STATE OF DELAWARE

DELAWARE GEOLOGICAL SURVEY

REPORT OF INVESTIGATIONS NO.6

SOME OBSERVATIONS ON THE SEDIMENTS

OF THE DELAWARE RIVER

SOUTH OF WILMINGTON

By

Robert R. Jordon

and

Johon J. Groot

Newark, De lawa reFebruary, 196 2

Public Access CopyDO NOT REMOVEfro m room 208 .

SOME OBSERVATIONS ON THE SEDIMENTSOF THE DELAWARE .RIVER

SOUTH OF WILMINGTON

By

Robert R. lordanGeologist, Delaware Geological Survey

and

lohan I. GrootState Geologist

February, 1962

CONTENTS

P...

Introduction. • • • • • • ••

Abstract ••• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • '.e ••••••••

................................• .1

.1

Description of samples .........•..•.................... • •••••••••• 1

Megascopic descriptions • . .....•................................... 1

Microscopic descriptions ...........................................• 1

. 4Mechanical analyses ••

Heavy mineral analyses

.......... ............... , .

. . .... ........ ...... . . • 4

Clay mineralogy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Plant microfossils • ................. ... .. . ............... .6

Discussion ' 6

References. . . . . . . . . . . . . . . . . . . . . . . . . . 12

ILLUSTRATIONS

Figure 1. Location of boring studied in this report • • • • • • • • • • • • • • • • • • • • • • • • • •• 2

2. Log of boring showing location of samples •••••••••••••••••••••••••• 3

3. Cumulative curves of samples 20908· 20916 • • • • • • • • • • • • • • • • • • • • • • •• 5

4. Median grain size, heavy minerals and arborial pollen • • • • • • • • • • • • • • • • •• 7

TABLES

Table 1. Mechanical composition: statistical parameters. •• 9

2. Percentages of heavy minerals 10

3. Percentages of arborial pollen ............................•...... 11

Abstract

A series of cores was obtained from a boring inthe sediments of the Delaware River near the Dela­ware Memorial Bridge. The mineralogy, texture andpalynology of these samples have been studied. Thesedimentary and palynological records suggest thatthe Delaware River, while swollen with Wisconsinmeltwarers, deepened its channel and that subse­quent flooding of the mouth of the stream by risingsea waters initiated the deposition of estuarine siltsin post-Wisconsin time.

Introduction

A set of cores taken from a test boring for a pro­posed bridge adjacent to the present Delaware Me­morial Bridge between New Castle County, Dela­ware and Salem County, New Jersey, provided anopportunity to study the sediments accumulating inthat portion of the Delaware River estuary. Thenature of these sediments is significant as a studyof a depositional environment, as an inq uiry intothe geologically recent history of the Delaware Riverand also because of the economic effects whichthese sediments may have on the maintenance ofnavigation channels, the shell fisheries, and thequality of ground water drawn from wells along theshores of the Delaware. The present study must beconsidered as a preliminary investigation for it dealsonly with a single point. Areal studies of muchgreater magnitude will be necessary to achieve amore complete understanding of these sediments.

The boring from which the cores were taken islocated 200 feet north of the centerline of the exist­ing bridge and adjacent to its west tower (fig. 1).This point is approximately 2340 feet from the Dela­ware shore and 1050 feet west of the center of thenavigation channel. The total depth of this boringwas 222 feet (sea level datum). Only the upper 85feet are considered here for this interval includesthe relatively uncompacted river silts and the im­mediately subjacent materials. An abbreviated logof the boring, showing the positions of the 9 coresstudied, is shown in figure 2.

At present the Delaware River is brackish andtidal at the Delaware Memorial Bridge. The chlorideion concentration of the water at this point rangesfrom less than 50 ppm to more than 2000 ppm withfluctuations in runoff, tide and wind (City of Phila­delphia and U, S. Geological Survey, 1958). Surfacecurrents average 2.4 knots during the ebb tide and1.9 knots during the flood tide (V. S. Coast andGeodetic Survey, 1961).

