A Sand Budget For Saco.Bay, Maine

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J.T. Kelley, D.F. Belknap, D.M. FitzGerald, D.C. Barber, S.M. Dickson, S. van Heteren, L.K. Fink, and P.A. Manthorp

Maine Geological Survey Natural Resources Information and Mapping Center DEPARTMENT OF CONSERVATION

Robert G. Marvinney, State Geologist

Open-File Report 95-1 Maine Geo log i cal Sur vey Open-File 95-1

A Sand Budget for Saco Bay, Maine

J. T. Kelley Maine Geolog i cal Sur vey, 22 State House Stati on, Augusta, ME 04333 D. F. Belknap Dept. Geolog i cal Science s, Uni ver sity of Maine, Orono, ME 04469 D. M. Fitz Ger ald Dept. Geol ogy, Boston Uni ver sity, Boston, MA 02215 D. C. Barber Dept. Geolog i cal Science s, Uni ver sity of Maine, Orono, ME 04469 S. M. Dick son Maine Geolog i cal Sur vey, 22 State House Stati on, Augusta, ME 04333 S. van Heteren Dept. Geol ogy, Boston Uni ver sity, Boston, MA 02215 L. K. Fink Dept. Oceanog ra phy, Uni ver sity of Maine, Orono, ME 04469 P. A. Manthorp Dept. Geol ogy, Boston Uni ver sity, Boston, MA 02215

ABSTRACT

Saco Bay hosts the larg est sand beach and the largest salt marsh system in Maine. We con structed a sand bud get for the bay by eval uat ing the sources and sinks for sand, as well as the pathways in which this mate rial moves. Side-scan so nar and bot tom sam ples were employed to map the off shore areas, while seis mic reflec tion and vibracoring meth ods were used to ex am ine the volume of sand. On land, ground-pen etrat ing ra dar and cores were used to measure sand vol ume and stratig ra phy. Histor i cal maps and ae rial photo graphs provide d measure ments of sand move ment over long time frames, and cur rent me ters evalu ated sand movement both offshore and in the Saco River estuary. The Saco River is the main source of sand to the bay, and provide s an es timated 10,000 to 16,000 m3 of sand per year to the bay. This sand moves to the north and allows Pine Point to grow. Con struction and sub sequent enlarge - ment of the north jetty at the Saco River mouth pro foundly al tered the nor mal movement and stor age of sand be - tween 1867 and 1955. At the pres ent time, 56 mil lion m3 of sand re side in the shoreface and 22 mil lion m3 of sand are beneath the beach and dunes. This sand is all utiliz ed by the beach system, however, so that dredg ing and spoils dis- posal prac tices that do not take into consid eration the natu ral storage and movement of sand place the overall system at risk.

IN TRO DUC TION

Sand beaches are among the most im portant and valuable neer ing measures taken to pro tect some cultural fea tures com - ar eas of the coastal zone, yet they are the most rap idly chang ing monly increa se the haz ard to other devel op m ents as well as to the as well. Their at trac tion as des tina tions for rec re ational swim - beach sys tem itself. Saco Bay, Maine, is a long-es tab lished ming and boating, and their proxim ity to protec ted bays suit able coastal resort area in northern New England, U.S.A. (Figure 1) for harbors has led to the large-scale cultura l devel op m ent of that is an outsta nding exam ple of these inter acti ons. This paper most beaches. That devel op m ent is, in turn, placed at risk by its eval uate s the dynam ics of sand de posi ti on and erosion on sev- very pres ence in a dy namic coastal system . Fur ther more, en gi -

1 Kelley and others

Figure 1: Lo ca tion of the study area within the Gulf of Maine (inset map), and bathymetric map of Saco Bay. Geo graphic names and fig ure numbers re fer to those used in this re port. eral time scales as a result of both anthropogenic and natural 1609), hum an ac tivi ti es like dam, jetty, and seawall construc tion activities in Saco Bay. proba bly rival rising rela ti ve sea level as an influ ence on shore- Shoreli ne change along sandy beaches like those of Saco line be hav ior. On a time scale of a few years, hu man ac tiv ities Bay result s from an inter acti on among the rate of supply of sand, such as dredging and spoils dis posal, along with storm-gener - wave and wind clim ate, es pe cially storm fre quency and in ten - ated waves, are probably the most important factors in shaping sity, rate of rel a tive sea-level change, an te ced ent geo log i cal set- the coast (Pilkey and others, 1989; Fenster and Dolan, 1994). ting, and ac tivi ti es of hum ans (Pilkey and others, 1989). The Saco Bay, Maine is the larg est beach sys tem in north ern behav ior of the beach system over a long period of time, such as New England (Figure 1). Al though its econom y is dom inate d by the Ho lo cene Ep och, is prin ci pally gov erned by vari a tions in rec re ational pur suits to day, in the past, in dus trial ac tiv ity and sand sup ply and rates of rel ative sea-level rise (Belknap and comm er cial fish ing were the main stays of the lo cal econ omy. As Kraft, 1981, 1985). The ante ced ent geolog i cal set ting may rep- a result of its his tory, the beach sys tem is influ ence d by resent a source of sand for the sys tem and exert control on local long-term geo log i cal pro cesses, coastal en gi neer ing struc tures geom orphol ogy . Along a rock-framed coastli ne like Maine, and prac tices, and by con tem po rary rec re ational ac tiv ity. Al - bed rock out crops com monly in ter rupt long shore sand move- though the beach system is constra ined by engi neer ing struc- ment and estab li sh the geom etry of an embayment (Nelson and tures (jet ties) at the river mouths on its north and south ends and Fink, 1980; Duffy and others, 1989; Kelley and others, 1989a). several high-rise de velop m ents in the centra l beach region, this Over an in ter medi ate time frame, such as the time span since the area is not yet as intensely de vel oped as beaches on the Eu ro pean col o ni za tion of north east ern North Amer ica (circa mid-Atlantic and southeastern United States’ coast.

