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Journal of Coastal Research Fort Lauderdale, Florida Fall 1995 Multiple Pliocene-Quaternary Marine Highstands, Northeast Gulf Coastal Plain-Fallacies and Facts Ervin G. Otvos Geology Section Gulf Coast Research Laboratory Ocean Springs, MS 39566-7000 ABSTRACT _ .tllllllll:. ass •• - ,,0 "-"-2 W OTVOS, E.G., 1995. Multiple Pliocene-Quaternary marine highstands, northeast Gulf Coastal plain- Fallacies and facts. Journal of Coastal Research, 11(4),984-1002. Fort Lauderdale (Florida), ISSN 0749- 0208. Claims persist in the literature alleging multiple pre-Sangamonian Pleistocene, mid-Wisconsinan, middle and late Holocene marine highstands on the northeast Gulf coastal plain. These views, still encountered even in official publications are rooted in the assumed similarity between Atlantic and northeast Gulf coastal history. A critical re-examination of the evidence is based on detailed sedimentary, microfossil, and geomorphic data from hundreds of drillholes and field sampling. Sediment data were matched with basic diagnostic criteria of depositional facies. Deposits and landforms that developed during the peak of Sangamonian transgression yielded the only evidence for higher-than-present Quaternary sea levels on the northeast Gulf. Pre-Sangamonian marine units are absent in the subsurface and not exposed in coastal plain surfaces. Post-Pliocene uplift and erosion had removed littoral and nearshore units from the northeast coastal plain. Upland ridges, mistaken for relict barriers, are elongated, high interfluves. Composed of alluvial deposits, they are bounded by semiparallel lineaments of apparently tectonic origin and incised by stream erosion. Combined with lineaments, rare covered karst depressions on a late Pleistocene alluvial plain provide the slight relief of subdued linear features that had been mistaken for relict barrier islands, associated with multiple Pleis- tocene highstands. Claims for wide Holocene sea level oscillations and record highstands rest on the belief, unsupported by reliable sediment data, that the upper ridge lithosomes were essentially wave-built, intertidal and directly correlatable with sea level positions. However, the ridge morphology and dimensions clearly indicate the foredune origins of discussed Florida Gulf shore strandplain ridges. Cited texture parameters and sedimentary structure types also fail to lend independent diagnostic support to the intertidal origins of the highest beach ridge intervals. Wave-cut scarps and associated supratidal narrow terraces yield no independent proof for the postulated high eustatic Holocene sea levels. ADDITIONAL INDEX WORDS: Beach and foredune ridges, sea level indicators, shore features, coastal scarps and lineaments, covered karst, strandplains, Silver Bluff shoreline. INTRODUCTION Statements on the presence of multiple Plio- cene-Quaternary high marine terraces and wave- cut scarps, suggested indicators of elevated sea levels on the northeast Gulf plain, keep reap- pearing in the coastal literature (e.g., RUPERT, 1991; DONOGHUE and TANNER, 1992). Such claims are based on landform interpretations, including correlated elevations. Flat coastwise surfaces, lin- ear ridges and steep slopes, apparently of tectonic and/or erosional origin, have been diagnosed as marine littoral landforms. COOKE'S (1931) original Atlantic terrace des- ignations (Penholoway, Talbot, Pamlico, Silver Bluff), while in fact not applicable to the Gulf coast (OTVOS, 1972) keep recurring even in official publications (e.g., RUPERT, 1991). 94150 received and accepted in revision 30 July 1994. The purpose of this paper is to review claims for several late Neogene and Quaternary littoral lithosomes. Strandplain ridges, cut terraces and scarps are also evaluated as alleged indicators of record sea levels and sea level oscillations during the mid- and late Holocene. Higher-than-present eustatic Gulf stands, as proposed in certain pub- lications, would drastically alter presently ac- cepted sea level curves. DISCUSSION: ALLEGED LATE NEOGENE AND PRE-SANGAMONIAN PLEISTOCENE SHORELINE INDICATORS Late Neogene Units and Landforms The coastal Pleistocene in Mississippi and Al- abama is directly underlain by a thick undiffer- entiated Neogene alluvial sequence that includes thin intercalated brackish units. The Pliocene age of this sequence locally is indicated by marine

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Journal of Coastal Research Fort Lauderdale, Florida Fall 1995

Multiple Pliocene-Quaternary Marine Highstands,Northeast Gulf Coastal Plain-Fallacies and Facts

Ervin G. Otvos

Geology Section

Gulf Coast Research LaboratoryOcean Springs, MS 39566-7000


.tllllllll:.ass•• •- ~ ,,0"-"-2 W

OTVOS, E.G., 1995. Multiple Pliocene-Quaternary marine highstands, northeast Gulf Coastal plain­Fallacies and facts. Journal of Coastal Research, 11(4),984-1002. Fort Lauderdale (Florida), ISSN 0749­0208.

Claims persist in the literature alleging multiple pre-Sangamonian Pleistocene, mid-Wisconsinan, middleand late Holocene marine highstands on the northeast Gulf coastal plain. These views, still encounteredeven in official publications are rooted in the assumed similarity between Atlantic and northeast Gulfcoastal history. A critical re-examination of the evidence is based on detailed sedimentary, microfossil,and geomorphic data from hundreds of drillholes and field sampling. Sediment data were matched withbasic diagnostic criteria of depositional facies.

Deposits and landforms that developed during the peak of Sangamonian transgression yielded the onlyevidence for higher-than-present Quaternary sea levels on the northeast Gulf. Pre-Sangamonian marineunits are absent in the subsurface and not exposed in coastal plain surfaces. Post-Pliocene uplift anderosion had removed littoral and nearshore units from the northeast coastal plain. Upland ridges, mistakenfor relict barriers, are elongated, high interfluves. Composed of alluvial deposits, they are bounded bysemi parallel lineaments of apparently tectonic origin and incised by stream erosion. Combined withlineaments, rare covered karst depressions on a late Pleistocene alluvial plain provide the slight relief ofsubdued linear features that had been mistaken for relict barrier islands, associated with multiple Pleis­tocene highstands.

Claims for wide Holocene sea level oscillations and record highstands rest on the belief, unsupportedby reliable sediment data, that the upper ridge lithosomes were essentially wave-built, intertidal anddirectly correlatable with sea level positions. However, the ridge morphology and dimensions clearlyindicate the foredune origins of discussed Florida Gulf shore strandplain ridges. Cited texture parametersand sedimentary structure types also fail to lend independent diagnostic support to the intertidal originsof the highest beach ridge intervals. Wave-cut scarps and associated supratidal narrow terraces yield noindependent proof for the postulated high eustatic Holocene sea levels.

