DELVING INTO A PREHISTORIC RECORD 
paleobotany on a scientific basis. He lived in Paris dur¬ 
ing the first half of the nineteenth century. In the middle 
years of that century, the study of fossil plants developed 
in England and in Germany, and became an important 
field of investigation there, as well as in France and in 
North America, gradually spreading to other countries, 
and enlisting the interest of more institutions of learning, 
until it became a well-established branch of botanical and 
geological research. 
The fossils from which paleobotanists learn about the 
plant forms of the geologic ages are found in various 
kinds of rock formations in all parts of the world. Slate, 
shale, and sandstone contain many plant deposits or 
fossils. These three kinds of rock are sedimentary for¬ 
mations. They were formed from material washed down 
from hills and mountains, and deposited in either fresh 
or salt water during some great inundation. These inun¬ 
dations were usually caused in geologic times by the 
movement of the earth’s crust, which caused the land to 
subside and be covered by the sea; or they were the 
products of slow, everyday processes of erosion by rain 
and water action. 
Slowly, changes in the earth’s crust were being carried 
on through all times. Eventually, there would be an 
upward movement, and the land which had been under 
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