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

o65William Hartshorne had them boredthrough for me in hispits_ north of Freehold. All except the top layer is well exposedin the pits of Win. Conover, near Marlboro'. And theycan be seen in succession, by passing along the valleys of anyof the streams which run through the marl, as the Spottswoodnorth and south branches of South Rivcr_ and in the HopBrook from Taylor's Mill to Marlboro'. 0The following circumstances may produce a little difficulty_at first, in verifying the preceding statements. Whenever theclay, which lies immediately over this bed of marl, has beenworn away, and the marl lies above the bed of neighboringstreams, the rains and surface water penetrate it, to a greateror less depth, and leach off; dissolving out the fossils and leav.ing earth in their places ; changing its color to a rusty red ;and forming numerous flaky crusts, or sometimes strong cakesof impure oxide of iron, in it. • Such n_aris are called dry bankor hill marls. These changes have taken place to a muchgreater extent in some localities than in others. Marls _vhichlie so as not to be subject to the action of surface water, ordralnagc_ arc called wet basle or meadow marls.The characteristicfossils of this bed arc Exogyra eostata,Gryph_ca convcxa, Ostrca faleata, Terebratula sayii and Belemnitesamcricanua A great many others are found, butthey.at6 not so numerous and not so generally present in alllocalities.Lying immediately upon the bed of marl which has justbeen described, and not separated from it by any well markeddivlsion_ is a layer of black clay. It contains scales of micaand grains of sand. In small quantities it cannot easily bedistinguished from the clay of the stratum bclo_rthe marl. Itfrequently contains sulphate of iron (cet_peras); and being oftenmistaken for marl has been used to the injury of the farmer.When composted with quicklime it is tllought to he useful.It _sfrom ten to twenty feet thick, oThe red or fcrruginoussand lies upon the clay just mentioned.It is separated from it by a well marked line of di-"vision. This bed is of {_at thieknesa_ not less than one5NEW JERSEY GEOLOGICAL SURVEY