The writers gratefully acknowledge the help ofMr. John R. Lewis, Resident Engineer of the Dela­ware Memorial Bridge, in procuring the samples;

1.

Dr. John K. Adams, Lniversiry of Delaware, inter­preted the X-ray diffraction data, and Mr. Thomas C.Gray prepared and made a preliminary study of thepollen contained in the sediments.

Description of Samples

Each sample has been examined megascopicallyand under the srereographic microscope, analyzedto determine mechanical composition and heavymineral content and studied by X-ray diffraction toidentify the clay minerals.

MEGASCOPIC DESCRIP TIONS

Samples 20908 through 20914 (fig. 2) are identicalin megascopic appearance. They are dark gray,slightly micaceous and organic, relatively uncom­pacted silts. Thin lamellar concentrations of veryfine sand are irregularly distributed through the finermaterial. The water content of the undisturbed coreswas high, particularly in the upper samples. Thedriller. recorded little resistance to his tools whichgenerally sank through these sediments under theirown weight. These are the sediments of primaryinterest to this study for they are the most recentsediments transported and deposited by the Dela­ware.

Below the gray silt is a thin brown silt from whichno cores are available. Below this is a yellow,fine, quartz sand 8 feet thick. It is representedby sample 20915. Some small pebbles were reportedfrom this sand by the driller.

Sample 20916 is a dense and compact light grayclay with some streaks of red. It is the uppermostpart of a thick seq uence of variegated and grayclays and fine-grained sands. .

MICROSCOPIC DESCRIPTIONS

Apart from the clay minerals quartz is the domi­nant component of the sediments. In the gray siltthe quartz is mainly subangular but ranges fromangular to rounded. These samples, 20908 throughthrough 20914, also contain organic debris and smallamounts of mica, chert and glauconite. Very fewlithic fragments were found.

Sample 20915 is a "clean"sand containing quartzand a little chert. The quartz is angular.

The sand size fraction of sample 20916 consistsalmost entirely of very angular quartz. The onlyother mine rals noted were heavy minerals which arecomparatively rare.

DELAWARE

.!. - ......- ... - -.... __ JIlL._"'_

DELAWARE

,,-- ----- ......../,,,,,

/-r',

II

rLOCATION OF BORING

CENTERLINEPROPOSED BRIDGE

RIVER

NEW

JERSEY

Figure I. Location of boring studied in this report

------..,...-~------ sea level

SAMPLE NUMBER DEPTH DESCRIPTION

Silt, dark gray

Silt, brownSand, medium, brown

Clay, variegated

Water

_.=:_ 96

__-_-:.== 36 feet----------

36·3841-4346·4851-5356-58----__~ _61 -63---J:: _66 -68----It.~~~::71

~~::~ 88~r97·99

20908209092091020911209122091320914209152091620922

..........:._---

-­.........- - ---Silt and clay, gray withsome layers of fine sand

'::'F.rn 132

/ii!;::r:.;:/:;'·:::':~166

Sand, fine, gray

Clay, variegated

~:.: 190., "..:..... . ' . Sand, fine, gray with~~::~.;.":. lenses of silt and clay

.:;.:....~ 222 total depth

Figure 2. Log of boring showing locations of samples

MECHANICAL ANAL YSES

T he sort ing coefficien ts, od», show a ten dency toincre a se (indicat ing poo re r sorti ng) with decreas inggra in s ize. Skewness val ues for all samp les but209 14. a re small and positi ve . Sampl e 209 14 i s ne ga­ti vely skewed.

Sa mpl e 2091 6 i s a clay with a medi an g ra in si zeof 8.4 1q,. T he overly ing qu artz san d (sample 20915)i s a fine sand with a me dian grai n size of 2. 38 4>.The unco mpacted material s above are all s il ts e x­cept for th e de epest s ample , 20 91 4., wh ich i s a clay(Mdq, ~ 8.23). Wi th the ex ception of sampl e 20910,th e medi an grain s i ze decreases with increasin gdep th through the s ilt.

