MODE XIV. CALCAREOUS GLUTENITE. 533 



grottos appear, from which there issue many 

 streams, that give rise to waterfalls, and thus in- 

 crease the beauty of this striking scene. These 

 caverns are wide at the mouth, but become very 

 narrow towards their further extremity, and are 

 generally very short. This form shows that they 

 owe their existence to external agents, particularly 

 water. A more near examination discovers that 

 the seams of the strata of the different isolated 

 masses correspond to each other ; which renders 

 it probable that all these cones, pyramids, and 

 pillars, have been formerly united; and that the 

 perpendicular rents or fissure^ have given rise to 

 this disunion, which has been afterwards increased 

 by the action of the air, and by the water carrying 

 away the softer or more loosely aggregated parts 

 of the sandstone, and leaving the harder parts in 

 these various forms. A similar appearance of 

 sandstone occurs near Tunis, and, from its striking 

 resemblance to ruins, is described as the remains 

 of a great city, by some travellers who saw it at a 

 distance. In the land of the Namaquas, in 

 southern Africa, and on the banks of the Wolga, 

 there are similar appearances."* This glutenite 

 may, however, be argillaceous. 



* Geognosy, l6l. Soulavie, tome i. gives a print of square cal- 

 careous columns at Ruons, on the river Ardeche. 



