observed on Rucks on the Shores of Greece. 345 



those above described. The circumstances which distinguish 

 this phenomenon from the analogous one upon the present 

 shores, are, 1*^, the existence of a cuticle of lichen uniformly 

 covering the rock, which announces that the action that pro* 

 duced the erosion has ceased ; 9.dly, the obtuse form of the 

 ridges and of the borders of the cavities ; 3JZ//, the much 

 greater dimensions of the normal grooves. 



These groves, which on the border of the sea scarcely exceed 

 a few millimeti-es in depth, present in some localities in the in- 

 terior, principally upon the low valleys which border in the 

 sea, a breadth of from 1 to 2 decimeters, with a corresponding 

 depth. 



These grooves, in their course, often meet with cylindrical 

 irregular holes, which belong constantly to the limestones in the 

 same locality ; then they penetrate the limestone, and are de- 

 lineated at its surface. Thus those cavities had already been 

 produced when the action which gave rise to the grooves still 

 existed. The great dimensions of the ancient grooves would 

 be explained by the long continued action, and perhaps by dif- 

 ferent atmospherical circumstances ; the elevation and extent of 

 the surfaces upon which we observe them, by the movements of 

 the land and of the tide, as powerful then upon the Mediterra- 

 nean shores as upon those of the present ocean. In every place 

 where these normal grooves exist, you will be sure to find be- 

 neath, and in general at a small distance, certain signs of the 

 existence of ancient shores. These are either the superior limits 

 of the tertiary district resting upon the ancient district, or 

 lines of pebbles and rocks in situ perforated by borino- mol- 

 lusca; or, finally, surfaces of decayed limestones perforated 

 with numerous tortuous cavities with rounded surfaces. I be- 

 lieve that it may be established with certainty, that there is 

 an analogy between these surfaces, covered with grooves of 

 the greater declivity, and the white zone of the shore. I would 

 now establish the same analogy between the surfaces with tor- 

 tuous cavities of which I have just spoken, and the decayed 

 zone, in some manner beaten by the tide. Both sorts present 

 the same kinds of destruction, only the rocks of the interior 

 have lost their asperities; the cavities arc not only rounded 



JULY SEI'TKMBER 1831. Z 