2 A Sand Budget for Saco Bay, Maine

Because Saco Bay is a rock-framed pocket beach sys tem, it the dune line nor seaward of the “depth of closure” (an arbi tra ry is self-con tained and un in flu enced by far-afield lit to ral ac tiv i - offshore line). These require ments, includ ing the as sumpti on ties. This iso la tion, cou pled with a rel a tively sim ple lo cal stra - that a defin able sandy profil e of equi librium actu all y exist s, tigra phy (Belknap and others, 1989a; Kelley and others, 1989a; greatly lessen the utilit y of the rule (List and others, 1991; Belknap and Shipp, 1991), render the bay amena ble to measure - Dubois, 1992; Pilkey and others, 1993). In an area like Saco ment of its sand budget over vary ing time frames. The purpose Bay, where sea-level rise is not the only factor influ enc ing shore - of this report is to evalu ate the static vol ume of sand in the major line change, the Bruun Rule is not applicable. depositional reser voirs of the Saco Bay system , includ ing the The most useful, but least appli ed, approach to under sta nd - dunes, berm, shoreface, and es tu ary, and to es tim ate the rate of ing the behav ior of beach system s involves construc ting a sand exchange of sand among these res ervoirs on geolog i cal , histor i - budget (Komar, 1983). This approach re quires that the rate of cal, and contem porary time scales. In com pil ing a sand budget sand flux to and from outside source(s) is known, as well as the we also address two working hy pothe ses: (1) that sand for the re- rate of exchange of sand among the depositional reser voirs gional beaches is derive d from an offshore glacia l source, and af- within the system (Carter, 1988). Some studies have evalu ate d ter reaching the beach, moves from north to south (USACOE, the rate of sand movem ent over lim ited time peri ods by di rect 1955), or (2) that sand for the beaches is de rived from the Saco measure m ent or by indi rect cal cula ti on of the amount of sand River and moves along the beach from south to north (Kelley and move ment us ing cur rent ve loc i ties, and ex trap o lat ing the re sults others, 1989a). over lon ger time peri ods. On a beach sys tem the size of Saco Bay, such dy nam i cal mea sure ments are pro hib i tively costly and PREVIOUS WORK may be repre sen ta ti ve of only short-term shoreli ne proces ses. We have em ployed dy nam i cal mea sure ments of beach-pro file Sand Budgets changes and offshore and estuarine sand transport only to demonstrate the relative direction of sand movement. Many previ ous studies have attem pted to ana ly ze shoreli ne Some re ports have com pared time-se ries his tor i cal maps changes to better anti ci pate the future behav ior of beach sys- and bathymetric charts of coastal ar eas to eval u ate changes in tems. In New Eng land and ad ja cent mari tim e Can ada, a con cep - sand vol ume, and to infer di recti ons of sand movem ent over the tual model de picts the co-evolu ti on of barrie r spits and attac hed past century (Hess and Harris, 1987a, FitzGer ald and others, bluffs of gla cial sedi m ent (Johnson, 1925; Boyd and others, 1989; List and others, 1991). Despit e the dif ficult y in geograph i - 1987). This model explai ns the rapid landward migra ti on of the cally regis ter ing old maps, we have em ployed vintage charts and barrie r in re sponse to the de pleti on of its sedi m ent supply (a bluff maps to make histor i cal assess ments of sand budget changes of gla cial sedi m ent) through erosion. Although Saco Bay may (last 130 years), and we have used his tori cal aeria l photo graphs once have contai ned such barri ers, the pres ent system does not to es ti mate sand vol ume changes over shorter time frames and ap pears to be more stable than those sys tems associated with (10-40 years). eroding bluffs (Nelson, 1979). Few studies have measured the volum e of sand in Bruun (1962) took a quanti tati ve approach to predict ing depositional reser voirs of the beach system even though this shoreline re sponse to ris ing sea level. His “rule” as sumed a tech nique eval u ates the in te grated prod ucts of pro cesses act ing shoreface profil e of equi librium in which the depth offshore, h, is over millen nia. In many coastal plain set tings it is dif fi cult to dis - di rectly re lated to the dis tance sea ward of the beach, x, times a tin guish be tween a va ri ety of com plex sandy de pos its re sult ing constant, A: from the re peated Quater nary fluctu ations of sea level (Ashley h = Ax2/3 and others, 1991). In gener all y muddy re gions, however , sand de pos its are clearly de lin eated by geo phys i cal meth ods and cor- To maintai n this shape as sea level rises, Bruun (1962) pos- ing, and the vol ume of depositional reser voirs are measur able tu lated the rule that: (Pope and others, 1991). Becaus e Pleis tocene sedi m ents in Saco s = (a)l/h; Bay are disti nguish able from Holo cene sand bodies with geo- physi cal techniques (Kelley and others, 1989a), we have em - where s is the amount of landward migra ti on of the beach, a is the ployed these methods, along with core stratigraphy, to measure amount of sea-level rise, and l and h are the verti cal and hori zon - the total volume of sand within Saco Bay. tal di mension s of the sys tem, re spec tively. In this for mula tion, sand is rem oved from the landward-m igrat ing beach and trans- Pre vi ous Seis mic and Strati graphic Re search in the West ern ferred to the shoreface and sea bed to main tain a pro file of Gulf of Maine equilibrium. Al though of ten ap plied in plan ning and en gi neer ing de- Ear lier re search in the re gion per mits rel a tively con fi dent signs, the Bruun Rule, even as ac knowledged by Bruun him self as sess ment of seism ic re flec tors en coun tered in Saco Bay. Pre - (1988), is a two-dim ensiona l model that assum es: (1) no long- cam brian and Pa leozoic igne ous and meta morphic rocks can be shore movem ent of sand, and (2) no losses of sand landward of traced di rectly from coastal outcrops into the subsurface and

