NJDEP - NJGS - First Annual Report of the Geological Survey of the ...

increasing upou the surface. It is in this form that extensivedeposits of marl occur in tdmost every part of this county.NVherever such dcposi*tsh.ave been examined, they are usuallyfound to rest upon a bed of clay, sand or grave!, and are succeededby muck or peat. At or near the junction of the'peatand marl, a layer of living testacea generally qecurs_,mingled.with the peat. From twenty-five to thi.rty inches below this,the livit_g animals disappear, their places being occupied by.their remains.i n a decomposed state. The shells most frequentlyfound in these deposits are the Limuea _jugularis, Valratatriearlnata , Cyclas .similis,.Planorbis biearifiata, aadlsomcother species.Spr!ngs holding a large quantity of lirae in Solution, somet_mesdeposit it on the surface in the form of a. loose porous.• mass. It often happens that twi_ and leaves are enveloped.in these deposits_ and their impressions thus p'reservecl in a.most beautiful and perfect manner. Such deposits are cal!edcalcareous sinter, "calcarcous tufa or traver_in. _xtens.ive de-:posits of calcareous sintcr and shell marl are found, in every• part of'this county, r£he"most important localities are i_ the'limestone districts. A largo deposit of shell marl is foundalong, the course of Chambers' Mill Brook, in Mon_gue(.Township on the farm of 'Isaac Bonnell, Esq: : This deposit,covers an area of i_romseventy-five to one hundred acres. Itis situated in a low meadow or marshy land, surrounded by;limestone hills ; and this meadow has, at bus time, doubtless,been covered by a shallow lake or pond. Near the centre ofthe depesit_ an examination was made to the deptl_ of eighteenfeet, giving the following section : . .Peat and muck 8 feet.Marl and. peat containing living testacea, 4 feet:: :Mp.rl/,very'fine, made up of decomposed shells, 11 feet:The.instrument not' being of sufficient length, the wholethickness of the depomt was not ascertaaned. In other placeswhere examinations were mac_e,thepeat was forbad t9 be from., t . . : .five to tea feet in thickness; and from "six to ton feet from48NEW JERSEY GEOLOGICAL SURVEY