The s tat is ti c al parameters for e ach s amp le areg iven in table 1. Because of the very fine textureof the sediments ¢ 84 did not fall within the limitsof the cumul ative freq uency curves in all case s,Values li sted as estimated are based on extendedcurves. Calculati ons of a¢ and a¢ based on theseestimate s are , of cours e , also approximate. Thee rrors introduced in thi s mariner are thou ght to bein significant for the purpose of thi s in vestigation .

Some of the feature s of tourmaline, z irc on, horn­blende and garnet have been not ed. About one­fourth of the tourmaline gra ins in th e s il t a nd clayare rounded. Tourmalin e found in th e sand was al­most entirely an gul ar. Nearly a ll o f th e tourmalineexamined was pl eochroic «( to eo) brown or re ddi sh­brown to black or ye llow to brown. G ra ins pl eo­chroic gre en to dark green, blu e to green and gra yto blue o ccur ve ry rarel y. In the deeper cl ay thebro wn to bl a ck gra ins a re do minant over yellow tobr o wn gra ins and in th e si It s and s and the y areroughl y evenl y di vi ded. In each samp le about halfof the zirco ns are roun ded and half are angular.Ro und ed zircon cannot be considered as an indexo f tr an sportation because it i s known from freshcrys tall in e ro ck s of t he Piedmont. P ink z irconsocc ur very rarel y throughout the section s tudied.One-third o f the garnets in the s i lts are essentiallycol orl e s s. App roximately 70 percent of t he horn­blende whi ch i s so abundant in (he s ilts , is gre en.The r~maining hornb lende is brow n or pleochroicfro m blue to green with t he forme r case more com mon.

The hea vy mine ra l suites from the deep clay, thesand and the upper sil ts a re some what different.The heavy mineral co ntent of each sample i s gi venin ta bl e 2. T he ' clay has a restricted suite with ave ry high st aurolite COnte nt and rel ati vel y l argeamoun ts o f tourmaline and z ircon. The sand has amuc h more varied s uite incl ud in g hornblende, garnet,kyanire , fi brol ire, hyp erst hen e, tourm aline, stauro li te ,s i ll ima nit e and zircon in order o f de c reas ing abun­dan ce. The heavy minera l suites from each o f t hesamples of s ilt (20908 throu gh 20914) a re very simi­l ar. All are domin ated by ho rnb lend e , which e xc eeds50 ·percent of the non- opaque minera ls in each c as e.L e s ser amounts of to urmali ne, zi rcon, garn et, s ill i­manite and fibrol it e as we ll as other relat ivelyscarce mineral s are p resent.

the grains. The he avy fraction was s eparated bycentrifuging the sample s in terrabromoethane (S.G .2.92) then freezin g the lower portion of th e c ent rif­uge tubes and de canting th e li ght fraction. Themethod of separation i s e s s enti ally th at described by

Fes senden (1959). Between 100 and 150 non-op aq uegra ins were identifi ed fo r each sample using t heline count method (Doeglas, 1940).

aq, Mq, - Mdq,

aq,

1/2 (q, 16 + q,84)

aq, 1/2 (q,84 - q,16)

where

Mechani cal an al yses of all samples were madeu sing V. s. s ta nd ard s ie ve s for the sand s i ze s andhy drometer met hods for the finer sizes. The re sultswere plotted as cumulative grain size distributioncurves which are shown in figure 3. The gra in s izeis meas ured in phi (q,) unit s (Knimbein, 193 4). Val­ue s are recorded from the curves at the 50th pe rcen­tile for the media n gra in size (Mdq,) and at the 84 th(q,84) and 16th (q,16) percent il e s one s tanda rd devi­ation ei the r s id e of the mean. Measure s o f the sort­io g (a¢) and skewness (aep) were calcul at ed usingthe formulae o f Inman (1952):