3 Kelley and others form the acousti c basem ent of the area (Belknap and others, 1989a; Belknap and Shipp, 1991). Where bedrock crops out on the seafloor, its strong acous tic re flec tivity and frac ture pat terns are eas ily recog nized on side-scan so nar record s (Kelley and others, 1986, 1987, 1989a, b; Kelley and Belknap, 1991). Till uncon form ably rests on bedrock and is widely recog nize d from its cha otic inter nal struc ture and strong surface return in seism ic refle cti on profil es (Belknap and others, 1989a; Belknap and Shipp, 1991), and ir reg u lar, acous ti cally dark, boul der-lit tered surface on side-scan sonar records (Kelley and others, 1989a, b; Kelley and Belknap, 1991). Glacia l-marine sedi m ent, the Presumpscot Form ati on (Bloom, 1963), exhib it s a va riety of acous tic fa cies in seis mic reflec tion pro files, but is com monly acous ti cally transpar ent (GM-M, unit of Belknap and others, 1989a) with wide spread, rhyth mic, co her ent re flec tors that drape the under ly ing topog ra phy (GM-D, unit of Belknap and others, 1989a) or with weaker acous tic refle cti ons that are ponded within bathymetric de pressions (GM-P, unit of Belknap and others, 1989a). Where this mate ria l crops out on the seafloor a lag deposit of sandy gravel with ripples is visi ble in side-scan sonar records (Kelley and others, 1989a; Kelley and Belknap, 1991). In water depths less than about 60 m, an erosiona l uncon - formity exists on the sur face of the gla cial-marine sed im ent (Belknap and others, 1989a; Kelley and Belknap, 1991; Kelley and others, 1992). In many areas , acous ti cally transpar ent Holo - cene mud, often charged with acousti cally-opaque natu ral gas, rests on the transgressive uncon form ity (Kelley and Belknap, 1991; Kelley and others, 1994a; Belknap and others, 1989a). Mud of fers alm ost no acousti c return on side-scan sonar records (Kelley and Belknap, 1991). Sea ward of sandy beaches like Saco Bay, a stronger surface return from an acousti c unit often con tain ing clinoform re flec tors is in dic a tive of Ho lo cene sand (Belknap and others, 1989a). In side-scan sonar records the sand Figure 2: Rel a tive sea-level change graph for the western Gulf of Maine offers a strong acoustic return and is commonly covered with (modi fied from Kelley and oth ers, 1992; Barnhardt and oth ers, 1995).The gray en ve lope en cir cles a large number of gla cial-ma rine ripples in large fields or narrow linear bands (Kelley and others, dates not gath ered for this re port (Belknap and oth ers, 1987). Those 1989b). points la beled SC are from Saco Bay. Cores pene tra ting all of the sedi m entar y units have es tab- lished confi dence in these inter preta ti ons as well as in a chronol - ogy for the stratigraphi c units (Kelley and others, 1990, 1992, 0.5 mm/yr at 1,000 yr B.P. in southern Maine (Kelley and others, 1994a). Gla ci ation, deglaciation, and the ac com pa ny ing rel a tive 1995, Barnhardt and others, 1995; Gehrels and others, 1995). sea-level changes are the most im portant influ ence s on the geo- During the past 5,000 years of slow rela ti ve sea-level rise, logi cal colum n (Figure 2) (Belknap and others, 1987; Kelley and many of northern New England’ s coastal beaches and marshes others, 1989b, 1992). A lowstand shore line was formed around devel oped (Oldale, 1985; Belknap and others, 1989a,b; Kelley 10,500 yr B.P. near the contem porary 55 m isobath (Shipp and and others, 1995). Bar rier evolu ti on before this time of slow rel - others, 1989, 1991; Kelley and others, 1992). In outer Saco Bay ative sea-level rise was mostly transgressive in nature, as sug - the surface of this fea ture is covered with sand that we hy pothe - gested by evi dence from a num ber of nearby barri ers. At Hills size was de rived from the an ces tral Saco River (Kelley and oth - Beach and Fletcher Neck, im medi ately south of the study area, ers, 1992). Follow ing the lowstand, sea level rose rapidl y to 20 Hulmes (1980, 1981) found an absenc e of shallow-m arine facie s m depth at 9,200 yr B.P., when a signif i cant slowdown occurred in Biddeford Pool, and a 985 year-old peat sam ple collec ted at (Kelley and others, 1992; Barnhardt and others, 1995). Lit tle re- the sea ward side of the beach. She con cluded that the bar rier had cord rem ains of coastal depos it s in wa ter depths greater than 20 migrat ed landward approx i m ately 20 cm/yr during the Holo - m. The rate of rel ative sea-level rise ac celer ated around 7,000 yr cene, in the proces s rework ing proglacial sands. Sim ilar ly, the B.P., and then slowed again at 5,000 yr B.P.. Rela ti ve sea level exis tenc e of the Wells-Ogunquit barrie r sys tem in southern conti nued to slow its rate of rise to 1.2 mm/yr at 4,000 yr B.P. and Maine is relat ed in part to the erosion of the San ford outwash

