ORGANIC REMAINS. 21 



LESSON II. 



ORGANIC REMAINS. Fossils How produced. 



FIRST GEOLOGICAL EPOCH. Primitive Rocks Granite Gneiss 

 Mica- Schist Argillaceous- Schist. 



SECOND GEOLOGICAL EPOCH. Transition Formation Cambrian 

 System Silurian System Trilobites and other animal 

 remains Devonian System Fossil Fishes Fossils limits 

 of the Transition Formation Strata changed in Position by 

 geological Convulsions. 



1. We find entombed in the different strata of the crust of the 

 globe a great quantity of the remains of organic bodies, which at 

 different epochs have lived on its surface. Those which exist in 

 the present formations, and which have been deposited since the 

 last great revolutions of the earth, generally preserve their primi- 

 tive composition ; but those which have been found in the more 

 ancient strata have been altered in their nature, and passed into 

 the fossil state ; the gelatinous, fleshy, or ligneous portions, which 

 concurred in their formation, have in part disappeared, and have 

 been more or less replaced by stony particles. By the term fossil 

 (formed from the Latin, fodio, I dig) is meant any organic 'body, 

 or the traces of any organic body, whether animal or vegetable, 

 which has been buried in the earth by natural causes. 



2. In general, it is the hard parts, those that are capable of ] ong 

 resisting decomposition, which alone undergo this kind of altera- 

 tion ; such as bones, shells, and scales, for example. We never 

 find flesh, nor nails, nor soft fruits, nor other analogous bodies, in a 

 fossil state. Sometimes even these hard bodies disappear, and 

 leave merely tracts of their existence in an impression or print in 

 the rock that enveloped them. 



3. The organic remains which are found in the most superficial 

 and most recent strata of the crust of the earth, belong in part to 

 species which still exist; but most fossils are derived from ani- 

 mals or plants which have not existed since a period anterior to 



1. In what respects do the organic remains found in the most ancient 

 formations differ from those found in the more modern strata ? What is 

 meant by the term fossil ? 



2. What parts of organized bodies are found in the fossil state ? 



3. Are the animals and plants found in the fossil state the same as those . 

 now existing- on the face of the earth ? Are all the varieties of fossils dis. 

 tributed through the divers strata without regard to the age ,f the forma- 

 tions ? 



