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Crellic Pontain Sectory 09
Page 04
No one can doubt but that this deposit of cave earth itself requires a prolonged time for its accumulation.<8> But this period, however prolonged, at length comes to an end. From some cause, both animals and man again abandoned the cave. Another vast cycle of years rolls away--a time expressed in thousands of years--during which nature again spread over the entombed remains a layer of stalagmite, in some places equal in thickness to the first formation. Above this layer we come to a bed of mold containing remains of the later Stone Age, of the Bronze, and even of the Iron Age. Below the first layer of stalagmite--the completed biography of Paleolithic times; above, the unfinished book of the present. Such are the eloquent results obtained by the thorough exploration of one cave. The results of all the other explorations, in a general way, confirm these. Mr. Dawkins explored a group of caverns in Derbyshire, England. These caverns and fissures are situated in what is known as Cresswell Crags, the precipitous sides of a ravine through which flows a stream of water dividing the counties of Derby and Nottingham.
This period produced the great beds of coal we use to-day. But the vegetation of the coal period would present strange features to our eyes. The vegetation commenced with the lowest orders of flowerless plants, such as sea-weeds; but, before it was brought to a close, there was a wonderful variety and richness of plants of the flowerless or Cryptogamic division. In some of the warmest portions of the globe, we have to-day tree-ferns growing four or five feet high. During the closing part of the Paleozoic time, there were growing all over the temperate zone great tree-ferns thirty feet or so in height. Some varieties of rushes in our marshes, a foot or two in height, had representatives in the marshes of the coal period standing thirty feet high, and having woody trunks.<7> Near the close of the Paleozoic time, vegetation assumed a higher form of life. Flowering plants are represented. Pines were growing in the coal measures.
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