HEAV Y AIINERA L ANALYSES

The s i ze grades o f very fine, fin e and medium s and(6 2tL - 500tL) from t he me ch anical anal yses were u sedfor the he a vy mine ra l sep ara tion s. The samp leswere boil ed 10 minutes in dilute hydr ochloric a ci dand th en in d ilute nitri c ac id to remove coat ings on

It s houl d be not e d t hat hypersthene, which i s arelativel y un stabl e mineral no t usually found in t hes ediments of th e Coasta l P la in, has s urv iv ed weath­ering in the source a rea and tr a ns port ation to th:s ite of depo sition. All samples except 20916 co n ramthe full heavy min er al s uite defined by Dryden andDryd en (l96?).

4.

98

95

90

80

70

60....Z&LI0a:&LIQ.

~------_._-----~~

,"

-----.-/'

10

5 20908------- 20909-e- 20910- ...- 20911-x- 20912

20913-ee_ 20914----- 20915-- 20916

-I o 2 3 4

II5 6 7 8 9

Figure 3. Cumulative curves of samples 20908- 20916

CLA Y MINERALOGY

The clay minera logy was investigated by the X~

ra y diffraction te chn iq ue. Sample 209 16 containedkaoli ni t e with sub sidiary amounts of ill ite. All ofthe oth er s a mple s contain illite, chlorite and l esseramounts of kaolinite.

PLANT MICROFOSSILS

Pollen were recovered fro m s a mple s 20908 to20911 ( incl usive) and from samples 209 13, 209 14and 20922. At le ast 150 tree poll en fro m eachsample were det ermine d except fro m sample 20914,in which onl y 104 arboria l poll en were encounteredand from s ample 20922 which i s of Cre taceous age.The re s ult s of the pollen count are presented in tabl e3 and in fi gure 4.

The vegetat io n represented by a s ig nificant nu m­ber o f a rbo rial pollen con si st s of Pinus (pine),Tsu[!,a (hemlock), Carya (hickory) and Quercus (oa k).The virtual absence of Picea (spruce) and Abies(fir) should be noted,

Apart irom the some what anomalou s sample 209 10,a general increase in the percentage s of Quercusand TSlLRa po llen o ccurs from the bottom to the topof t he Recent s ed iments; th is is a ccomp anied by age ne ra l decrease in th e percentage of Carya po llen.

Amon g th e non - arborial po ll en the fami li e s Grami­neae, Compc s ira e and Cheno podi aceae a re repre­sented, a s we ll a s sp o res of the ge nera Srha{{'lum,Lycopodium, and Osmundu, and th e family Poly­podia ceae. Th e p er cent age s o f non- ar bori a l po llena re ra th er low, s ugges t ing a we ll-developed for e st

ve get ation .

Dis cussion

It i s po s sibl e to characte rize the age relat ion­sh ips o f the samples s tudied. On t he basis of grosslithol ogy sample 2091 6 and the section o f clays,silt s and fi ne sands below it may be co rre lated withthe no nmarine Cretaceous deposi ts re ferred to th ePotomac Group . The high s taurol ite heavy minera ls uite of th is sample i s t he same as that whi c h Groo t( 1955) called t he " P atuxent zon e " o f the non~ arin.eC re taceous sedime nts. Po ll e n and spores idenri­fied from samp le 20922 (97 - 99 fr.} incl ude the fol­lo win g genera: Appendicispo rites, Cicntricosispo~..ites Glei chenii di le s, /..,y copodiu msporit es, Del tot..do s~ora, Concavisporites. CinRulatisporites, E~com­miidit es and Abietine ae polleni tes. A f~w gra,lns ~ fTricolnoooll eni tes micro munu s an d po s s ib iy 1 . ren­fonni s we re found, but fe rn spo re s and gym nospe r.mpollen far e xc e ed the an gi osperm po.lIen bo t h ~nnumber of species a nd nu mber of sp e c irnens. T hi s

sporomorph assembra~e s UJ: ,I; CSt li an Albian RAe..The pa lynology. l irholog y, heavy mine ral suite,s tratigraphic and geograph ic po sicion leave littledoubt regarding the co rre lation of thi s unit .