4 A Sand Budget for Saco Bay, Maine plain. Sand was transporte d to the conti nental shelf during the entra nce is predi cat ed on the untes ted assum pti on that “...a con- late Pleis to cene re gres sion and sub se quently was par tially re - stant movem ent of sand from north to south along the ocean worked into bar riers (Kelley and others 1987, 1989b; Shipp, beach ... has...depos it ed mate ria l in front of the origi nal entra nce 1989). Landward migra ti on of this barrie r lithosome is indi cat ed channel” (USACOE, 1910, p. 3). The Army hy pothe siz ed that by the pres ence of salt-marsh peat be low the bar rier fa cies (Mon - eroding glacia l depos it s near the center of Saco Bay shed sand to tello and others, 1992). Radio car bon dates (Hussey, 1959, 1970; the north and south: “It appears that the beaches in Saco Bay Belknap and others, 1989b; Montel lo and others, 1992; Kelley may have been formed as spits which grew in both di recti ons and others, 1995) suggest that the Wells-Ogunquit sys tem from the high ground at Old Orchard Beach” (USACOE, 1955, formed at least by 5000 yr B.P., and reached near its present posi - p. 5.). Hulmes (1980, 1981) evalu ate d the evolu ti on of tion after 2500 yr B.P., coin ci dent with decel erat ing rates of rel a- Biddeford Pool through vibracores and be lieved that that beach tive sea-level rise. Many beach sys tems in the re gion display system also originated through the erosion of glacial sediment. evi dence of coastal progradation in the form of sea- Re search em ploy ing mod ern geo phys i cal de vices be gan in ward-younging beach ridges, closed tidal inlet s and abandoned the 1980’s. Kelley and others (1986) evalu ate d the seis mic stra - coastal lagoons, and botani cally mature salt marshes, possi bly as tigra phy of Saco Bay and inferred, based on early lower-reso lu - a re sult of the very slow rate of sea-level rise for the past two tion seis mic pro files, that a rel a tively thick de posit of sand thousand years (Duffy and others, 1989; Kelley and others, floored the bay’s bottom . They conclude d that sand from the 1993; Gehrels and others, 1995). Saco River must have been respon si ble for that great vol ume of Con tempo rary rel a tive sea-level rise in the Gulf of Maine sand as well as for the ex ten sive beaches in the area. Kelley and ranges from 1.8 mm/yr (since 1927; Seavey Island, ME) to 2.9 others (1987) de scribed the bottom sedi m ents in the region in de- mm/yr (since 1921; Boston, MA), as evalu ate d by tide gauges tail based on grab sam ples, subm ersibl e dives, and geophys i cal (Lyles and others, 1988; Belknap and others, 1989b). These obser va ti ons, and later (Kelley and others, 1989a) synthe siz ed short-term rates are greater than any long-term rates the re gion this work with Farrell’s (1972). More recent ly, cores reveal ing has appar entl y expe ri ence d in the past 4,000 years. It has been less than one meter of sand over gla cial-marine sed im ent and sug gested that this ac celer ation in the rate of rel ative sea-level higher-res o lu tion seis mic re flec tion pro fil ing data re vised rise is partly re sponsi ble for contem porary erosion of salt downward the thickness of sand in Saco Bay (Kelley and others, marshes and beaches (Ja cobson, 1988; Kelley and others, 1995). 1992). Ra diocar bon dates from core sam ples in Saco Bay also suggest ed that the lower and upper popu la ti ons of heavy miner - als in early cores from Saco Bay (Luepke and Grosz, 1986) rep- Pre vi ous Re search on the Dis tri bu tion and Move ment of Sand re sented glacial-marine and fluvial sediments, respectively in Saco Bay (Kelley and others, 1992).

