204 
77/e A nicficd II fieoJ<i<ilst. 
Marcb, 1895 
Ihc l}i>;u:<in Hill format inn. rnnn ils cappiiiL;- a hill (if this name three 
mill's soulh i)f M.ila v\'ai). 'riuTe and east ward on the Naxesink Hiyh- 
lunds the altil iide of its siirfaee is about lOd to :5()0 feet jibove the sea, 
declinin<;' toward the east and sonlli, and it has a maximum thickness 
of al)ont lOdfeel. It consists of sand and i:ra\cl. often con tainiiiij' peb- 
bles up to three inches in diameter, and occasionall v liaAinu' I a rji'er cob- 
bles and e\en slab-like masses of sandstone up to t wo feel. Tiie IJeacon 
Hill formation lies on Cretaceous beds which had a nearly ])laiie surface 
at the lime of its deposition: but, the Oi'ctaceous siM'ies made little or no 
contribution toil. Xeit her has it any i)ebbles of uranite. uiieiss, traj), 
jiiibbro, limestone, or Triassic sandstone or shales. Instead, its i;'ravtd 
is the longer enduring- (]uartz. chert, and Hudson River sandstone. In 
Mtmmouth county the <,n'eatei' part of tlu^ Beacon Hill gravel and much 
of the underlying ('relaceous strata iia\e been eroded, ihe genei'al de- 
nudation being 150 to '.TX) feet and the deepest \alleys about KlO feet 
lower. 
Following this 'ireat denudation, the second or Peiisauken formation, 
ranging up to .")() or (id I'eel in thickness, was spread omm' the lowlands 
ami valleys to the high! of I.')!) to •,'()() feel above the .sea. Its pebbles and 
cobbles range in size up to one foot or sometimes two feet in diameter: 
and it contains lioulders. especially northeastward near tiie glacial drift 
bouiulary, whicdi were doubtless borne b,\- Hoating ice, uj) to two, three, 
or even four feet. The gra\'el and Ixiulders comprise granite, gneiss, 
Triassic shale ami sandstone, uahbroand trap, besides much iiuartz. 
chert, etc.; l)ut a \ery charactei-istic fe.iture is the prevail ingly decaj'ed 
condil ion of t he gra nit ic and gneissic material, which underwent this 
change a fier deposit ion. 
MtH'h erosion of Ihe Peiisaulveii deposits had again l)i'ought the drain- 
agi' sysleni to a mature stage of de\'elopmeiit, when the third or .I'ames- 
burg formation was laid down in the valleys under KJO or l.")0 feet above 
Ihe sea. This is a thin mantle of commingled gravel, sand, and loam, 
averaging no more than ten feet thick. freipuMitly inclosing boulders, 
some of which are glacially striated. Subseipnud st ream erosion has 
been slight. 
The fourth or Trenton gra\ d format ion. lying in the ri\cr \alleys be- 
low the comparal i vt'ly high limit of the Jaiiu'sburg lo;im and sand, is 
too vv(dl known to need pai'ticuhu' descrii)t ion. It belongs to the late 
moraiiu'-forming stage of the (ilacial periotl. 
The Beacon Plill, Peiisauken and .laTnesl)urg formationsare attributed 
to marine and est uarim- disposition. with intervening eix'irogenic uplifts 
of the land. It is held by the author as si ill ipu'Sl ional)Ie. whether the 
first is of Miocene or of I>a fayetle a i:e: whet her the second represents the 
l>afa,\ette (}!• the Columbia of the .\tlanlic coastal plain farther south: 
and whether the t bird belongs to t he e.-irliesi oi' to siuiie later stage of the 
general iKirthern glaciation. 
Jlr. T'lMi.v.M. in discussion, called attention to the total lack of marine 
fossils in all these fiu-mations, and to the absence of shore lines marked 
by wave erosion and lieach ridges: hence he would refer all the "Wdlow 
Cravel series to liuvial deposition while the land had a greater altitude 
than now. [From ad\ance sheets of the .Vnnual Report of ihe New ,ler- 
se\ geological survey for IS!):!. recei\;'d. since Ihe Balliniore meeting, 
fiom I'rof. .l-ohn < '. Smock, the state geologist, and from Prof. Salisbury. 
whosi' more full descriptions of these formationsare there presented, it 
seems well demonstrable that the great denudal ion bet wi>en t he Bea- 
con Hill and Pensauken formations should be considered as the same 
wilh that inler\-ening farther south between the Lafayette and Colum- 
bia formations, to be accounted for l)y the great i)reglacial altitude to 
which Ihe land was raised subsequenl to the epoch of deposition of the 
Lafayette beds, finally culminating wilh a high jilateau climate and 
ice accumulation upon the northern half of Ihe continent. — w. t'.] 
