lit ii distance ofiilHUit 65 miles, and who»e crater, now nearly filled with Uirnii 

 luslioa und ia|iilli, forms a hollow cone not more than alxHit live hundcn'il fc<t 

 below the hij^h and sharp ridge encircling it. The volcanic 'action ha« totally 

 ceased on the high top of the giant-cone, — the liwt eruption, nearly twoctntnrie« 

 ago, having aflfecteil only a side-cone, the Hoyei-san, about half way up fron» 

 the western Icvse — , and we see l>nt slight traces of it in the environs of llakoiK% 

 at a direct distance of aliont 12 miles from the top of the Fnji-niountain, so 

 that it seems to have a-treated to the sea. Indeed it seems to have it« main 

 centre now in the volcano of the island of Oshima, nearly 8SW from Tokio. 

 Not only the lust vigorous eruption- about a century ago, — but also smaller one« 

 seen and described and partly pictured by Kurojiean geologist«, and, as it become« 

 obvious from a great many dates of the seismoscopical offices, a |virt at least of 

 the earthquakes so fretpiently mx-urring at Yokohama and Tokio, |H)int to this 

 fact; whilst nn the other haml, the vuli'iinic ph.u'nuineiion of the district« in the 

 north of Tokio, esi>ecially on the Asaiua-yama, whose last great cniption is 

 recorded to have taken i)laoe 6 years after that of Oshima, is now apparently lera 

 vigorous and not nmch alwve that degree of intensity which is e.xhibited by the 

 hot springs and the sulfurous exhaliitions near Hakone. As for the sedimentary 

 rocks overlying the older crystalline sedinientg, they are, a« far as they are known 

 in this vicinity, all very young, being jxirtly tertiary, partly quaternary. Tlie 

 tertiary rocks, though very thick and developed in dilTerent 8ha[)e. as shale, con- 

 glomerate and sandstone, are not. or not much, older than the tertiär)" rocks 

 which we shall lintl in the plain, and form indeed one and the same system, rich 

 throughout in such s]Hx-ies of mollusca. a.s still survive in the Jajianese Hens. 

 Thi'se rocks lorm sometimi.'s U'ds an<l ii:vsins encircled by the mic^iceoiis SL'histow; 

 rocks, i>iirtly large, as for instance that which e.xti-nds lietween Kigawa and 

 Minano in the district of (/'hichilm, partly snuiUer, as one which has iieen 

 discovere«! in the environs of Sukegawa, in the north of Mito and near the east^TD 

 coiv^t. Other parts of those tertiary strata are spn-ad along the lM)nndarieii 

 between the crystalline system and the quaternary soil of the plain, as for in- 

 stance between ^lito and the moimlains in the nortli of that town, or in the 

 district of Komagori, or westward from Yokohama. The rocks constituting this 

 part of the cciuntiy, which though not |ierfectly contiguous, may lie e.illed u licit 

 encircling the plain, are mostly sandstones, sometimes rather impure and fre- 

 quently jiassir.g into conglomemtes and tufaccfius rocks. In the latter ease they 

 contain sometimes fragment« of jnunice, in the former, they are rich in small 

 and Worn fragments of crystalline rot-ks, representing all the ditVen'nt kinds 

 occurring in the adjacent mountains. The s|iei'ies of fossils found in the sand- 

 stones— imluckily very often mere casts or moulds — are of courso of great im- 

 portance. We shall, therefore, be obliged to recur to them in the following 

 pages. It may suffice here to mention among them Na«yi livesit-ns I'hil., 

 Colmuliella scrijitji L., l^Iya. arenaria L., Cyclina Sinensis Gmel., Mactra veneri- 

 fonnis Desh , Dosinia Ja|)onica Ileeve, whi*?e identity, however, with the true 



