b. 
h. 
32 
then worn down after the volcanoes have become 
extinct. 
Six models, in pairs, showing the interaction of 
neighboring streams in wearing down a region. 
Note adjustment of drainage to structure of rocks. 
Three models showing formation of alluvial plain, 
the later conversion into a terraced valley and final 
removal of all loose material in the valley. 
Exhibited by the Geological Departmont of Har- 
vard University, through Prof. W. M. Davis, Chair- 
man. 
4. Maps. 
Geological map of State of Alabama, showing re- 
lation of lands worn down in Cretaceous times to 
the surrounding unconformable Cretaceous sedi- 
ments. 
Map of the alluvial plain of the Mississippi show- 
ing many features typical of rivers in their old age. 
Note position of stream in the flood plain. , 
Relief map of New Jersey showing the physical 
features. 
Geological map of New Jersey to be compared 
with above to note relation of the topography upon 
the character of the rocks. 
Map of New Jersey showing water basins, illus- 
trating the complete division of a land into river 
basins. 
Map of the United States colored to show the re- 
lief and physical features. 
Topographic map of Now York and vicinity to 
show the relation of the position of the city to the 
physical features and history. 
Topographic map of Rhode Island showing effects 
of glaciation upon drainage and the recent changes 
in position of land in reference to ocean. 
