PRACTICAL STUDIES IN GEOLOGY. 481 



PRACTICAL STUDIES IN GEOLOGY, i 



CHAS. H. STERNBERG. 



Geology is a world study, and takes the earth as soon as it was cool enough 

 to allow the atmosphere to disgorge its contents on the steaming earth. 



Then began the operation of natural laws, and the causes and effects, as we 

 see them to-day. The rain fell in torrents on the steaming earth, and washed 

 away the solid rocks, and in shape of clay or sand the streams carried it to 

 lower levels and deposited it on the bottom of the sea, as sedimentary rocks. 

 The study of geology is the grandest of the natural sciences, not only because it 

 takes into consideration the largest object with which we have to do, but it in- 

 cludes vast lapses of time, so long in fact that if it does not prove that time is 

 eternal, it shows it least that it is very old. The text-books of the geological 

 student are the solid rocks in which the Creator has written in never fading 

 characters the history of each succeeding period, its life, climate, depth of sea, 

 etc. All the natural sciences bring from their store-houses things new and old 

 to increase its interest. If we go to the sea-shore, and notice the shells lying on 

 the beach which an incoming wave covers with sand, or mud, we see the pro- 

 cess by which fossils are made. The sea may come in and by pressure con- 

 vert the sand, or mud, into solid rock, and the shells will be indefinitely pre- 

 served, and they represent existing species. 



If we notice the accumulations at the mouths of great rivers, like the Missis- 

 sippi, we find, mingled with the sand, or mud, trunks of trees, bones of animals, 

 etc., that have been drifted from the far interior, a thousand miles perhaps. 

 These are mingled with shells and sea-weed from the sea-shore, and represent 

 the life of a continent. The sand and mud may, by pressure, be converted into 

 rock, and the relics be preserved for ages. Petrifaction will take place. This is 

 a slow process: as the contents of the organic cells decay they are carried away 

 by water, which holds silica in solution; this is deposited in the empty cells, 

 making a perfect cast, and so cell after cell is built up of silica. This as I said is 

 a very slow process. In Pliocene time the bones are but partially petrified, 

 while only in the older formations are they completely silicified. Another way 

 nature has of preserving her records is by making casts of shells, leaves, sea- 

 weeds, etc.; a leaf falling in the soft mud is covered up, and a perfect cast made 

 of both sides. In some formations the lime of shells has been entirely carried 

 off, and only casts remain. If we go to Florida we will see the process of rock 

 making. Shells are mingled with the remains of others that the waves have 

 ground to powder, which acts as a cement binding the shells together, strong 

 enough to use for building material. 



If we go into the hills and find in the solid limestone shells, sea-weeds, etc., 



1 Read before the Kansas Academy of Science, November, 1884. 



