186 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
beaches of all tropical seas solidified by lime deposits. It is unnecessary 
to say that such is not the case. So far as mere temperature goes, the 
surface waters along the northeast coast of Brazil are probably neither 
warmer nor colder than those along the shores in many other places 
within the tropics. And yet the northeast coast of Brazil is almost the 
only one along which the beaches have been extensively solidified. 
In view of the exceptional character and extent of the stone reefs of 
Brazil, it must be admitted that the theory of the deposition in them of 
lime carbonate, due solely to the increase of the temperature of the water, 
is not satisfactory. 
III. Lime carbonate from the land. — Waters flowing from a land sur- 
face of limestone would necessarily be charged with lime. If such 
streams entered the sea without other dilution, there would be a ten- 
dency for them to deposit their lime contents immediately upon entering 
the sea. This precipitation is due to the saturated condition of the two 
waters. The Rhone, emptying its strong lime waters into the Mediter- 
ranean Sea, deposits lime with its silts, and the beaches about its mouth 
are in many places consolidated. Lyell remarks, in speaking of this mat- 
ter: * If the number of mineral springs charged with carbonate of lime 
which fall into the Rhone and its feeders in different parts of France be 
considered, we shall feel no surprise at the lapidification of the newly 
deposited sediment in this delta.” * 
The rocks of western Palestine and of southern Asia Minor are made 
up almost entirely of limestone, so that the streams flowing from that 
land surface enter the already dense waters of the Mediterranean Sea 
heavily charged with lime, and the precipitation of that lime on the 
shores bas made the reefs and consolidated beaches described by Beau- 
fort,? Botta, Lartet,* and Hull. 
Inasmuch as the stone reefs of the Levant seem to be about the only 
extensive ones in the world comparable with those of northeast Brazil, it 
seems best to give here some account of them and of the conditions un- 
der which they appear to have been formed, in the hope of getting light 
upon the Brazilian stone reefs. 
1 Charles Lyell, Principles of geology, ed. 11, L, р. 426. New York, 1889. 
2 Е. Beaufort. Karamania, p. 10, 18, 174, 178, 207, 211, 212, 258, 289. On lime 
in the streams, p. 130, 185-136, 141, 191, ed. 2. London, 1818. 
3 Observations sur le Liban, etc. Mem. Soc. Géol., France, ed. 1, р. 135-160. 
4 L. Lartet. Exploration géologique de la Mer Morte. Paris, 1877. 
5 E. Hull. The survey of Western Palestine. Physical geology and geography. 
London, 1886. 