ADDITIONAL INDEX WORDS: Beach and foredune ridges, sea level indicators, shore features, coastalscarps and lineaments, covered karst, strandplains, Silver Bluff shoreline.


Statements on the presence of multiple Plio­cene-Quaternary high marine terraces and wave­cut scarps, suggested indicators of elevated sealevels on the northeast Gulf plain, keep reap­pearing in the coastal literature (e.g., RUPERT,

1991; DONOGHUE and TANNER, 1992). Such claimsare based on landform interpretations, includingcorrelated elevations. Flat coastwise surfaces, lin­ear ridges and steep slopes, apparently of tectonicand/or erosional origin, have been diagnosed asmarine littoral landforms.

COOKE'S (1931) original Atlantic terrace des­ignations (Penholoway, Talbot, Pamlico, SilverBluff), while in fact not applicable to the Gulfcoast (OTVOS, 1972) keep recurring even in officialpublications (e.g., RUPERT, 1991).

94150 received and accepted in revision 30 July 1994.

The purpose of this paper is to review claimsfor several late Neogene and Quaternary littorallithosomes. Strandplain ridges, cut terraces andscarps are also evaluated as alleged indicators ofrecord sea levels and sea level oscillations duringthe mid- and late Holocene. Higher-than-presenteustatic Gulf stands, as proposed in certain pub­lications, would drastically alter presently ac­cepted sea level curves.



Late Neogene Units and Landforms

The coastal Pleistocene in Mississippi and Al­abama is directly underlain by a thick undiffer­entiated Neogene alluvial sequence that includesthin intercalated brackish units. The Pliocene ageof this sequence locally is indicated by marine

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Gulf Coast Marine Highstands 985

Figure 1. Index map ofalleged pre-Pleistocene ("A"-through­"C"; + 80 m- to-+ 35 m) and Plei stocene; Tates Hell ("D ";+ 9 m and + 6 m) shorelines (DONOGHUE and TANNER, 1992;Figure O.

of Late Pleistocene and Holocene Atlantic andGulf strandplain complexes (OTVOS, 1985) onlylocally exceed 2-4 km, while ridge summits rarelyrise more than a few meters above the adjacentalluvial or lagoonal deposits of approximately thesame age. The late Pleistocene Gulfport barrierstrandplain sectors provide good examples. Theirridge elevations rarely exceed 2--4 m over the swalefloor or the adjacent alluvial surface of compa­rable age.

GA--- ---~--- --------


o '"I(J~S




"Marine Terraces", Northwest Florida Uplands

DONOGHUE and TANNER (1992) reiterated ear­lier assertions by GREMILLION and others (1964),TANNER (1966), and WINKER and HOWARD(1977),regarding the "relict ocean shoreline" origins ofupland surfaces, i.e., plains, ridges, scarps, andswales between the Escambia River and penin­sular Florida. Inland, not far from the coast, ridgeelevations range between 35-50 m, and accordingto Winker and Howard, on both sides of the Ap­alachicola River reach c. +100 m (Figure 1). Setsof semiparallel topographic ridges , flanked bycreek valleys, led to the interpretations of inter­fluve ridge groups as relict barriers. WINKER andHOWARD (1977) acknowledged that these conclu ­sions were solely based on large-scale topo graphicmap features, not field studies.

The flat-topped interfluves are 2-8 km wide. InWinker and Howard's "Gadsden ridge sequence"in areas of Bristol and Hosford USGS Quadran­gles, in sharp contrast with real barrier strand­plains, upland ridge summits rise 15- 24 m aboveadjacent valley floors. In contrast , the total widths

microfossils and pollen (OTVOS, 1991, 1994; WIL­LARD and EDWARDS, 1994). Eastward, toward andwithin northwest Florida, the siliciclast ic Neo­gene sequence gradually becomes less alluvial andmore marine. Miocene and Pliocene carbonateunits appear and thicken (OTVOS, 1992). Alluvialsediments (in cluding a Pliocene alluvial se ­quence) form an upland surface that adjoins thenarrow Pleistocene coastal plain (Table 1).


Coastal wetlands , lagoonal , inlet , fresh and brackish water delta deposits. Mainland andHOLOCENE island barr ier strandplains, beach complexes, alluvium.

w WISCONSINAN Eolian inland dune ridges (Blue Mt. Carrabelle area) Valley fill alluviumzw GLACIAL~g:5§

SANGAMONIANPrairie Fm. (alluvial) Gulfport Fm. (barrier complex)

~ Biloxi Fm. (neritic-to-estuarine deposits)n.INTERGLACIAL Undifferentiated earty and pre-Sangamonian alluvial deposits

w UPPER Citronelle Fm. (in uplands only)zw

MIDDLE0 Undifferentiated alluvial and marine siliciclastics0:J

LOWER Perdido Key Fm. (AL-FL border area) Jackson Bluff Fm. - Intracoastal Fm.n.


I!:!ffi UPPER Choctawhatchee Fm. / Stage:5~ Pensacola Fm. (=? part of Intracoastal Fm.)::;

J ournal of Coastal Research, Vol. 11, No.4, 1995

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Field studies indicated that interftuve ridges inwhat Winker and Howard called "Escambia,Wakulla, and Gadsden Shoreline Sequences" arecomposed of laterally and vertically variable, verycoarse-to-fine, silty-sand siliciclastic deposits.These units represent the late Pliocene CitronelleFormation between northwest Florida and Mis­sissippi (OTVOS, 1972). In Georgia and adjacentFlorida areas, a correlative unit was named theMiccosukee Formation (HlJDDLESTlIN, 1988). 'I'heupland interfluve ridges reveal much greater ver­tical relief and wider spacing than the littoralstrandplain ridges. In terms of sediment content,texture and textural variations, morphology anddimensions, they bear no resemblance to littoralbarriers.

The strongly mottled alluvial Citronelle com­plex contains abundant peds, fragipans, burrows,root casts and other structures, indicative of in­tensive paleosol development. Shallow subtidalMiccosukee lithofacies include Uphiomorpho tracefossils in Georgia and adjacent Florida east of theApalachicola River (HUDDLESTlJN, 1988, and per­sonal communication, 1994). However, no littoralbarrier facies identified by homogenous sand lit h­osomes, well- to very well sorted, are known fromthe Citronelle-Miccosukee upland surfaces.

