The Natural History of Chautauqua 



and allows the huge fragments of conglomerate to assume various at- 

 titudes. 



The Panama Rocks are located in a ridge that lies in a north-and- 

 south axis, and which rises just west of the Little Broken-Straw Creek. 

 This ridge is cut through by a branch of the creek which is cutting 

 back into the highlands to the northwest. The Panama rock is made 

 up from top to bottom of alternating layers of sandstone and conglom- 

 erate, blending with one another as the proportions of sand and pebbles 

 varied intermittently during the deposition of the materials. Fre- 

 quently a layer of pebbles consisting of only one course may be seen 

 running horizontally for rods along the face of the cliff. The pebbles 

 lie flat, and the sandstone having weathered from above and below 

 them, their projecting edges jut out and glisten in the sunlight like a 

 string of beads suspended in front of the sandstone. In some cases two 

 or three courses of pebbles in immediate contact have been deposited 

 between purely sandy masses, a foot or more in thickness. 



The rock is a massive conglomerate composed of quartz pebbles and 

 sand, with a high percentage of sand to pebbles. The pebbles are in- 

 variably lens-shaped, and are mostly under an inch in diameter. They 

 are generally of very pure white quartz, sometimes pink. Occasionally 

 one finds red or slate-colored jasper. The whole aspect of the rock 

 suggests the story of a gravel heap along an ancient shore line reached 

 by occasional storms, the waves of which have reached into the beach, 

 the " back tow " bringing out and distributing systematically the pebbles 

 over a smooth and sandy floor. 



This remarkable conglomerate rests upon a series of richly fossiliferous 

 blue and bluish-green shales. Through the disintegration of these soft 

 shales under the conglomerate the latter has been broken and fissured. 

 Glacial action has perhaps assisted in this work. These cracks are two 

 to ten feet wide, and occur about every forty feet, breaking the bed 

 into blocks seventy to eighty feet long. The layer is about seventy 

 feet thick. 



All of the " rock cities " of southern New York and northwestern 

 Pennsylvania have been formed in this way. Many of them are situ- 

 ated on the highest hilltops, Panama Rocks are 1671 feet above sea- 

 level, but they are always composed of rocks in situ. They have 

 neither been brought from a distance, nor have they been fhrown up 

 to their present position, as popularly imagined, by " convulsions of 

 nature." Their formation has been as slow and as quiet as the opera- 

 tions of frost and water amid which we live. The rocks are merely 

 the last remnants of thick and extensive deposits of coarse sandstone 

 that once covered this portion of the country, and are now everywhere 

 else removed. 



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