Farrell (1972) prepared the first bot tom-sedi m ent map of Saco Bay based on grab samples and fa thometer traces. He spec - His tor i cal Shore line Changes and En gi neer ing Ac tiv i ties in ulat ed on eroding glacia l depos it s as form er sand sources in the Saco Bay Prouts Neck area and noted that surficial sand appeare d thin in the outer bay. Despit e his hydro graphi c obser va ti ons (Farrell, Histor i cal ly, the Saco River has been a major shipping 1970, 1972) which reveal ed that the Saco River is strat ifie d in chan nel, but the tidal delta at its mouth has always been a bar rier the sum mer, he consid ered the river as the main source of sand to to navi ga ti on. In 1827 some obstruc tions to navi ga ti on were re - the bay. He noted that the ori enta ti on of paleospits in the moved, but by 1866 it becam e nec essary to construc t a 1311 m Goosefare Brook salt marsh suggest ed a southern, riverine sand long jetty on the north side of the river entra nce to block “...a source, as did the fining of sand size along the bay’s beaches consta nt movem ent of sand from north to south along the ocean from south to north. beach, ...which has ...depos it ed mate ria l in front of the origi nal In early re ports, the U.S. Army Corps of Engi neers entra nce channel” (USACOE, 1910, p. 3). (USACOE) also con sid ered the Saco River as a source of sand, A jetty was construc ted on the south side of the river en- at least to its estu ary (“The river...dur ing spring freshets car ried trance in 1897, and the navi ga ti on channel was deepened and large quanti ties of sand, and more parti cu lar ly logs, sawdust, and both jet ties were lengthened and raised several times during the other refuse. ..[to] just be low Fac tory Is land (a water fall at the early 20th century . The north jetty is pres ently 2030 m long, 5.2 head of tide)” (USACOE, 1886, p. 5)). In all later work, the m above mean low water (MLW) for the first 259 m from land, Army inferred a gla cial or igin for the bay’s sand: “The beach and 4.6 m above MLW for the rem ainder . The south jetty is 1463 mate rial in [Saco Bay] is of gla cial de posit or igin ... Due to the m long, 3.3 m above MLW for the first 259 m, and 1.7 m above topog ra phy of the coast there is appar entl y no natu ral source of MLW for the re mainder (USACOE, 1992). mate ria l other than by local erosion within the confine s of Saco Shore line changes ac com pa nied en large ments of the jet ties Bay” (USACOE, 1955, p. 6). The construc tion and repeat ed at the river mouth. Camp Ellis grew sea ward in the late 19th cen - lengthen ing of the 2030 m long northern jetty at the Saco River tury due to changes in the hy drody nam ic condi ti ons at the river

