81 



of the sea. This movement of the entire mass of land forming the Japanese 

 aruliipehigo, has, to a certainty, not gone on quite regulai'ly and must have heen 

 at times interrupted; but, on the whole, it has continued from tlie last period 

 of tlie tertiary age to the present day. The interval between the pliocene layers 

 t.nd the diluvial strata, causing that line of unconformubility often mentioned, 

 may have been filled up by an extent of land greater than at present; and the 

 occurrence of two of the paliKarctic species of elephants seems to point to the 

 same fact. But Soon after the beginning of the diluvial era another submersion 

 must have taken place to wliich another elevation succeeded. And this elevation 

 li;is doubtlessly continued up to the present time. 



This seems to be proved, if not with certainty, yet with some probability, 

 by the Omori shell-mound. A mound of such a size is likely to have been 

 heaped next to the sea; and I think the discoverer of this mound is perfectly right 

 in laying some stress upon this matter. 



On the other hand, it seems scarcely possible to make any calculations 

 concerning the amount of the increase of land, or the rapidity with v.hich the 

 soil of Japan is elevated above the level of the sea. Much greater precautions 

 must be taken, in this respjct, than has generally been the case. If we should, 

 for instance, compare the result of the soundings in the bay of Tokio made at 

 different periods, we might perhaps, at a short distance from the shore, ]ierceive a 

 comparatively great diminution of the depth of tlie bay, and yet the real amount 

 of the elevation might be trifling. For a large mass of detritus is daily brought 

 into the sea by the rivers, by the sea itself, by men; and this mass i.s distiibuted 

 mostly along the coast. We are not allowed, therefore, to draw any conclusions 

 ccncerning a rising of the entire mass of land from soundings made next to the 

 shore, especially in the harbours, and above all iu the harbour of Tokio. Just 

 as untenable are the results derived from the increase of land in the precincts of 

 the town itself. Swamps extending along the coast may have been made artifi- 

 cially accessible to men, and therefore they arc said now to be land, whilst on 

 the old maps and in the old traditions they are said to belong to the sea. To 

 this Increase of land, which must be declared to be strictly local, the stagnations 

 produced by weirs — above which always a largo bulk of detritus is retained and 

 accumulated — add of course a great deal, and this has been evidently the case In 

 some parts of Tokio. 



I am far, therefore, from sharing the views contained on this subject in Dr. 

 Naumanns paper on the Tokio plain. Especially do I think that his estimate 

 of years is incorrect. The very short time assigned for the formation of the 

 plain of Tokio, viz. 45000 yeai-s— given, it is true, as a minimum— seems to bo 

 quite inconsistent with the amount of time which we really must assume for our 

 geological periods. 



Still le.ss tenable, of course, is the view that wdthin historical time the 

 Tokio plain lias ever been covered by tlic sea. This is not only the case with 

 the liigher jmrta of the plain formed by diluvial strata, but also for tho lower 