GOETSCHIUS (1971) produced the only note­worthy, if unsuccessful, attempt to document lit­toral marine origins of northwest Florida uplandssurfaces with granulometric data. He analyzednumerous sediment samples from Liberty andGadsden Counties outcrops at various elevations,without adequate stratigraphic control. Despitethe absence of associated brackish or marine fos­sils, GOETSCHIUS assigned these surfaces to threedesignated "marine terraces". Intervals that sep­arate sandier "barrier" Iithosomes, because of theirgreater mud content and poorer sorting, were des­ignated relict lagoons. GOETSCHlllS admitted thathis "barrier" sands, not as well sorted as Recentbarrier sands, are well within the sorting range ofnearby modern stream channel sands.

Following WINKER and HOWAHD in placing in­tertidal designations on ridges of comparable al­titudes, DONOGHUE and TANNEH (1992) main­tained that the "Gadsden Sequence" is "roughlycorrelatable with the Trail Ridge sequence" of thenorthern Florida peninsula. However, the TrailRidge is of entirely different origin. It consists ofwell sorted dune sands with occasional placers,representing a large coast-parallel, transgressivedune complex, decoupled and transported fr0111


its original shore locations (FORCE and RICH,1989;FOHCE, 1991).

In contrast, the cited Florida upland ridge se­quences are erosional in origin (OTVOS, 1972). Theywere incised deeply into late Neogene alluvium,apparently carved along semi-parallel tectoniclineaments that developed into stream valleys.Sedimentary and/or fossil evidence for C}ssociatedmarine, estuarine, shoreface, and intertidal/su­pratidal littoral (barrier) deposits is absent.

Tectonic Scarps and Lineaments (IS. Marine

Terraces and Wave-Cut Bluffs

Sedimentary and fossil evidence for "wave-cut"interpretation of Citronelle and Pleistocene scarpsis also missing. No littoral sediments, associatedwith wave deposition, have been reported fromscarp toes. Relict barrier ridge slopes are generallygentle, rarely as steep as the cited upland valleyslopes, cut into fluvial deposits. Steep slopes likethose cut into Citronelle redbeds south of Tal­lahassee, at Pensacola, Florida and in Mississippi­Alabama, apparently follow fault scarps thatbound Citronelle upland surfaces on the south.The continuity, linearity and relatively fresh ap­pearance of Citronelle scarps suggest their tec­tonic origin (OTVOS, 1981).

Structural lineaments also occur in the latePleistocene Prairie coastal' surfaces as finelyetched, parallel lineaments. Lateral continuitybetween the coastal Mississippi Big Ridge Scarpand adjacent contiguous, fine lineaments on thePrairie surface (OTVOS, 1981) offer strong evi­dence for their tectonic origins.

Pleistocene Coastal Stratigraphy, Northeast Gulf


In correlating south Atlantic coastal plain ter­races with alleged marine terraces and scarps onthe northeast Gulf and the Mississippi Embay­ment, COOKE (1945, 1966) correlated comparabletopographic elevations of level (H1narine terrace")surfaces and scarp faces on maps, disregardingunderlying deposits. This followed COOKE'S pio­neering designation of seven Atlantic coast ma­rine terraces, valid indicators of relict shorelinesand associated lagoonal deposits.

MACNEIL (1950) and others followed in Cooke'sfootsteps in attempting to map Gulf coastal plain"terraces" without credible sedimentological,stratigraphic, fossil, and morphological criteria.Having been trapped by Cooke's elevation criteriafor marine terraces, MAHSH (1966, Fig. 22) felt

.lournal of Coastal Hescarch. Vol. II, No.4, H)9f)

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Gulf Coast Marine Highstands 987

compelled to map "Penholoway Sea" deposits atPensacola, Florida, drawing the "Sangamonian"shoreline in Citronelle alluvial redbeds at t 21 rnelevation.

Subsequent coastal plain studies (OTVOS, 1991;OTVOS and HOWAT, 1992) led to stratigraphic re­visions on the basis of sedimentary and geomor­phic characteristics of coastal lithofacies (e.!?,

DAVIS, 1983; REINgCK and SIN(~H, 1992, and oth­ers).

Pre-Sangamonian Pleistocene Shorelines?

The presence of multiple Gulf coastal plain lit­toral lithosomes, in the proximity of well-docu­mented generations of littoral and paralic depos­its ("marine terraces") on the Atlantic coastal plainof Florida and Georgia appeared so plausible afterCooke's early work (19~11) that it is still taken forgranted by some ie.g., HEALY, 1975; Rt lPEHT, 1991;DONOGHUE and TANNEH, 1992).

Designations of "marine" terraces and associ­ated "wave-cut scarps" usually were solely basedon compatible elevations and superficial morpho­logical similarity. with littoral features alone. Amap of northwest Florida's coastal and inland sur­faces that defines "marine terraces" rigidly byelevation intervals is one example (HEALY, 1975).

It shows the entire Panhandle area between 0-- 45m elevations as underlain by one of COOKE\;, ter­race surfaces (from oldest to youngest; Hazel­hurst/Brandywine, Coharie, Sunderland, Wicom­ico, Penholoway, Talbot, Pamlico, and SilverBluff). According to our own studies, only a smallfraction of the Florida Panhandle land area isunderlain by (Sangamonian and Holocene) lit­toral marine sediments, the rest by late Neogeneand Pleistocene alluvium.

The tectonic setting of the Gulf coastal plainmay explain the absence of pre-Sangamoniancoastal barrier ridges and associated depositionalfacies. On the northeast Gulf, the uplift of the lateNeogene Citronelle alluvial plain to 70-100 mnorth of the narrow Pleistocene coastal plain re­sulted from a broad regional movement, accom­panied in the entire area by deep, steep erosionalgully and stream incision. Except for limited coast­parallel terraces of alluvial origin (OTVOS, 1991),

surface erosion stripped the region of all pre-San­gamonian Pleistocene littoral and nearshore rna­rine units. Geodetic leveling is (HOLI)AHL andMORRISON, 1974) indicated, even today, by upliftnot far inland from the present shore.

Sangamonian Coastal Complex

Studies on the northeast Gulf coast utilizingdata from several hundred coreholes revealed thepresence of only a single transgressive-regressivePleistocene sedimentary cycle (OTVOS, 1972, 1981,1991). Deposits of the cycle overlie undifferen­tiated Pleistocene or Neogene alluvium and near­shore marine Neogene (OTVOS, 1992). All threemajor components (the alluvial Prairie, the ne­ritic-to-paralic Biloxi and the Gulfport barrier de­posits) are well developed on the ApalachicolaCoast, as well as along the rest of the northernGulf shore (OTVOS, 1992; Figure 3b; Table 1).