5 Kelley and others mouth. As tidal current s at the mouth of the es tuary becam e con- METHODS fined to the dredged, jettied chan nel, the twice-daily seaward flow across the Saco River’s ebb-tidal delta ceased. Re gions on Surficial sedi m ent was evalu ate d through bot tom sam ples, both sides of the jet ties be came dom inate d by shoaling wave side-scan sonar records, and seism ic refle cti on profil es (Figures condi ti ons, result ing in the onshore movem ent of landward-m i- 1, 3a, b). All 134 offshore sam ples were gathered with a grat ing sand bars by 1877 (Farrell, 1972). This same phenom e- Smith-Mac In tyre 0.25 m3 grab sam pler, while 200 sam ples were non was docu mented at sev eral in lets elsewher e on the East gath ered in the Saco es tu ary and vicin ity with a Van Veen sam- Coast of the United States fol low ing jetty con struc tion pler. Size anal yses were per formed by sieve, settling tube, and (FitzGerald, 1988; Dean and Work, 1993). Micromeritics Sedigraph fol low ing stan dard prep a ra tion tech - After the pe riod of accre ti on owing to onshore migra ti on of niques (Folk, 1974) (Figure 3a). An EG&G SMS 260, the tidal delta and pos sibly to dredge spoils disposal , beach re- slant-range correct ed side-scan sonar was used to map 30 km2 of treat had becom e a problem on both sides of the jet ties by 1909 the sea bed (Fig ure 3a), and an ORE Geopulse seis mic re flec tion (USACOE, 1955). Although the Hills Beach side appar entl y profiler gathered 370 km of subbottom records (Figure 3b). All sta bi lized, Camp Ellis con tin ued to re cede. The Army esti mated nav i ga tion po si tions were mea sured by LO RAN-C and trans- that betwee n the north jetty at the river entra nce and a point 3650 formed to lat i tude/lon gi tude co or di nates by the com puter pro- m to the north, betwee n mean high water and the 5.5 m isobath, gram, LORCON (J. Stuart, National Ocean Survey, personal the shoreli ne lost 61,933 m3/yr of sand from 1859 to 1955, a total communication). of 5.945 x 106 m3. This does not include the addi ti onal sand in- Offshore cores were gathered with both Rossfelder (P5 and troduced to Camp Ellis beach by regu lar dredging of the Saco P6) and Al pine vibracorers from 16 sites in water depths up to 60 River navigation channel (USACOE, 1955). m (Figures 1, 3b). Of these, 6 cores were taken in water depths Shoreli ne erosion studies have often been conducte d at less than 25 m and are the only cores consid ered for this study. Hills Beach (USACOE, 1920) and Camp Ellis (USACOE, 1935, All cores were photo graphed and logged prior to grain-size anal- 1939, 1955, 1961, 1976, 1987), but found no linkage be tween yses and radio car bon-dat ing of fossil s. A Lanesky and others the jetti es and the shoreli ne changes: “The Divi sion Engi neer (1979) vibracorer was em ployed on land to provide sam ples for also con cludes that the fed eral jet ties at the mouth of the Saco radio car bon dating as well as ground-truth infor m ati on for a River have not caused nor accel erate d erosion of the shore in the ground-pen e trat ing ra dar (GPR) profiler. A Geo phys i cal Sur vey study area [Camp Ellis]” (USACOE, 1955, p. 21). The most re - Sys tems Sys tem 3 GPR was mounted on a small cart to min imize cent report (USACOE, 1992, p. 4) states that wave refle cti on distanc e betwee n the 120 MHz transcei ver and the ground and to from the north jetty “...contri butes to some extent in the erosion” maxi m ize the flexi bil ity of oper a ti on. In all, 32 vibracores were (of Camp Ellis). A $500,000 phys ical model of Camp Ellis and gathered along 40 ki lom eter s of GPR lines (Figures 1, 3c). In ad- the river mouth was built by the Corps to evaluate the problem. diti on, 10 rotar y auger borings were conducte d in 1994, identi fy- Farrell (1972) was the first to compile all the his tor ical ing bar rier, back-bar rier, and gla cial-marine fa cies and maps and aeria l photo graphs of the region’ s beaches. Nel son re triev ing sed i ments for anal y ses. Beach to pog ra phy was dig i - (1979) extende d this early work on shoreli ne change and graphi - tized from mylar flood insur ance rate maps which have a 0.66 m cally depict ed the histor i cal growth of Pine Point, at the northern con tour in ter val. Beach profiles were made seasonally at 5 end of the main cen tral beach sys tem in Saco Bay. Pine Point has stations following the Emery (1961) method. conti nu ously grown eastward and seaward since the 19th cen- Eval u a tion of off shore cur rent ve loc i ties and waves in- tury. Be tween 1877 and 1923 it grew 137 meter s (Farrell, 1972) volved use of an S4 electro m agneti c current meter and four partly in re sponse to clos ing of the Lit tle River in let to the south Endeco 105 im peller current meter s. Endeco 105 current meter s when a rail road line was built circa 1875. By 1955 the measured mean flow at 30 minute inter vals while the S4 evalu - Scarborough River inlet require d dredging for navi ga ti on, and in ated wave pe riod and height, and orbit al ve loci ti es, in short-term 1957 a jetty was construc ted at the southern side of the river en- burst sam pling, at 1 m over the bottom (Figures 1, 3a). Taut-wire trance. By this time the Scarborough River inlet had narrowed moorings were array ed with with Endeco meter s at 1 and 12 m from 762 to 207 m. above the seabed and on one deploy ment the S4 re placed the Dredg ing has oc curred in the Saco es tu ary since the early Endeco at the 1 m posi ti on. Four deploy ments, sum mariz ed in 19th century , in the Scarborough Es tuary since 1955, and in the Table 2, were com pleted in 1991 and 1992, two in a shelf valley entra nce to Biddeford Pool since 1956 (Normandeau Asso ci - in south-centra l Saco Bay, 1.7 km north-northeas t of Wood Is- ates, 1994). Sandy spoils have often been placed on nearby land, one in the center of Saco Bay, 3.5 km east-southeas t of the beaches, although occa sion all y dredged mate ria l has been dis- Old Orchard Beach pier, and one site 1 km southeas t of Prouts posed “in open water ” (Table 1). A recent review of dredging Neck. The Old Orchard Beach and Prouts Neck deployments within Saco Bay has chroni cle d the dredging history of the bay were concurrent. since 1950 (Normandeau Asso ci ate s, 1994), but dif fers in detai l In the Saco River, current veloc it y and direc ti on, tem pera - from older dredging studies (Mahoosuc Corp., 1982) and evalu - ture, and sa lin ity were measured us ing Marsh-McBirney and ati ons of shore line change (Farrell, 1972; Nelson, 1979). Teledyne Gur ley cur rent meters and YSI sa linom e ter . Read ings

6 A Sand Budget for Saco Bay, Maine

TABLE 1: DREDG ING HIST ORY OF SACO BAY

SCARBOROUGH RIVER ESTU ARYa SACO RIVER ES TU ARY (con tinued)

YEAR VOL UME DIS POSAL SITE COM MENTS 122 year total = 773,246 m3 DREDGED Av erage annual dredge volum e = 6,338 m3 3 (m ) Saco es tuary filling rate fol low ing last expan sion (10 yr) = 8,481 m3/yr 1956 97,906 open wa ter initial dredging ; most placed on beachb, c 1962 114,645 open wa ter PROJECTED FU TURE DREDGING 1965 24,899 open wa ter 1969 35,922 open wa ter TIME FRAME VOL UME DISPOSAL SITE 1973 144,300 open wa ter pos si bly up landc 1975 6,948 open wa ter possi b ly intertidalc 1995-2005 84,073a not de ter mined, prob a bly beach 19 year total= 424,620 m3 3 Av erage annual dredge volum e = 22,348 m 1995-2045 420,365a not de ter mined, prob a bly beach Scarborough estu ary fill ing rate fol low ing first dredge = 17,195 m3/yr

