120 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
had a false dip on the steep front varying from 34° to 37°. An un- 
usually steep beach up and down which waves were running at the mouth 
of Rio Sapucahy had a slope of 11°. 
Liais states, however, that these reef beds are sometimes vertical, 
This is true, but in no case has the writer seen a reef rock in place in a 
vertical position. The hard reef rocks rest upon soft sands; it fre- 
quently happens that the reef is undermined by currents, and huge 
blocks of stone falling in the soft sands are left tipped about in various 
positions and even standing on end. 
3. Reef rocks above high tide. — Whether rock above high tide can 
be accepted as evidence of elevation depends on how the rock was 
formed. M. Liais speaks of the reef rock as having been formed beneath 
the sea. If that were the case, the reasoning might pass, but it is doubt- 
ful, to say the least. The toppling over of a large mass in the manner 
just referred to sometimes lifts one end out of the water and beyond the 
reach of high tide. Besides such cases there are instances of the harden- 
ing of beach sands beyond the reach of the tides. This hardening may 
be caused either by spray being blown by the wind several metres 
higher than the tides rise, or it may be produced by rain water dissolving 
the lime from the upper layers of sand and depositing it again lower 
down. There are many excellent illustrations of this hardening of sands 
far above tide on the island of Fernando de Noronha” and at other places 
in the world, though the writer does not remember to have seen any on 
the Brazilian mainland. 
The case of the recession of the sea cited by Capanema occurs in the 
State of Ceara. He says of it: “In Ceará the elevation has been соп- 
siderable near Aquiraz in a place where the sea has receded ten fathoms 
in thirty years, and to this the inhabitants cannot apply their favorite 
explanation — the accumulation of gand — for the poles have not been 
covered."? The italics are mine. He does not state whether or not 
the land uncovered is hard rock or soft sands and clays, and in order 
to judge of the meaning of such phenomena it would be necessary to 
1 L’Espace Céleste, р. 545, 548. 
2 J. C. Branner. Geology of Fernando de Noronha. Amer. Journ, Sci., 1889, 
XXXVL, р. 160-161. 
J.C. Branner. The «eolian sandstones of Fernando de Noronha. Amer. Journ. 
Sci., 1890, XXXIX., p. 247-257. 
H. B. Woodward. The Geology of England and Wales, ed.2, 1887, p.546-7, 550-1, 
Т. McK. Hughes. Ancient beach and boulders near Braunton and Croyde, 
Quar. Journ. Geol. Soc., 1887, XLIIL, р. 657-670. 
з Ор. cit., p. cxxxvil. 
