BRANNER: THE STONE REEFS OF BRAZIL. 125 
ancient indentations of this coast have been obliterated by time and 
the sea. 
Comparative effects ‘of elevation and depression. — The relations of 
the reefs to the shores and to the coast topography makes it necessary 
to deal with the topographic forms of the reefs and to understand by 
what processes and in what order they originated. 
The general effects of elevation on any coast will be considered first, 
and afterwards the effects of depression, and then by comparing the lit- 
toral forms thus produced with those of the Brazilian coast the writer 
will try to determine by which of these movements its present features 
have been produced. 
Effects of elevation. — If any coast were considerably and abruptly 
elevated the old beach-line would form a terrace, the old undereut shores 
would be marked by an incised line produced by the former work of the 
waves, the coral reefs of the region would be exposed, the polyps killed, 
and the remains of marine animals, especially the Mollusca, would be left 
strewn across the newly raised land. The streams would have their cur- 
rents increased about their former mouths and would immediately begin 
to cut into their rock bottoms and to make deep, steep-sided channels. 
If there were partly enclosed bays or lakes along the former shores, their 
outlets would cut deep channels back into the lakes and they would be 
drained at once. Inasmuch as the irregularities of the land, on account 
of subaerial erosion, are more marked than those of the sea-bottom, a 
depression would, as a rule, yield а more indented coast-line, while an 
elevation would yield a coast with but few harbors. 
An elevation of three or four metres on this Brazilian coast would pro- 
duce a peculiar effect upon the stone reefs; the waves would undermine 
the reefs, for as has elsewhere been shown, they are hardened only to 
this depth, and they would break into angular blocks and strew the 
newly made beach with their remains. 
Effects of depression. — If a considerable depression took place on a 
sea coast, the valleys near the coast would be flooded and would become 
bays, narrow estuaries, or fjords, according to the shapes of the valleys. 
In general, the coast-line would have the dentritic form suggested by 
the coast of Maine more or less marked, according to the relief of the 
region before the depression took place. 
This is so universally true that Dr. James Geikie in his recent work 
upon “Earth Sculpture” states (р. 328) that, “All highly indented 
Coast lines are evidence that the land is sinking or has recently sunk.” 
Lord Avebury, in his “Scenery of England,” observes (p. 125) that, 
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