FEWKES] 



ANTIQUITIES OP MESA VERDE NATIONAL PARK 



21 



The geological formation of the cave in which Cliff Palace is 

 situated is similar to that at Spruce-tree House, consisting of alter- 

 nating layers of hard and soft sandstone, shale, and even layers of 

 coal. Both canyons and caves appear to have been formed by the 

 same processes. In past ages the elements have eroded and under- 

 mined the soft layers of sandstone or shale to such an extent that 

 great blocks of rock, being left without foundations, have broken 

 away from above, falling down the precipice. Many of these great 

 bowlders remained on the floor of a cave where it was broad enough 

 to retain them. The surface of the roof arching over Cliff Pal- 

 ace cave is per- 

 haps smoother 

 t h a n that of 

 Spruce - tree 

 House. The prog- 

 ress of cave ero- 

 sion was greatly 

 augmented by the 

 floAV of water 

 from the mosa 

 summit d u ring 

 heavy rains, as 

 herein a f t e r 

 described. 



To understand 

 the general plan 

 of Cliff Palace it 

 is necessary to 

 take into consid- 

 eration the metli- 

 od of formation 

 and the configura- 

 tion of the cave 



Fig. 1. — Viev/ down Navalio Canyon. 



floor on which the ruin stands. This cave, as already stated, was 

 formed by erosion or undercutting the softer rock at a lower level 

 than the massive sandstone, leaving huge blocks of stone above 

 (he eroded cavities. Naturally these blocks, being without sup- 

 port, fell, and in falling were broken, the larger fragments remain- 

 ing on the floor practically in the places where they fell, but many 

 of the smaller stones were washed out of the cave entrance, forming a 

 talus extending down the side of the cliff. The floor of the cave was 

 thus strewn Avith stones, large and small, resting on the same general 

 level which is that on which the foundations of the buildings were con- 

 structed. The level of the cave floor was interrupted by the huge 

 blocks of stone forming its outer margin ; and the buildings constructed 

 on these fallen rocks were lofty, even imposing. The talus composed of 



