The Panama conglomerate is probably a shore formation. Its 

 peculiar constituents, the comparatively narrow belt occupied by its 

 deposits, its lens-formed pebbles of quartz, indicate that they were 

 smoothed and polished by sliding back and forth along the shallow 

 waters of an ocean shore, rather than by rolling on its bottom. We 

 may picture in our minds masses of pebbles, fine gravel and sand, 

 accumulating in the devonian age in great beds and irregular heaps 

 upon the northern shore of the vast paleozoic ocean, that for time 

 inconceivable had heaved its billows here. The sand and pebbles 

 washed shoreward by the surf and tide, to be borne back again by 

 the out running streams and refluent waves, would produce just such 

 a collection and arrangement of materials and distribution of masses 

 as make up the Panama conglomerate. It here constituted, probably, 

 the last contribution made by the sea to the growing continent of 

 North America before it became dry land. The great openings that 

 now appear in these rocks, dividing them into blocks, as at Panama 

 and Rock City, are not the result of upheavals, but are solely the 

 quiet work of frost and ice, aided by the weight of the rocks them- 

 selves. A silent process, which is still imperceptibly going on, and 

 which was, during that almost immeasurable period that has elapsed 

 since the devonian age, slowly opened and widened these fissures into 

 passages that have at length come to resemble the streets and avenues 

 of a city, illustrating in a most striking manner the results that time 

 can bring about. Indeed, time is the most important factor in 

 producing all geological changes. The laws that govern matter will 

 not alone account for the phenomena that we find exhibited in the 

 rocks. Pressure and heat would not alone, without time, give us 

 coal. Minute particles of matter held in solution by the sea to be 

 finally deposited at the bottom, could not, without the lapse of ages, 

 be changed to rock hard as flint and become Parian marble bleached 

 as white as the driven snow. Had man existed during all that vast 

 era since the Alps arose from the sea, he would have lived uncon- 

 scious of the movement that has made their peaks to pierce the clouds, 

 so slow has been the process. The time covered by the ordinary 

 history and traditions of his race has been insufficient to show a per- 

 ceptible change. Even now the process of creation is going on. 

 Sweden is rising from the sea. Amsterdam and New York are 

 sinking beneath the waves, and man scarce observes it. Here, upon 

 the shore of the lake, in this very grove, we may learn to what 

 length the process of creation is drawn out. When first formed, 

 the lake was more than fifty feet above its present level, evidenced 

 by the peculiar materials that compose the plains and levels that 

 border its shores. Old beaches extend around it high above its 

 present waters. At first the lake was longer and wider than now. 

 It extended far up the inlet and over the level plain at Hartfield. 



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