

 career. She gives the data for dividing the column of sedi- 

 mentary rocks into periods, marked by the peculiar life 

 which prevailed on earth when they were forming. 