Early Sangamonian sea level on the Apalachi­cola Coast stood at 37 m, possibly - 48 m. Biloxidepositional facies range from inner shelf to high­ly brackish inshore environments. Biloxi sedi­ments onlap Prairie alluvium, also interfingeringwith and overlain by the Prairie along the Biloxi'slandward "featheredge".

Continued regional uplift inland lifted Prairiesurfaces well above the Sangamonian peak eus­tatic sea level of c. t 6 m. In north Hancock Coun­ty, Mississippi, the Prairie surface graduallyreaches +18 m elevation; in northwest Florida itrises above +9 m (OTVOS, 1992).

Barrier strandplains of the Gulfport progradedduring the Sangamonian eustatic highstand andthe early stage of the following regression. Scat­tered references in the literature to the barriersegments as "islands" notwithstanding, drillingin landward direction turned up no evidence yetfor Late Pleistocene lagoons (e.g., Figure 2).

Apalachicola Coast "Relict Immature BarrierIsland Chains"-Indicators of Multiple LatePleistocene Highstands?

Superficial map interpretations gave rise to theidea of the Tates Hell Swamp "barrier islandtrends". MACNEIL'S (1950) original idea of "Pam­lico" - (Prairie) age islands has periodically reap­peared in the literature (e.g., DONOGHUE, 1992,and D()NO(~HtIE and TANNEH, 1992, p. 235). Drillsample studies and a reexamination of topo graph­ic features refutes the validity of this approach(OTVOS, 1990a, 1992).

The alleged Pleistocene island chains 16-20 kminland were portrayed as two, 100-400 m wide, c.10 km long arcuate "sand bodies" in Tates HellSwamp, separated by a distance of 5 km (TANNER,1966). Based on their linearity and perceived to­pographic expression, the "sand bodies" were des-

•Journal of Coastal Research, Vol. 11, No.4, 199[)

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988 Otvos

Gulf of Mexico

GUlfport Fm.

Prairie Fm.

Wisconsinan eolian r-;--,sand dunes L...!......J



,".11f-(·~:::.;f. 33 ··.34~·"'·.:-:,·: ~.•..J:..v;;:;;.::-.;;.-::i;.a~ . ':"-....;. ..1 •••:.:3~~~-

1- .'~.•~-=-- Apalachicola

31 St. v; ~A./29 30 "ce"t I". Bay , 39

~~ 01 5 10km ~ <In.0 B'~v . I , G00 ' 'tJ




Inland "rldqes"

Figure 2. Apalachicola Coast Pleistocene units, NW Florida. Drillhole locations and surface geology (OTVOS, 1992).

ignated as remnants of two (+6 m and +9 m)Pleistocene shorelines. TANNER claimed that the"relict island" bodies rise 1-4 m above the adja­cent plain. Correctly, BRENNEMAN (1957) men­tions only 60-120 em surface relief, associated withthese narrow, discontinuous slightly elevated stripsof ground. Brenneman's sediment samples, takenfrom just below the land surface, revealed poorsorting. Abandoned logging railroad embank­ments, located on these strips, slightly enhancedthe ridge elevations (Figure 4, right).

A detailed study of 36 Apalachicola Coast drill­cores and surface geology (OTVOS, 1992) indicatedthat Tates Hell Swamp is directly underlain byfossil-free, poorly-to-very poorly sorted oxidizedsilty sands and sands of the Prairie Formation.Neogene siliciclastics and carbonates occur be­neath (OTVOS, 1990a, 1992). The Prairie, at 12­14 m depth is underlain by karstified Late Neo­gene carbonates that rise near the land surfacetoward the southeast.

If the Tates Swamp "sand ridges" were relictbarriers, they would be associated with Sanga­monian marine littoral and paralic units in the

surface and subsurface. However, while littoraldeposits are well developed along the mainlandshore, they are absent from the Tates Hell "ridge"areas (Figures 2 and 3A,B). Corehole #6, drilledthrough the northern "ridge", for instance, didnot encounter any marine or brackish deposits.The muddy Prairie sands in the boring were iden­tical in composition and appearance to Prairiesands elsewhere and did not represent discretelinear sand bodies.

BRENNEMAN and 'TANNER (1958) invoked amassive influx of muddy delta deposits to explainpoor sorting of these "not extensively reworked,immature barrier island deposits". Poor sortingwould be most atypical of beach sands on evenrelatively low energy, nonglacial shores, for in­stance Louisiana's. However, from kurtosis valuesof the muddy sands alone, and DONOGHUE andT ANNEH (1992, p. 2:)5) paradoxically assumed, notlow-energy but "moderate to high wave energy",condiLions for the inferred island shores.

Slightly raised Tates Hell "ridges" actually werepartly related to dissolution processes in shallowunderlying carbonates. Covered karst develop-

Journal of Coastal Research, Vol. 11, No.4, 1995

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Gulf Coast Marine Highstands 989

A A'

wsw ENE








10 km
















29 30



-ISO '



8 N 5 E




5 6 TATES HELL SWAMP 12 18 44 45 46 39.10






ml,10 km

Line 8

Figure 3_ A,B. Apalachicola Coast cross sections. A- -thick Pleistocene sequence, overlying the Neogene sequence, Cape San Blas­Apalachicola River cross section: B- -T ates Hell Swamp cross section, Note thick Prairie alluvium and absence of non-terrigenousPleistocene deposits (Orvos, 1990, 1992) in Drillhole n6, alleged site of one " immature barrier island".

Journal of Coastal Research, Vol. II, No, 4, 1995

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990 Ot vos

Figure 4. Left and right. Pr oir ie alluvial coas tal su rface with covered ka rst morphology, USGS Tates Hell Swamp Orthoph otoQuadrangle, NW Fto rida , 198 1. O- irregu la r ly sha ped , sha llow depress ions; S - circu lar a nd ova l sinkhole depressions. " Ridge ' setsI and 2- frac ture-tfan ked, d iscon ti nuous, s ligh tly eleva ted nar row bel ts (alleged " bar rie r island " gen erations of MACNEIL, 1950;BRENNEMAN and TANNI.:n, 1958; and OONO<: HIIIi and T ANNP.R, 1992). Arr ows without letters po int to s traight, fra cture-defineddepression rim s. Contours in mete rs.

.lour nal of Coasta l Resear ch , Vol. II , No.4 . 1995

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Gulf Coas t Marine Highstands

Figure 4. Continued.


ment manifests itself in interconnected broad, ir­regular, amoeba-shaped surface depressions (Fig ­ure 4, left and right), previ ously unreported . Thelargest, less than 1-2 m deep, are 4.5- 8 km wide.Numerous oval-cir cular sinkhole outlines, 150-300m in diameter were imprinted in rim s and floorsof the large shallow basin s (Figure 4,Ie ft and right).

