CHAPTEll I. 



INTRODUCTION. 



The environs of Tokio, the capital of the Japanese Empire and, at tlio 

 same time, the place in which most of the collections, colleges and schools of 

 Japan are united and in which therefore also t lie university or Daii:;akii has beea 

 foimded, exhibit, geological!}', a much smaller nmuber of rocks and formations 

 than we might wish for. This is the more to be regretted as these environs are 

 part of a vast plain everywhere constructed on the same plan and showing 

 essentially the same formations, so that, in order to reach rocks and strata of a 

 different kind, the student of geology is alwaj-s obliged to make long and rather 

 tiresome trips in a country which, it must be admitted, has but imperfect roads 

 and means of conveyance, and oflers but very few comforts to travellers. More- 

 over, the mountains encircling the large plain of Tokio — the largest in foct of 

 the Japanese Empire, and for that reason most likely selected for the site of the 

 capital — present little variety. In almost every direction we find rocks of a 

 similar character and origin on leaving behind us the formations of the plain — 

 those dihivial plateau-like heights intersected by rivers and rivulets, and more 

 or less broad alluvial valleys, which we are to describe in the first chapters of 

 this paper. Those rocks of the adjacent hills and mountains, forming as 

 it were a vast quadrant, to which the small isolated district of Uraga is to be 

 added, are indeed mostly crystalline sedimentary or schistose rocks, micaschists, 

 calcareous micaschists, chlorite-schists, intermixed with quartzites, crystalline 

 limestones, and cipollines, in a few instances passing over to gneissic rocks, ia 

 other instances (N. and N.W. of Tokio) to quartzitic conglomerates or to 

 limestones containing few kinds of recognizable organic remains — crinoids, 

 belonging to the tesselate ones, orthocerat<i, and fusulinas — , all proving that 

 these rocks are at least of a palaeozoic age. In some parts, as for instance 

 in the Tsukuba-mountains, which, from the northern and northeastern side, 

 project somewliat farther into tlie plain than the rest of the neighboring 

 heights, or in some parts of the Cliichibu district and farther to the west, or in 

 the mountains which northward from Mito verge nearly to the sea-side, we find 

 granites, dioritcs and otlier plutonic rocks of a rather ancient origin; whilst in a 

 few localities, especially in the sontlierii part, along the coast, recent volcanic 

 rocks with their tufas are widely spread. These tufas indeed pas.s gradually into 

 the formations of the plain and especially into the neogcnc tertiary rocks wliich 

 may be said to be the most attractive formation of it. These volcanic rocks have 

 their highest level on the top <if the Fnji-no-yama, lliat well known normal 

 volcanic cone of gigantic dimensions whirli is situated to the W.S.W. of Tokio 



