( 340 ) 



Geology. — " /)i'('/) fxui/di'r-c/d'/ /x'ds i>l' (I Idlli'i' (f/i/c/ttl jx'rtcd til 

 Surtli-lloll'iiid" . Vi\ Prof. Eki. J)i hois. 



(CloiimuiiiicalL'd liy I'lof'. Mahti.n in llii' merliiig oC May ;>(), l".)o:->). 



Ill tli(> (lillies ncai" (*as|i-i('iiiii, horiiiüs li.-nc Ihhmi done lal<»Iv. n 

 proxiiu'ial liiiialic asvliiiii Ikmiiu' plaiiiicd on llic s|»ol. Willi the kind 

 permission of Mi{. .1. Scnoi/rKN, cliict-cnuiiHM'r ol' the "l*i-o\iiicial(' 

 Wak'i'slaat" in Xortli-llolland, 1 was allowc^l to inal<(' sonic livdro- 

 lo^^ical obserx'alions and to inspect llic spcciinciis of' the sediments 

 met with in the Uorinizs. 



When exaininini:' them a remarkalde peciiliarit v came to liuht, 

 A\lii(di I snltseipientl V learned to ha\(' heen round al^o in a lormei' 

 hoi-iii'>' at Uitgeest. 



While, iiamel\ . in the dimes at ('astrienm, down to the lowest depth 

 of the borings, no geological facts were ol)sei"\ed not known to me 

 from elsewhere, in two lioring-lioles, at a distance of al>oiit half 

 a kilometer from each other, fr(tiii north to south, at a (le|»th of 

 32.5 '. A. P., a \ erv tough clav was fmiiid w hieh possesses 

 all the (pialities of Ixmlder-clav. Immediately on it rests a bed, 

 about 12 M. tlii(d;, of coarse-grained sand and gravel, which, near 

 to its basis, together with Ivhinish pebbles, contains also Scandina\ian 

 ones. \ er\ probalde se\eral circumstances point in that 



direction — many, at least of the latter, had been imbedded in 

 tlie clay. 



As alread\ said, the tday was \ cry longli, mixed lio\\e\er with 

 very angnlar. liner and coarser gi-it. Washed, it proves to consist 

 for a large proportion of real (day (liydr(ms alnminons silicate). 

 Dried it is hard as bri(d\s. In short it is a real, glacial boiilder-clay. 

 The colonr is bliiish-grey ; yellow or reddish (day could indeed not 

 be expected at such a depth. 



The pebbles from the gravebbed, and partly no donbt from the 

 clay, are remarkable for their petiographical character. 



Besides (piartzite of different colours and fine-grained sandstone 

 largely intermixed with mica, while (piart/,. lydile. Hint, there are 

 granite and some other stones of eriij>live rock species; amongst 

 others also aliu'iite, altogether 30 pebbles, all of them e\idently of 

 Scandinavian origin, but 1 also pi(d<(xl n|) from th(> gravel, overlying 

 the clay-l)e(l, (part of it apparently had got washed ont from the 

 (day-bed by the boi'ing process) some thirty pebbles of Silurian 

 limestone, mostly beyrichian-limestone, of the same kind as those, 