Straight depression rims revea l a rectangularfracture network. Parallel frac tures bound nar­row, slightly elevated, slightly better drained andtherefore ligh ter-toned zones. As slight " in ter­fluve highs", they sepa ra te adjoining depressions.Discon t inu ous, flat- topp ed stri ps on aerial pho­tog ra phs and topog raph ic maps created the false

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appearance of high, elongated ridges (Figure 4,left and right).

These unique features mark the only northernGulf Pleistocene coastal area with covered karsttopography. The young drainage network is stillpoorly integrated. On the northern Gulf, coveredkarst with deep depressions was previously re­ported only from nearby Citronelle uplands (OT­VOS, 1976).

Adopting COOKE'S approach to terrace desig­nation on the Apalachicola Coast, HEALY (1975)and RUPERT (1991) combined Sangamonian ma­rine barrier sectors with those of extensive Prairiealluvium, under the heading "Pamlico marine ter­race". They also merged parts of the PleistocenePrairie ("Pamlico") plain with Late Holocene andRecent barrier and subaerial delta surfaces. Thisunusual blend of disparate surfaces was labeledthe "0-10-ft Silver Bluff Terrace"; its age, des­ignated as Pleistocene or Holocene.

Mid-Wisconsinan Highstand?

Although uniformly dated worldwide at 135­105 ka, highest deposits of the last marine (San­gamonian) highstand, on occasion, have been as­signed to the Mid-Wisconsinan (BRENNEMAN andTANNER, 1958) and sediments of the second youn­gest highstand, to the Sangamonian Interglacial(e.g., MARSH, 1966, for other references, In: OTVOSand HOWAT, 1992). In the upper Midwest wherethe idea originated, the concept of a mid-Wiscon­sinan interglacial has long been discarded. Morerecently and without more validity, the briefFarmdalian interstade (c. 28-24 ka BP) in themidst of the Wisconsinan glaciation has been mis­takenly identified by some (In: OTVOS and HOWAT,1992) as a time of a sea level that closely ap­proached the present one.

Alleged Mid-Holocene Record Sea Levels

Cooke and MacNeil were among the first tosuggest extreme high mid-Holocene sea levels onthe southeast Atlantic coast. Later, PARKER andCOOKE (1944) introduced the term "Silver Bluff"in southeast Florida for a late Pleistocene wave­cut scarp, thought to be indicative of raised (+1.8­3.0 m) sea levels. Between Wakulla County andPensacola, Florida, MACNEIL (1950) tentativelycorrelated a "Silver Bluff shoreline" with a pos­tulated + 1.8-2.4 m sea level, associating it withthe mid-Holocene climatic optimum, 6-4 ka BP.

Fairbridge repeatedly claimed mid-and lateHolocene record sea levels on the Gulf and At-


Iantic coasts. His mid-Holocene + 2 m sea levelon a Miami area reef platform (FAIRBRIDGE, 1992)is based on the carbonate fraction of apparentlyreworked sand, associated with much youngermangrove roots. This unit is actually located with­in the present intertidal zone (see: HOFFMEISTERand MULTER, 1965, p. 874), not above the presentintertidal range.

WHITE (1970) believed that at its Miami typelocation the Silver Bluff formed in part and isbeing maintained by occasionally recurring stormwave erosion.

The existence of a high "Silver Bluff" shorelineand associated lithosomes could not be verifiedon the Gulf seaward of the Sangamonian littoralcomplex. Sea level data (e.g., NELSON and BEAY,1971; OTVOS, 1991) also indicate that between 6and 4 ka BP sea level rose from c. -7 m, to - 3 m.

Suggested Evidence for Middle and LateHolocene Highstands

Shore Scarps and Small Incised Terraces. STAPOR(1973,1975) described scarps and associated smallterraces at +1.5-3 m above sea level, cut in Pleis­tocene barrier ridges at several Alabama andnorthwest Florida locations. His belief in mid­Holocene highstands in part was based on thefresh appearance of a high mainland scarp in NWFlorida that faces an archeological site, seaward.The site included Norwood fiber-tempered ce­ramics of 3-4 ka BP age (STAPOR, 1973; BRALEY,1982). Because it was thought incapable of out­lasting a postulated record transgression abovepresent sea level, the Indian midden was consid­ered to postdate the scarp.

However, survival of the archeological site initself does not represent credible evidence. Noassociated and dated littoral sediments were foundto prove the alleged highstand. At the same time,hundreds of Indian sites, regularly exposed tostorm erosion, still endure in intertidal-low su­pratidal shore zones. Several sites, presently ex­posed on the flat inner shelf floor had not beeneliminated even by the overriding transgression(e.g., DUNBAR, et al., 1992).

A narrow cut-terrace of Magnolia Bluff, on theeast bank of the Apalachicola estuary, carved fromGulfport barrier sands was similarly cited in sup­port of the late Holocene highstand. DONOGHUE(1993) dates its development as preceding that ofApalachicola Bay by barrier islands that emergedc. 4 ka BP. In this view, wave intensities dimin-

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Gulf Coast Marine Highstands 993

Figure 5. Erosional terrace and scarp, cut into Late Plei st ocene barrier at c. 0.9-2 m above sea level. Narrow Mississippi Soundbeach. left. East Belle Fontaine Beach, Missi ssippi.

ished afterward , precluding scarping and terracecutting.

Mainland shore bluff scarps, including that of12 m high Royal Bluff cut into a large dune (OT­VOS, 1992), however, testify to highly erosive stormevents even on relatively protected bay shores.Storm surges here reached +2.4 m during the1972 and 1985 hurricanes.

A similar, narrow incised terrace at +0.9 to +2m elevation illustrates the same point on Missis­sippi's mainland shore. The small Belle FontaineBeach terrace in Jackson County was also carvedby storms from Gulfport barrier sands and hu­mate-cemented sandstones. Approximately 100 mlong and 0.5-6.5 m wide, it is bracketed by the 1­2-m backshore bluff on the Mississippi Soundshore and a lower scarp, in landward direction(Fig. 5).

Another "marine terrace", regarded as high­stand indicator by STAPOR (1973, 1975) at Pen­sacola Naval Air Station in northwest Florida,

occurs off the Gulfport barrier toe . In contrast, itis an aggradational feature. Actually, it is thesurface of a late Holocene dune strandplain thatrises to + 1.5- + 3.0 m elevations. Naturally, thissurface is unrelated to record Holocene sea levels,except indirectly to the cur rent one.

