CHAPTER II 



THE ALLUVIAL DEPOSITS. 



It might sei.'iii perhips that the alluvial deposits are companitively of little 

 consequence aivl, therefore, less interesting than the rest of the stratified fonna- 

 tions. Inconsistant as tliis mode of viewing things is witli true science, it turns 

 out to he perfectly erroneous whenever we enter more deei)ly into the subject. 

 Not only is the agricultural importance of the alluvial deposits of the river-val- 

 leys and of the deep plains along the sea-side very great, hut also a uiiimtc 

 investigation of all these deposits is of utmost conseiyience theoretically, for any 

 studies of prehistoric remains. 



I need not dwell upon tliis point, as another ^lemoir of the Daigaku, 'The 

 Shell Mounds of Omori' ( hy Edward S. Blorse (Vol. I, part 1 of the memoirs) 

 shows sufBciently the great importance which these researches liave especially 

 for the district whose geology we are treating here. This importance calls 

 for the greatest precaution with reference to those shell-mounds, the more so 

 as there are a great many difficulties to he overcome. It would lie prepostcrou.s 

 to call every larger aciuuiulatioii of shells a shell-inoinid ; many of them are 

 produced Ly nature and not hy nieu ; other are aecuninl.ited hy men in more 

 recent (historic! times. But a great many of these de[ic>sits are indeed the 

 product.s of humui action in a remoter jieriod. The characters belonging to 

 such artificial shell mounds are, of course, easily determined — those mounds are 

 never overlaid hy any hut recent alluvial de|)osits — they are accumulated and not 

 arransred in iave:s or strata — and moreover thcv are, if not alwavs, yet almost 

 always intermixcil with products of human art and industry, with waste of 

 cookery, bones of animals &c. Tlie nature of tlie |iniduets of art as well as flie 

 character of the human bones occasionally loan 1 williin the mounds gives 

 always the best intimations of the age to which they lielong. 



All these objects having bi'eii carefully taken into consideration, we may 

 indeed safely accept the result of the above (|Uoted author concerning the 

 prehistoric char.ieter of the uiouud of Oniori— and also that of Onomnra, 

 province of llig", mentioned i)y Morse in the chapter about the platycnemic 

 tibia;—, tho'igh we may omit a further iliscnssion about the e.vict era of it« 

 construction. 



Of course in a comitry where people arc e.iting daily a very large ipiantity 

 of shell-fish, wc iiave shell-heajw or deposits of any date up to the present day, 

 and as tho.se lieaps arc almost always accumulated m-xt to the human dwellings, 

 they may be very ea.sily mi.staken for shell-mounds by any one who is not well 

 versed in anthropological researches. Wherever such accuuinlatioiiB are found 



