] 26 PROCEEDINGS OF THE GEOLOGICAL, SOCIETY. [Mar. 23, 



The northern face, which stems the angry surges of the Atlantic, 

 is nearly perpendicular, and affords ample scope for observation. 

 The base is of red sandstone, — dip N.W. by N, Z. 7°. It is covered 

 conformably by the blue fossiliferous shale, and this is overlaid by 

 the tufaceous limestone. 



The summit-ridge is extremely narrow ; it scarcely appears to be 

 20 feet across, and is crowned with an almost impenetrable copse of 

 thorns, growing out of the interstices of the solid limestone rock. It 

 is said that this circumstance induced Columbus to give it the name 

 of Monte Christi. The French afterwards gave it the name of La 

 Grange, from its resemblance at a distance to an enormous barn, by 

 which name it is now more generally known. The miserable vestige 

 of a once flourishing town of above three thousand inhabitants, built 

 at the foot of it, is all that retains the name of Monte Christi. 



The rock- specimens from the different beds of the Grange, when 

 compared with those from the Hills of Samba at Cercado, appear to 

 be as nearly similar as could be expected for the distance they bear 

 from each other. The dip of the beds of the Grange is almost 

 identical with that of the beds of Postrero and Cercado. The blue 

 shale appears to be about 800 feet thick, covered by about 200 feet 

 of limestone in a tabular mass. 



Fig. 7. — Section of the Cliff at the western extremity of the Grange 

 Mountain, showing the interlacing of the shales. 



1 



1. Blue sandy shale, fossiliferous. 



2. Ferruginous calcareous shale, alternating with argillaceous sandy shale ; fossiliferous. 



The cliffs at the western extremity of the Grange display an 

 interesting intercalation of the blue and the yellow shales (see fig. 7) ; 

 the latter is argillo-calcareous, and is, apparently, a large develop- 

 ment of what at Cercado is a thinner bed of 50 feet thick ; it ap- 

 pears, also, to be a modfied form of the calcareous shale so largely 

 developed at Angostura. 



Fossils from the Sandstone plains. — These fossils were collected 

 at Inamagado, Esperanza, Rompino, Cerro Gordo, San Lorenzo, La 

 Salada, and Cana. 



They are found scattered upon the surface of the sandstone plain 

 of the district of Santiago, usually half-buried in silt or coarse sand, 

 sometimes in vegetable mould. 