In Search of "Highstand" Sediments

Wave-Constructed Ridges; Eolian and SwashLamination. TANNER and STAPOR (1975, 1991) andSTAPOR et al . (1989, 1991) asserted that strand­plains of Florida beach ridges formed essentiallyby wave runup and swash-backwash deposition,not eolian processes. Differences in ridge set el­evations were thus attributed to oscillating LateHolocene sea levels. Narrow, often steep activeforedunes on west Florida's Lee County barrierislands, on St. Joseph barrier spit and other Ap­alachicola Coast strandplain shores have been re­jected as alternate models of ridge development.Statistical parameters of sedimentary textures and

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994 Otvos

Figure 6. Horizontal and gently cross- lam ina ted eol ian sand layers that mimic foreshore lamination. Active dune field, cut byretreating 2-3 m Gulf backbeach scarp. East of Dauphin Island Fishing Pier, Alabama. (Scale units: in and em)

certain structures were invoked as tools in distin­guishing between eolian and subaqueous littoralfacies .

Distinguishing Subaqueous Facies by TextureParameters. TANNER (1991) used mean , sorting,skewness and kurtosis st.atistics, and statisticalparameter cross-plots to interpret fifty-nine St.Vincent strandplain ridge sam ples as intert.idal inorigin . Low skewness values of sample sets wereclaimed as hallmarks of "mature" beach, not ofeolian sands. Crossplots of kurtosis and sortingvalues were correlated with topographic low andhigh ridge sets. Low ridges were viewed as markersof marine lowstands, tall ones as highstand in­dicators.

One major objection t.o this approach is the lackof objective, empirical field comparison and ver ­ification, based on a sufficiently large number ofsamples, obtained from a variety of modern de­positional environments. While TANNER assertedthat in most beach ridges the eolian sand com­ponent amounts to 5-20'10, the method and itstheoretical foundations on which t.he intertidal

and eolian sand ratios were established also re­main unclear and therefore unconvincing.

In addition, the plotting of averaged group val­ues ("suite statistics") not of individual samples,prevents recognition of overlaps between eolianand intertidal sample fields on the diagrams. Thismay lead to preconceived and arbitrary facies as­signment of certain samples to given facies cat­egories before their statistical parameters are sub­mitted t.o further calculations.

Facies Identification by Sedimentary Structures.Parallel and low-angle cross laminae, describedfrom the Apalachicola Coastas examples of "swashzone bedding". occur in beach ridges as high as 3m above mean sea level (STAPOR, 1975). Near­horizontal , parallel- and low-angle cross stratifi­cation was postulated to be an intertidal feature.This infers their formation during a higher-than­present Holocene sea level stage (STAPOR et al.,1991, Figure 5).

However, these sedimentary structures are notrestricted to intertidal sands. Laminae in eolianridges may mimic the semiparallel bedding and

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Gulf Coast Marine Highstands 995

low-angle cross lamination in the beach foreshore(DAVIS, 1983, Figure 12-11). This happens in dunecuts, perpendicular or at low angles to the sandtransport direction. As one example, an erodingbackbeach scarp that cuts through a very exten­sive and active dune complex at Dauphin Island'sFishing Pier, Alabama, exposes the very same"beach"-lamination types 2-3 m above Gulf level(Figure 6).

In addition, during temporarily elevated sealevels not accompanied by significant erosive ac­tivity, swash action by large, constructive swellwaves may deposit low-angle cross.-stratified setsand horizontal, planar swash laminae on land­ward- and seaward beach ridge slopes (see also:Figure 14, HEQUETTE and RUIZ, 1991).

Geomorphic Argument. Origins of the ShellComponent

Narrow, 2-4 m sand ridges of well sorted, white,medium sand, typical of Holocene mainland andisland Gulf strandplains, clearly are not wave­built intertidal berm (swash) ridges (Figures 7A,B).The uneroded, steep slopes of relatively very re­cent strandplain ridges (e.g., Figures 7A,B) testifyto their beach foredune origins. Eolian aggrada­tion is the only mechanism that builds such ridgesappreciably above high tide level under normalwave conditions. When the wind-transported or­igin of the upper ridge lithosomes is recognizable,only the base of the eolian interval, related to thesea level during the ridge-forming time interval,acts as a constraint in marking sea level positions.It defines the maximum elevation of the under­lying intertidal ridge interval.

The presence of large shell fragments in coastalridges especially on shell-rich, quartz sand-starvedshores, may not be explained by eolian transportmechanism, only by locally nondestructive over­wash processes. Large, constructive swell wavesovertop dune ridges during raised sea level epi­sodes. Shelly sand layers lodged on dune surfaces,as in the past on southwest Louisiana's cheniers,occasionally contributes to ridge aggradation.



Central West Florida (Lee County) BarrierIslands

STAPOR et al. (1987,1991) assembled numerousradiocarbon dates from six barriers. The islands

are very low, generally of 1.2-2.7 m ridge eleva­tion. Vertical exaggeration of the cross sectionscreates the impression of steep ridge slopes (Fig­ure 8, right). Ridge top elevation values and ra­diometric dates were offered as proof for higher­than-present Holocene Gulf levels.

None of the fossil beach ridge sets on the islandswere considered eolian by these authors, and theirsummit elevations were regarded directly corre­latable with late Holocene highstand episodes.Stapor and others (1991; their Figures 6a,b, 14)cited the "Wulfert" and "La Costa" (Lacosta; CayoCosta) ridge generations, with elevations thatmatch those of current foredunes (Figure 8, leftand right), as evidence for a + 1.2 m marine high­stand between 2-1.5 ka BP.

Equally puzzling, other ("wave-built"?) ridges,formed as recently as the last century when eu­static sea level was slightly lower than presently,apparently were also related to + 1-3 m marinehighstands (Figure 8, left and right).

In agreement with Stapor and others, that thehighest "swash" island ridges formed during rec­ord marine highstands, DONOGHUE and TANNER(1992, p. 239) seized on Stapor's 3.0-2.7 ka dates,claimed by him as derived from the highest ridgesand thus reflecting +2.4-3.0 m Holocene high­stands. It is noted, however, that the cited dateswere obtained not from the highest but lower (0.6­1.5 m) ridge sets (see: STAPOR et al. 1991, Figures2,9, 14).

As with other Gulf coast examples, the conclu­sion that at least the upper ridge lithosomes (Figs.7a,b) are eolian in origin and the ridge summitsare only indirectly related to late Holocene sealevels, is inescapable.

St. Vincent Island Strandplain; Ridge Elevations,Ages, and Island Genesis

(a) Ridge Elevations and Sand Granulometryas Perceived Indicators of Sea Level Fluctuations

Sizable St. Vincent Island (Figure 2), locatedoff the Apalachicola Coast west of the Apalachi­cola Delta in northwest Florida, is the site of oneof the most spectacular Gulf coast strandplains.It is composed of a number of ridge generations.