Sa mple 20915 resemble s . litholog icall y, knownPlei stocene sands in Delaware an d th e heavy miner­ai s ui te diffe rs f ro m the s uites o f tho se sand s onlyin th at it co nta ins more hyp ers thene and le ss ep i­do t e . These cr iteria and th e use o f a s ing le sam p lec annot yi e ld defini ti ve r e sult s but it may be saidth at the sand does not re s e mbl e known pre-P le isto­cene deposits and is probably Quaternary.

The s ilrs are c onsidere d as the depositional prod­ucts of the late st phase in the development of theDelaware River a nd Bay.

The borings at the Delaware Memoria l Bridge s it eindicate t hat th e soft s il ts ar e 30 to 40 feet t hi ckthrough out a vall e y e s sential l y co inciden t wi t h thepre sent co urse of th e Delaware. Beyond the margin sof th i s va lley th e s il t th ins rapi dl y l an dw ard an dsometi me s changes to peat . The bo rings near e stthe center o f the vall e y we re ma de in about 37 feetof water ; therefor e, at th e start of the de position ofof t he se silt s the c hann el of th e Delawa re was ap­proxim ately 70 feet be low present sea l evel. Oneother locali ty known to th e writers co n firms th iss i tuat ion. Borin gs mad e wher e U.S . Route 13 cross e sDrawyer' s Cre ek , wh ic h flows into De laware Ba y16 mile s sout h of the Memorial Bridge, rev e al edth at s oft s i l ts containin g organ ic matter ex tend to

more than 60 feet below presen t sea le vel.

The most recent sediments at the Delaware Me­morial Bridge si t e are remarkabl y unifo rm in miner­a logy and do not vary greatly in texture (se e fig . 4).It ma y be said that conditions at thi s po int , and inth e Delaware Rive r generally , have bee n fairly st a­bl e s ince t he start of the depos ition of the s il ts .

On the basis of t he s e fe w samples l itt le can besaid re gardi ng the provenance of the sil ts . .T hefull s ui te of heavy minerals with many fresh miner­a ls of metamorphic a nd igneous orig in seems toindicate a major contribution from t he P iedmont .T he glauconite grains found in t he s ilts are almos tc e rta in ly not authigenic fo r this environme nt isq uite d iffe rent from t hat in which glauconit e isknown to fo rm (Cloud, 1955). T he glauconite re pre­sents a contrib ution from s treams flowin g into t he

lower part of th e Delaware R iver from the Ne w

Jers e y Coastal Pla in .

T he se young s ediments are fin e grained enough,especially near th e bottom, to ac t as an. imperme.ableba rr ie r aga ins t brack ish wa ter entenng aq uifersc ross ing under the Delawa re River. Ho we ver, the

6.

HEAVY MINERALS (%) ARBORIAL POLLEN (%)MEDIAN GRAIN SIZEMd p'

123456789 25 50 75 100 25 50 75 100

371 I '~ ' , ,

47

\

I I I I

~I

"

'I]

"

I I

:J: 62I-a.wo 67 ~

///~------

LEGEND

DIII HORNBLENDE~ TOURMALINE

~ GARNET F ~ ZIRCON

E2ZI STAUROLITE ~ SILLIMANITE aCJ OTHER HEAVY FIBROLITE

MINERALS

~PINUS

III]] QUERCUS

c:J OTHER

ELZ1 CARYA

~ TSUGA

20915

20916

Fi gu re 4. Media n 9ra in size, heavy minerals and arborial pollen

l atera l ext ent of the s il ts i s not known nor are thecffects of dredg ing. Also, in th e ir pre s ent s atu­rated, relatively uncompacted condition th e ionscontained in th e bracki sh water might po s sibly dif­fuse through the silts .

