Ridpath's history of the world; being an account of the ethnic origin, primitive estate, early migrations, social conditions and present promise of the principal families of men .. . ater and still greater depths, until at the presentday it is a common circumstance, both inEurope and America, to find the watersurface of running streams as much asa hundred feet or more below the levelformerly occupied by the river. Almostevery considerable stream presents oneither side a secondary terrace ofdrift which, at a former age, markedthe level of the bed. With the reces-sion of the waters to the presen
Ridpath's history of the world; being an account of the ethnic origin, primitive estate, early migrations, social conditions and present promise of the principal families of men .. . ater and still greater depths, until at the presentday it is a common circumstance, both inEurope and America, to find the watersurface of running streams as much asa hundred feet or more below the levelformerly occupied by the river. Almostevery considerable stream presents oneither side a secondary terrace ofdrift which, at a former age, markedthe level of the bed. With the reces-sion of the waters to the presentchannels, the caverns formed in theold diluvial banks, especially thosein calcareous regions, have been leftdry. The mouths of such alluvialgrottoes open on the hillsides, facingthe rivers, and it was into thesecaverns that the animals, includingprimeval man, made their way as placesof natural resort in the earlier ages ofthe postglacial epoch. In the bottoms of nearly all of thecaverns are found a certain residual ofloam, or cave-earth, swept Date of remains in as sediment by the de- indicated fromparting waters; and over geo oglcathis loam there is usually a solid layer of. EXAMPLE OF STALAGM1TIC FORMATION. stalagmite. Whatever organic remainswere left in the caverns in the age ofthe deposit were, as a rule, mixed with theloam, and afterwards covered and, as wf. 92 GREAT RACES OF MANKIND. might say, hermetically sealed, with stal-agmitic material. It is easy to perceivethat a study of the rate of diminutionand sinking away of the rivers from theirformer elevation into their present bedswould furnish a measurement of timefor estimating the date of the depositof the human relics referred to. In sofar, therefore, as geology is able to de-termine the time at which the alluvialcaverns were formed and at which thereceding waters left them subject to hab-itation, she is able to suggest an ap-proximate date for the appearance ofman-life on the earth. The facts here referred to, whic
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Keywords: ., bookcentury1800, bookdecade1890, booksub, booksubjectworldhistory