PROJECTED FU TURE DREDGING BIDDEFORD POOL TIME FRAME VOL UME DISPOSAL SITE

c c 1995 175,743 not de ter mined YEAR VOL UME DISPOSA L SITE COM MENTS 1995-2005 191,075a not de ter mined a DREDGED 1995-2045 898,052 not de ter mined (m3)

1956 57,177 open wa tera im provem ent

1956 2,707 up landa ini tial dredge SACO RIVER ES TU ARY 1971 287 up landa 1976 306 up landa 1979 382 up landa ini tial dredge YEAR VOL UME DIS POSAL SITE COM MENTS 1988 860 open wa tera DREDGED 1988 35,095 open wa tera dis posal site (m3) moni tore df 1989 12,233 beachf 1827 ??? ??? ini tial clear ing of a river, building of 1992 9,439 off shore im provem ent piers, buoys 33 year total = 118,486 m3 BY 1872 84,073 ??? Av erage annual dredge volum e = 3,590 m3 1886 12,515 ??? chan nel deep ened

to 1.8 m Biddeford Pool fill ing rate fol low ing last ex pan sion (10 yr) = 4,819 m3/yr 1912 65,279 ??? chan nel deep ened to 2.1 m 1919 “large quantity ” beach as sume min i mum PROJECTED FU TURE DREDGING 60,000 m3 1928 63,437 ??? chan nel deep ened TIME FRAME VOL UME DISPOSAL SITE to 2.5 m 1995-2020 25,232a not de ter mined 1939 60,824 ??? 1995-2045 50,464a not de ter mined 1940 48,151 ??? 1965 28,279a up land a 1969 66,765 beach ex panded an chor age a a (from Normandeau Asso ci ates , 1994; most val ues and 1969 55,893 beach dif fers from disposal sites dif fer from Mahoosuc Corp., 1982) Mahoosuc, 1982 b a (some or all of this filled in Pine Point, Farrell, 1972) 1973 28,279 nearshore c a (Mahoosuc Corp., 1982) 1978 61,144 beach dif fers from d (project ed by U.S. Army Corps of Engi neer s, 1994, personal Mahoosuc, 1982 a com mu nica tion) 1978 38,215 beach e a (per sonal com mu ni ca tion, Maine State De part ment of En vi ron men tal 1982 5,579 beach ex pan sion of Pro tection) an chor age f e (Maine Geo log i cal Sur vey) 1992 10,000 beach new an chor age 1992 65,706a beach 1992 19,107a in channel d

7 Kelley and others

Figure 3a: Lo cation of data collected for this re port. (a) Area of side-scan sonar swaths shown with ruled pattern, with bot tom sam ple lo ca tions lo cated as filled circles. The three black boxes locate current meter sites.

Figure 3(b): Lo ca tion of seis mic re - flection lines and vibracore sites (filled cir cles).

8 A Sand Budget for Saco Bay, Maine

Figure 3c: Lo ca tion of ground-pen e trat ing ra dar (GPR) lines and vibracore sites.

9 Kelley and others TA BLE 2: CUR RENT ME TER DE PLOY MENTS

LO CA TION LAT I TUDE LON GI TUDE WA TER DATES TYPE DEPTH Shelf Valley 43° 28.0’ N 70° 19.2’ W 30 m 8/2-9/18/91 Endeco 12 m Endeco 1 m Shelf Valley 43° 28.0’ N 70° 19.2’ W 30 m 3/5-3/20/92 Endeco 12 m S4 l m Cen tral Saco 43° 29.8’ N 70° 19.8’ W 22 m 7/15-8/18/92 Endeco 12 m Bay Endeco 1 m Prouts Neck 43° 30.9’ N 70° 17.9’ W 22 m 7/15-8/18/92 Endeco 12 m Endeco 1 m

NOTE: Mooring loca tions in Saco Bay are shown in Figure 3a.

