ARCHITECTURAL FORMS IN NATURE. 



65 



contains one of these fractures (due to weathering) and is not thick, 

 some crevice is sure to open a path to the enemy, which is soon 

 widened to a highway for the frost and rain, and a cascade in 

 shower-time pours down, picking up sand as it goes to help in the 

 attack. The weathering becomes more rapid, the arch opens up, and 

 in time a natural bridge (Fig. 2) spans the air where once there 

 was but solid stone. The process continuing, the bridge will dis- 

 appear, a vacancy will take its place, and far off in the river bottom, 

 or still farther in the sea, will rest the disintegrated material that 

 once made part of the continuous cliff. Where the cliff is too thick 

 to be perforated (Fig. 3), the arch breaks back into a deep cavern 

 whose roof falls and falls till the blue sky takes its place. Thus has 

 a natural bridge, like a flower, its birth, its growth, perfection, and 

 decay. Wind erosion also plays a part, but the chief work is due to 

 water. 



Besides bridges there are numberless other forms. Who has not 

 seen Castle or Pulpit Rocks, or Devil's Slides, or Palisades, etc.? 



Fig. 3. — Middle Stage of a Bridge or Arch. 



But it is in the West, perhaps, that the most remarkable rain carv- 

 ings and wind carvings occur, and especially in that part called the 

 Southwest, that " land as old as time is old," that strange, weird land 

 of red rocks, of tall, long cliff lines like mountain ranges split asunder 

 to span the desert in their nakedness; that land of labyrinthine 

 canons, where the bloom of morning lingers to kiss the gloom of 



VOL. LIV. — 6 



