6 VIEW OF THE FAUNA OF BRAZIL 



found in sufficient quantity to become an article of industry 

 and export to the neighbouring population. The origin of 

 this salt was for a long time obscure to me ; but at length 

 numerous observations and experiments have convinced me 

 that it is neither formed in the soil where it lies, nor contain- 

 ed in the limestone in which the caves occur, but that it owes 

 its origin to the bed of mould which lies above the caves. — 

 The rain water that filters through this mould becomes charg- 

 ed with decomposed vegetable particles, and by contact with 

 the limestone in its passage through the fissures, the salt is 

 produced. 



Most frequently this bed of soil is covered with a coating of 

 stalagmite. In my foi-mer communication, describing the cave 

 of Maquine, I have drawn attention to the difference in the 

 manner and period of formation of this stalagmitic crust, and of 

 those columnar and leaf-shaped productions, which, either as 

 stalactites, hang from the wall or clothe the roof in a thousand 

 fantastic and indescribably beautiful forms, or, as stalagmites, 

 rise like enormous pillars or cones from the floor. By far the 

 greatest quantity of this stalactitic mass belongs to ages an- 

 tecedent to the introduction of the soil, which is seen resting 

 on it as a base, just as the soil outside rests on the base of 

 the older rocks. A much smaller portion has formed since, 

 and indeed it continues daily to increase, even under the eye 

 of the observer. On the other hand, the stalagmitic coating 

 which covers the surface of the soil, must have been a later 

 production, to which many causes have contributed ; these 

 causes it is important to distinguish, in order that we maybe 

 enabled to decide upon the age of the organic remains found 

 under the stalagmite. In the communication already referred 

 to, I have proved that the formation of the columnar and leaf- 

 shaped stalactite is effected by a very slow process. If the 

 dripping of the water proceeds too rapidly, its dissipating pow- 

 er prevents its setting, and the stalagmitic mass below is hol- 

 lowed out, instead of being increased. The calcareous water 

 which runs down the sides of the stalagmitic blocks, collects 

 in the first hollow it finds near their base. There, and on its 

 passage thither, it gradually deposits its lime, and thus there 

 is gradually spread round the stalagmite mass, and in the de- 

 pressions nearest to it, a calcareous coat, which the water 

 continually enlarges, until by the filling up of the first hollow 

 it is compelled to flow onward to the next, and so on. The 

 splash of each drop that falls upon the stalagmitic mass also 

 contributes to form a similar incrustation around it ; as may 

 easily be seen fi-om the innumerable small inequalities of the 

 surface, which, with the faces of their crystals, often give an 



