ETHNOLOGY. 313 



size, tlie rivers and smaller streams bear with tbem only fiue particles 

 of earthy matter, which give rise to alluvial deposits. 



The time which has elapsed since the eud of the Quaternary period 

 bears the name of the present period, and the strata formed during its 

 continuance are called recent de[)osits. They are recent comi)ared with 

 those of the Quaternary period, but not so when estimated by our ordi- 

 nary chronology, since in most cases their formation has i^equired thou- 

 sands of centuries. 



These preliminary ideas enable us to comprehend the essential facts 

 which determine the dates of human paleontology. These dates are 

 established, in the first place by pure geology, in the second by [)aleont- 

 ology, in the third by prehistoric archaeology. 



The geological dates are principally inscribed in the valleys and in 

 the plains, where the great floods of water of the Quaternary period 

 have left deposits in the form of beds, more or less regularly stratified. 

 If these strata have remained undisturbed, they are found superposed 

 according to age. The oldest lie lowest, and are called the lowest levels ; 

 above them lie the mean levels, which are posterior to them, and which 

 in turn are covered by the upper levels, formed during the latter part of 

 the Quaternary period, l^'inally a stratum, more or less thick, of recent 

 formation, consisting of alluvions, peat, &c., almost always covers the 

 Quaternary deposits. 



These different strata are not everywhere found in complete series, 

 and the nature of the elements of which they are composed varies more 

 or less with the locality ; but I cannot now enter into details. I can 

 only give a general idea of the way in which, by the study of the superpo- 

 sition of these beds, that is to say, their stratification, the relative age of 

 the various deposits, recent or Quaternary, is determined. 



In this determination we first apply to geology. Thanks to the data 

 it furnishes, we know the age of the animals whose bones are found in 

 the different strata ; these animals in turn serve to establish the periods, 

 and also the dates of certain formations or partial deposits which do not 

 form a part of a complete and regular stratitication. 



Of the animals living at the commencement of the Quaternary period, 

 some, like the mammoth, only exist now as fossils; these are the extinct 

 animals; others, like the fox, have disappeared from our locality, but still 

 live in other parts of the world; these are migrated animals; and others, 

 like the horse, continue with us^o the present day ; these are called per- 

 sisting animals. 



Extinct animals abounded in the first part of the Quaternary i)eriod. 

 Some of them were immense mammals with terribly powerful limbs, 

 beside which man, naked and feeble, was of little account. Such were 

 the large bear of the caves, {Ur.sus spekcus ;) the great lion, also of the 

 caves, {Fells spelwns ;) the amphibious hippopotamus, {Hip. aniphibius ;) 

 the rhinoceros, with chambered nostrils, {Rh. ticliorMims ;) the ancient ele- 

 phant, (Eleplias antiquus;) and, above all, the giant king of this fauna, the 



