21 



I'jven where* clay jirevails, small layei-s of conglomerate are inserted 

 between it, and jiebbles or other coarser objects are often intermixed witli the 

 sands or clays. We may l)esides add that these sands and clays, toi>-ether with 

 the conglomerates, are always stratified ; the stratiHcation of sands and conglo- 

 merates often jiassing over into those iindulating layers so often seen in them, 

 whilst the clays are perfectly horizontal and exhiliit many smaller and larger 

 strata. 



Though it seeuis very ditiicidt, after all, to give a g(iiid idea and a picture of 

 the diluvial strata, we add a small sketch of the blnft' next to the railway station 

 of Kanagawa (NE from it). It exhibits llie horizontal surface of the upper plain, 

 the upper diluvial sandy clays unconformably overlying the lower diluvial strata 

 of clay, conglomerate and sand, which are not of a very great thickness at that 

 place and imconformably overlie the sedimentary rocks descril ted in the followiii"- 

 chapter. (PI. I fig. 1). 



The practical nse of the lower diluvial deposits is comined mainly to tlio 

 conglomerates, which, if tolerably pure, are frequently dug out for engineering 

 puriMises. Less important is the use of some of the clays for making bricks, or 

 tiles, or even — in small layers of purer quality — for making potteiy in villages 

 whose inhabitants are accustomed to di-aw the materials required lor it from 

 their neighbourhood. 



The admixture of the lower diluvial strata with the tufas belonuiuir to the 

 volcanic rocks of the southern coast near Yokohama etc. is not to l)e omitted, 

 although, within the limits of quaternary rocks, it is by far less extensive than in 

 the tertiary ibrmation. It may be said to be almost fully explained by parts of 

 the tertiary tufaceoiis rocks being destroyed and deposited again by tlie diluvial 

 sea. Although the outbreak of ashes and lapilll continue<l through the present 

 era, and must necessarily have brought some material ofthat Icind lietween the 

 sediment of quaternary origin, yet by far the greater part of that admixture 

 seems to be a secondary de[)Osit and carried over from tertiary tnfaceous strata to 

 the quaternary ones. The volcanic energy, indeed, n)ust have l)egun to abate 

 long before the present era, and most likely about the end of the tertiary and 

 before the very Iwginning of the diluvial ejioch. 



The organic remains of the diluvial formation of Tokio and its environs are 



o 



not very numerous. 



First wo must mention the fragments of wood, half decomposed or even 

 entirely converted into brown coal, whidi frequently occur in sandy or clayisli 

 diluvial Ix-ds, especially near tlieir lower limit. I'rints of knaves are but sparely 

 distributed among those fragments of stems, or of roots, all of wliieli belong to 

 recent species. This is of com^e to be exiwcted sus even most of tlie youngest 

 tertiary fossil plants do not belong to other than surviving species. The leaves 

 occnring most frequently are oak— and asli-leaves, lliose of m.iples, chestmils, 

 wliilst the fragments of wood belong to the sngis or eryptninerias and dbir 

 coniferous plants n<iw lising in Ja[iaii. 