Utilizing their previously cited approach thatbased on granulometric statistics assigns intertid­al origin to beach ridges and directly correlatesridge summit elevations with sea level stands,TANNER and coauthors postulated seven-to-ninesignificant sea level changes during island devel-

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996 Otvos

Figure 7. A,B. Examples of steep-sloped late Holocene strandplain ridges; relict foredunes-not intertidal berm (swash) ridges.Apalachicola Coast, NW Florida. A-northeast of Cape San BIas Plantation, E of Drillh ole 30 locat ion (Figure 1 in Or vos, 1992);B-just south of entrance to Peninsula State Park, central St. Joseph Spit (S of Drillhole 21, Figure 2). Ridge elevations: c. 3.5-4 .0m above road level (Orvos, 1992).

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Gulf Coast Marine Highstands 997

opment (e.g., STAPOR, 1975; TANNER et al., 1989;TANNER (1991), DONOGHUE and TANNER, 1992).

(b) Ridge Elevation Differences and LocalizedSubsidence

In contrast with the 4.5-5.7 m (15-19 ft) max­imum ridge elevations in the younger southernisland area, the generally subsea-to- + 1.2 m ele­vation range of the northern ridge tops seem in­fluenced by differentiated and in part localizedcompactional ridge subsidence into underlyingmuddy sediments. Highly conspicuous lateralvariations in elevation within given ridge sets mayin part have the same origins.

Due to the great morphologic and size similar­ities between the least eroded, youngest strand­plain ridges and present active beach foredunes,there is little doubt about the essentially eoliannature of the beach ridges. They may reflect pastsea level stands only indirectly.

(c) Island History; Archeology and BeachRidge Chronology

Radiometric Dates. Two shell dates, both fromthe northeastern island corner (BRALEY, 1982, andSTAPOR, 1975), were the only ones published fromthe island.

The first originated from one of the culturallayers of the sizable Paradise Point shell mound;Site 8Fr71 (1320 yr BP; corrected to 1710 yr BP;BRALEY, 1982, p. 38). On archeological grounds,BRALEY expressed some misgiving about the date'sdependability. STAPOR (1975) and following him,BRALEY (1982) believed that the date reflects sealevel rise that partially drowned the mound. Asubsequent sea level decline was also assumed.

Compactable and thick underlying muddy unitsmay have contributed to subsidence of the mound.The slightly elevated position of muddy depositsof unknown origin, over one cultural layer, is hardlyan independent proof for elevated sea level stage.

The second dated sample available from theIsland (c. 2110 yr BP; STAPOR, 1975), from theMallard Slough shore area, was from quartz sandtaken near the eroding east terminus of a beachridge. The sand may have come from a shallowsubtidal interval, located beneath a subsequentlyremoved ridge sector. A 5 m thick, compactable,"soupy" mud unit underlies the sand (Stapor,written comm.; OTVOS, 1992, p. 230).

Despite the lack of associated absolute dates,TANNER (1993a) suggested that a large part of theisland, a 1 km wide Ridge Set G, bracketed be-

tween two, somewhat higher, wide ridge sets (map:TANNER, 1993a, Figure La), formed during a sub­recent "Little Ice Age lowstand".

Starting c. 1450 A.D., this cooler interval lasteduntil the first half of the 19th century (VAN ANDEL,1981). In other views, it was more restricted (1570­1730 AD; e.g., SCHOVE, 1987, p. 359). Certain de­tailed historical records (e.g., TERS, 1987, p. 209)strongly indicate that these climate fluctuationsdid not appreciably, or even recognizably impactglobal sea levels.

TANNER (1993a) proposed ridge-set correlationbetween St. Vincent and a north Danish strand­plain. In view of the substantial isostatic read­justment and other factors that affected Scandi­navian shores, the correlation is highlyproblematical.

New Orleans Barrier Trend-Mid-HoloceneHigh Sea Level Evidence?

A buried mid-to-late Holocene barrier complex,composed mostly of shallow subtidal sand litho­somes is covered by late Holocene delta depositsunder eastern New Orleans, Louisiana. Ridgesummits at a few locations extend above sea level(+0.5 m in New Orleans and at Lake St. Cathe­rine, to the east).

STAPOR et al. (1987, p.152; 1991, p. 833) mis­takenly cited OTVOS (1978) as suggesting that ex­posed ridge summits and perhaps high subsurfacesand lithosomes, apparently suspected by Staporas intertidal in origin, reflect amid-Holocene, c.5 ka BP, marine highstand. Shallow submarinedeposits, including bars and shoals, occur in theshallow subsurface. Identifiable shallow subtidaldeposits do not occur above present sea level.

Exposed sand bodies, strongly altered by soilprocesses have been considered relics of supratid­al, eolian bodies that probably capped islands thatwere part of the barrier complex (OTVOS, 1978).Portions of the dune lithosomes may have sub­sequently subsided below Gulf level. A compli­cating factor is the uncertain rate of still con­tinuing subsidence. Judging from historic subsi­dence rates based on tidal gage records; they var­ied considerably within the New Orleans area(OTVOS, 199Gb).

Louisiana Cheniers-Postulated Proof of LateHolocene Record Highstand?

Employing granulometric parameter crossplotsand ridge elevation-sea level correlation in Louis­iana's chenier plain, DONOGHUE and TANNER (1992,

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998 Otvos

E --~~-+---- E I





Beach ridge patterns (diagrammatic)= _=_==_--- Constructed 1860-1952- ------~~ Constructed Prior to 1860

Calcarenite exposures •


Sampling Sites 1Indian site @

Pleistocene (?) dune





I U5 0 I km

~-- ..

c==J Sanibel I (3000-2000 Yr. BP)

1:::::::::::::1 Wulfert (2000-1500 Yr. BP)

[>::::::~'::::-J Buck Key (1500-1000 Yr. BP)

c=J La Costa (1000-500 Yr. BP)

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Gulf Coast Marine Highstands 999

A/RIDGE.S BUILT 1860-1950 A'



O.5km1- --',

B{RIDGES BUILT 1860-19509' \-. [[]

6'~~- " ._ . 10



r_ . =.~


BUCK KEY (1500-1000 YR. BP)

LA COSTA (1000-500 YR. BP)



I ;\: 1


I ii SANIBEl I (3000-2000 YA. BP)

2 m 1:::;:::;:::;:::;1 WULFERT (2000-1500 YR. BP)

3000 FEETI




M SL L-,..;-:";':"-;'_,-,-..;......

