HOW TO MAKE A GEOLOGICAL SECTION. 
395 
DESCKIPTION OF THE PLATE. 
Fig. 1. Topographical map to assist in a proposed geological section of 
the country represented. 
2. Section illustrating the geological structure of the country in the 
map : — 
References. 1. Shales broken by an anticlinal axis. 2. 
Sandstone. 3. Shales. 4. Sand. 5. Lime- 
stone. 6. Gravel. 
,, 3. Vertical section of a coal sinking. 
,, 4. Section exhibiting the sequence of a large number of rocks to a 
great thickness by surface observations. 
,, 5. Section corresponding to fig. 4, but having the scale for heights 
double that for distances. 
„ 6. Ideal section through England : — 
References.., 1. , Silurian. 2. Devonian. .^ 3. Carboni- 
ferous and Permian. 4. Triassic. 5. Lias and 
Oolitic. 6. Lower Cretaceous. 7. Chalk. 
8. Tertiary (Crag). 
,, 7. Section illustrating the .proposed origin of certain kinds of coral 
islands. 
„ 8. Section illustrating the results of intersection of a mineral vein 
by two dykes or elvans. 
„ 9. . Section illustrating the origin of certain springs. 
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