Int erp retati on of the po llen record s hould be donewi th extr eme cauti on, becaus e only a few, rath erwidely separa te d samples are involve d, and alsobecause the pollen do not nece ssarily reflect theveget ation in the immediat e vicini ty of th e site ofdeposit ion . Owing to tr ansport a ti on by the wa ter ofthe Delaw are River, some of th e poll en may havetravell ed a considerable distan ce: th e rather po ors tate of preservation of P inus and Tsuga, the formeroften wi th its a ir bladders removed, suggests a tran s­portat ional history a t least of th e s e rwo genera.

Th e preval en ce of Cary a, Quercus and P inu s , andthe absence of Pi cea and Abies , even in sample20914, s trong ly sugge sts that deposi ti on of the s il tsin the Delaware River in north ern Delaware di d notbe gin immediately after the la st phase of Wisconsinglaciation . Rather , it s ta rt ed after cli mat ic co n­dition s had ame l iora ted to s uc h an extent th at abroad leaf fores t had e st abl i shed it s elf.

Considerin g the well kno wn fa ct th at Pinus is aprofuse pollen produ cer and is o ft en over- representedin poll en di agram s , the rather hi gh percentage~ ofCarya in sa mples 20914 and '20913 may be pa rncu­larly s ign ificant . T he s e hi gh pe rcent ages suggestcorrelation with the Cz zon e o f po llen diagrams of

eastern No rth America (Deevey, 1949). It is evi­dent that the a -zon e, or th e zo ne with a high per­cent age of Pinu s, i s not pre s ent . Considering tha t

the P inus maximum occurred 9000 to 6000 ye ar s ago,dep en din g on lat itude (F lint an d Deevey, 1951), wecan state wi th reasonabl e certa inty that depositionof the silt did not be gin until 8000 years ago, andpe rhaps more recentl y. Such a rath er recent begin­ning of deposition wou ld not be su rpri s in g if it isremember ed that sea level had to rise con siderablysi nce th e end of Wi s con s in time in orde r to init iatees tua rine dep osi t ion a t thi s si te .

A post-Wis consin age i s a l so req ui red by thedepo s itional hi s tory of th e s ediments. During theperiod of lowered sea level accompanying the great­es t exten t o f Wisconsin glaciation the mel twarersfrom the ice front flush ed the De laware Riverch annel of any previ ous accumula ti on o f river s ed i­ment s whi ch may hav e been pr es ent. At thi s tim eth e ch annel in the Cretaceous s edime nt s was C ut to

it s present de pth of ab out 70 feet be lo w present s ealevel. T he s and of s ample 2091 5 may repre s ent ap art of the detri tus depos ited by th e stream dur ingthe waning phase of th e Wisconsin. With the meltingof th e contin ental glaciers th e ri sing sea drow nedthe low er ch annel of the Del awar e an d now servesto ch eck the ve locity of the s tream an d cause depo­s ition of the fin er detri t us (probably includi ng floccu­la tion of the cl ay) carri ed by th e so mew hat sh runkens tream.

The interpretat ion offe re d abov e is tenta t ive I be­cause only few da ta are available at p resent. How­ever, a s ystematic inve sti gat ion o f the sediments ofthe Del aware River an d Bay could undo ubtedly con ­t ribut e greatly to a fuller unders ta nd ing o f the lateQua te rna ry hi stor y of the area.

8.

Table 1.• Mechanical composition: statistical parameters

Sample Deptha¢>Number (SLD; feet) ¢>16 ¢>84 Md¢> (I¢>

20908 36-38 2.98 7.65 4.44 2.34 0.371

20909· 41-43 3.14 9.0 5.95 2.93 0.040

20910 46-48 4.41 9.6 (ese.) 6.40 2.60 0.234..

20911 51-53 3.75 8.90 6.18 2.58 0.054

20912 56-58 4.73 10.0 (esr.) 6.75 2.64 0.231

20913 61-63 4.90 10.5 (e st.) 6.95 2.80 0.267

20914 66-68 4.92 11.0 (esr.) 8.23 . 3.04 -0.088

20915 78-80 1.30 3.59 2.38 1.15 0.060

20916 82-84 4.95 13.0 (est.) 8.41 4.03 0.138

9.