Figure 8. Left and right. Late Holocene and historic beach ridge sets, Lacosta (La Costa, Cayo Costa) Island, central West Floridacoast (after STAPOR et al., 1991). Left-map of ridge generations; right-profiles across Island. Gulf shore on left . Compare "high­sea level" Wulfert set summit level, section C with number 2; historic (subrecent) ridge sets.

p. 239) and TANNER (1993b,c) concluded that sealevel oscillations of 1-2 m, respectively, 1-6 m(!)amplitudes did typically take place in the pastthree thousand years. Chenier ridges formed dur­ing Late Holocene highstands; inter-ridge lows,during lowstands.

Detailed lithofacies and biofacies studies(BYRNE, et al., 1959, Plate 2; and other publica­tions) revealed simple vertical and horizontal fa­cies relationships of the Louisiana chenier com­plex. Microfossil and lithofacies data establishedthe depths and shore positions of subtidal-near­shore and inner shelf-bay facies. Intertidal facieswere also identified in ridges and interveningmudflats and marsh deposits.

The consistently shallow depths of subtidal­intertidal depositional facies provides ample ev­idence for a quite stable late Holocene sea level

during chenier and mudflat progradation. Thepostulated major swings between low- and high­stands would translate into onlap/offlap relation­ships. These would be drastically different andmore complex than what is well established fromdrill data (BYRNE et al., 1959). Highstands, inaddition, would have also laid down Holocene sed ­iments far north of the present seaward limit ofPleistocene surface deposits.

Record high Holocene sea levels would not berequired to explain the large proportion of shelldebris in chenier ridges. Shell debris occurs ashigh as 3.3 m (11 ft) above mean sea level in OakGrove Ridge chenier (750-850 AD; BYRNE et al.,1959, Fig. 8), although most cheniers reach only1.2-2.0 m above mean sea level. Those had beenmore often impacted by overwash.

As to a much lesser extent in Lee County, Flor-

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ida, non-erosive wave action, probably large swells,during temporarily raised sea levels lodged abun­dant shell debris on dune slopes on this quartzsand-starved coast. Landward-dipping washoverlaminae, also illustrated by KACZOROWSKI (1978),added large volumes of shelly sand to the chenierridges.

Suggested Evidence from an AlabamaArcheological Site: Inferred High Holocene SeaLevels

HOLMES and TRICKEY (1974) described threemud layers, sandwiched between radiocarbon­dated cultural horizons in an Indian mound onTensaw River, c. 42 km inland from Mobile Bay.An episode of mud deposition at +0.6 m, at onetime between 4100-3090 yr BP, and another at+1 m, in the 2040-3090 yr interval coincided withtimes of assumed highstands, marked in a 1961sea level curve.

Two high sea level episodes, associated withmud-emplacing flood events were suggested.However, tropical storm tides in Mobile Bay orrecurring river floods from inland may well ac­count for a minor stream level rise, a logical al­ternative to longer-term sea level fluctuation. Thusfar, this highly isolated archeological data fail tomake a convincing case for record Gulf highstandlevels.


Despite a sizable body of literature publishedsince C. W. COOKE'S pioneering Atlantic coastcontributions six decades ago, valid evidence ex­ists only for a single Pleistocene highstand. A fewpre-Sangamonian Pleistocene coastwise terraceremnants, composed of alluvial deposits have beenidentified. Most alluvial and all marine units havelong been stripped by erosion during the still con­tinuing regional uplift that raised the late Plio­cene alluvial plain of the coastal uplands to + 75­90 m (OTVOS, 1991, 1993). Attempted correlationsof pre-Sangamonian southeast Atlantic littoralfeatures with northeast Gulf coastal surfaces andother allegedly littoral landforms were based onsuperficial similarities.

The Late Pleistocene Gulfport barrier repre­sents the only Pleistocene marine unit exposed inthe coastal plain surface. It is part of the San­gamonian sedimentary cycle that includes alluvialand neritic-to-inshore members as well.

Disputed indicators of marine highstands fallinto two categories. The first involves topographic


features that mimic coastal landforms. These werecarved from alluvial deposits, often along parallelfractures of tectonic origin. Interftuve ridges and(tectonic) scarps that superficially resemble bar­rier ridges and wave-cut scarps formed, as a result.In a unique coastal plain sector with karstic land­forms, surface depressions combined with appar­ently tectonic lineaments mistakenly led to claimsof late Pleistocene marine highstands and asso­ciated shore ridges at + 6 and +9 m elevations.

The second category involves littoral litho­somes and landforms. These are equally unsuitedas Holocene highstand indicators. Despite theirbackshore dune ridge morphology, several au­thors regarded them essentially as intertidal. Sed­iment granulometry and structures provide noconvincing evidence for assuming their intertidalorigin and for relating ridge elevations to assumedsea-level oscillations.

In the absence of sedimentary and fossil evi­dence, elevated scarp toes, notches, and narrowterraces, cut into Pleistocene barrier sand ridgeson lagoonal shores, fall in the same category. Theywere excavated and maintained by recurring stormprocesses at a time when sea level did not standsignificantly lower or higher than today.

Higher-than-present Holocene littoral litho­somes are abundant in areas affected by postgla­cial isostatic rebound. Similarly, even brief epi­sodes of postulated raised sea levels would haveleft ample sedimentary proof of onlap behind. ThinHolocene littoral and paralic lithosomes of suchrecord highstands would overlie oxidized Pleis­tocene surface deposits a few feet above sea level.Their absence on the Pleistocene coastal plainrepresents a decisive argument against assumedrecord highstands. Well documented mid -to-lateHolocene Gulf sea level positions (e.g., NELSONand BRAY, 1971; OTVOS, 1991) also refute suchspeculations.


I appreciate correspondence, pertinent refer­ences, and reprints received from Drs. Stapor,Tanner, and Donoghue in the course of manu­script preparation. Incisive and highly construc­tive editorial comments by Richard A. Davis, Jr.and an unnamed reviewer were received with sin­cere gratitude.


BRALEY, C.O., 1982. Archeological testing and evalua­tion of the Paradise Point Site (8Fr71), St. Vincent

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National Wildlife Refuge, Franklin County, Florida.Report, Southeastern Wildlife Services, Inc. Athens,Ga, 102 p.

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BRENNEMAN, L. and TANNER, W.F., ]958. Possible aban­doned barrier islands in panhandle Florida. Journalof Sedimentary Petrology, 28, ~42 -~~44.

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COOKE, C.W., 1931. Seven coastal terraces in the South­eastern States. WashinRton Academy of SciencesJournal, 21, 503-513.

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