....o

Table 2 • Percentages of heavy mineral s

........

16

41 '()

s 1 41 .~ 41 ~41 -0 41

... e 1,5

i'-'

1 'Ii! 41 's 'fi 41 "§ 41 j 1 s ~...::l 41 1 .B j i... 41 ~

~J... 'S I 1 J

'Ii! !Sample Depth, 0 IB ~ ~

t.t.~ ~-< ~ ::.:: (Jj r)1 r;<

Number (SLD; feet)

20908 36-38 1 1 10 3 67 4 1 4 1 1 4 1 2 1 24.5

·20909 41·43 4 1 3 8 4 53 5 1 6 1 3 5 2 4 1 17.6

20910 46-48 4 2 1 7 7 52 2 3 4 5 3 4 1 5 1 27.7

20911 51-53 2 4 1 3 9 3 56 4 2 2 2 2 3 4 1 28.4

20912 56-58 1 1 3 1 5 52 3 1 1 5 5 4 10 1 6 47.8

20913 61-63 1 1 5 8 54 3 1 1 4 4 4 6 8 1 54.6

20914 66-68 2 2 1 1 1 4 5 54 4 1 1 6 7 6 2 4 48.1

20915 78~80 2 1 1 3 18 19 8 10 7 9 8 8 6 33.7

20916 82-84 2 2 3 4 1 4 2 4 41 26 12 95.1

(Figures given to nearest per cent)

Table 3.• Percentages of arborial pollen

,....c:... ..... IU

0 ....ro~oeu ..0ro ro e 0..IU

Ul eu ro .5 atu::l c: '"0

'"0Sample No. ro Ul ro Ul ro u Ul ro ro c: .:; ro ....., ....ro ...IU ::l Ill) ::l "3 ... ::l ro ... >- Ul . n. 0u .5 ::l e ... eu E .... Ul ... "«l t7' Ul ~

<:..0and Depth .... ro ro e-, eu.... Ul :< eu ::l ;3 .... ::l ....c, c, I-< !Xl 0' I-< U U ...... ...J Z .... Z ~-

20908 37' 40 14 1 1 23 1 18 1 1 33

20909 42' 1 45 15 1 2 20 1'5 1 P :PI

20910 47' P 64 25 P P P 10 1 26

20911 52' 34 9 3 4 28 P P P 20 P 1 18

20913 62' 47 7 P 1 16 P P 26 P P 24

20914 67' 50 6 2 1 11 29 1 64

P • Present, less than 1%.

11.

Referen ce s

C ity of P hil adel phia and U. S. Geological Survey, 1958 , C hemica l characterist ics o f theDel aware River: Annual Report 1958.

C loud, P . E., Jr. , 1955, Ph ysi cal li mit s of glauconite formation: Am. As soc. P etroleum Geol.Ilull., v , 39, p. 484-492.

Deeve y, E. S. , 1949, Biogeography of th e P leis to cene: Geo l, Soc. Am. Bu ll. , v ; 60, p. 1315·1416.

Doeglas, D. J. , 1940, The importance o f heavy mine ral analysis for reg ional sedi ment arype tro logy: Nat . Research Counci l, Comm. Se dimenta t ion Rep t , 1939--1 940, p, 102· 121.

Dryden, I.., and Dryden , C. , 196 ? Atlantic Coastal P lain heavy mine ra ls : a speculativesummary: P roc. 20th Inte r. Geo l. Co ngo ( in pre ss).

Fessenden , F . W., 1959 , Re moval o f heavy l iq uid s eparate s from gla s s cent rifuge tu be s :Jour. Sedimentary Petrology, v. 29 , p. 62 1.

F li nt , R. F. , and Deevey . E. S., 1951, Rad iocarbon da t ing o f L ate P le is tocene events:Am. Jour. Sc i ., v, 249, p, 257-300.

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