were taken at three loca ti ons through the water colum n (1 m off tion of the map unit, which is re quired by the extre me het ero ge - the bot tom, mid-depth, and 1 m below the surface ) at 5-10 sta - neit y of the seafloor and the res olu ti on of the side-scan sonar . tions in the Saco es tuary over com plete tidal cycle s during spring Within the beach and dune areas, bedrock outcrops are limited in freshet, tide-dom inate d, and mean condi ti ons. In addi ti on to number as well as size. data gathered di rectly by this project , data on wind veloc it y and Rippled coarse sand and gravel covers 9% of the Saco Bay wave height from the Portland Large Navi ga ti on Buoy (LNB; R. in wa ter depths from 5 to 45 m (Figures 4, 5a, b). Four disti nct Ma rine, Na tional Weather ser vice, per sonal com mu ni ca tion), 11 lo cations of these coarse-grained rip ples (CGR) are iden tified. km to the east-north east of Saco Bay, were an alyzed. Stream Three lo ca tions con tain large os cil la tory rip ples with mean gauge data for the Saco River at Cornish, ME, were uti lized as wavelengt hs of 1.3 m and am pli tudes of 20 cm (sim ilar in size to well (Bartlet t and others, 1993; U.S. Geological Survey, those measured by Belknap and others, 1988). The finest mean personal communication). grain size from os cil la tory CGR sites was 1 phi (0.5 mm) (me- All data were transferred to a Geographic Infor mation Sys- dium-coarse sand), while the coars est sam ples con tained cob - tem (GIS)(ARC/INFO) for analy sis of sedi m ent vol umes and ar - bles (Bar ber, 1995). Exten sive fields of ripples lie gener all y chi val pur poses. His tor i cal ae rial pho to graphs were an a lyzed on south of Prouts Neck and Richm ond Island (Figures 4, 5b). an an a lyt i cal stereoplotter and his tor i cal shore line po si tions Elongate CGR ribbons range from 100 m to 250 m in width and were transferred to the GIS for analy sis (Dickson and Kelley, 0.5 km to 2.0 km in length. Some connect to larger bedform 1993). Ar eal and volu metric quanti ties quoted in this paper are fields while others oc cur in isolat ed, subparallel groups. A more based on GIS-computed values. restri cted occur rence for the rippled bot tom is adja cent to bed- rock out crops, or over loca ti ons where bedrock is buried by less than 5 m of sedi m ent (Figure 5a). Kelley and others (1989a) in- RESULTS ferred that in these lo cations ero sion of gla cial-marine sed im ent di rectly over ly ing rock, and car bon ate de tri tus from en crust ing Surficial Sed i ment or ganism s, provide coarse mate ria l from which the ripples form.

Bedrock is exposed over 8% of the bay, and crops out on the shallow , subm erged mar gins of all islands in the bay sea ward of the penin su las at Biddeford Pool and Prouts Neck. Bedrock is TA BLE 3: AR EAL EX TENT OF SEAFLOOR TYPES MAPPED IN exposed along the shore line in several places in Cape Eliza beth SACO BAY and in many small, isolat ed shoals scat tered throughout the bay % OF AREA (Table 3; Figure 4). Rock is most exten sive in the shallow wa ter BOT TOM TYPE AR EAL EX TENT MAPPED IN 2 near Bluff and Stratton Islands in the centra l bay, regions pre vi- (m ) FIGURE 4 ously include d as Rocky Zones on physio graphi c maps (Kelley and others, 1987; 1989a; 1989b). All outcrops of bedrock con- Bed rock 12,100,00 8.0 tain some coarse-grained talus and carbon ate sedi m ent filling in Mixed rock and gravel 45,700,000 30.5 Gravel (smooth) 4,600,000 3.0 large cracks (Nep tu nian dikes), and most rocky ar eas are closely Coarse sand and gravel (rippled) 13,900,000 9.3 asso ci ate d with mixed rock and gravel, and gravel depos it s (Fig - Medium and fine sand 25,100,000 16.8 ures 4, 5a; Kelley and others, 1989a). Mixed rock and gravel, oc- Muddy sand 25,000,000 16.7 cupy ing 30% of the bay bot tom, is the most com mon seafloor Sandy mud 18,500,000 12.3 Mud 5,100,000 3.4 envi ron m ent; it increa ses in abundance offshore. One reason for the unusual abundance of this seafloor type is the broad defi ni - NOTE: Geographi c distri bution of these bottom types is shown in Figure 4.

10 A Sand Budget for Saco Bay, Maine

Figure 4: Surficial sed i ment map based on the side-scan sonar and bot tom sample ob ser va tions. The muddy sand also in cludes sandy mud and the rip pled gravel also con tains coarse sand.

Di rect ob ser va tions from a sub mers ible con firm the pres ence of offshore into muddy sand in most places by the 20 m isobath. carbon ate -rich, coarse clastic halos around bedrock out crops Muddy sand covers the previ ously mapped Shelf Valley s which (Belknap and others, 1988). A final loca ti on with a rippled slope gently offshore into the deeper Gulf of Maine (Kelley and seafloor is locat ed within the estu ary of the Saco River where others, 1989a). At about the 40 m isobath, muddy sand within strong tidal currents produce unidirectional megaripples the Shelf Valley s grades into sandy mud which, in turn, grades to (discussed below). mud around 65 m depth (Kelley and others, 1987). Seism ic re- Medium to fine sand occurs in water depths less than 15 m cords show that the large area of muddy sand mapped be tween direct ly offshore of many beaches of the region (Figure 4). This Prouts Neck and Cape Eliz abeth (Fig ure 4) de lin eates an area shoreface area is large (17% of the bay, Table 3) and rel atively where till and glacia l-marine sedi m ent crop out on the seafloor. feature less except where broken up by rock out crops. A north- Many large (1 m) boulders rest on the surficial mud of the area ward fining trend in grain size of offshore sedi m ent be tween 5 and may be a lag deposit (Kelley and others, 1989a). Although and 7 m depth paral lel s a sim ilar trend observe d onshore by occu py ing more than 30% of the bay, littl e analysis was made of Farrell (1972; Figure 6). Medium to fine sand nearshore grades muddy areas for this project.

11 Kelley and others . p o r c t u o

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12 A Sand Budget for Saco Bay, Maine . 1

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13 Kelley and others

Figure 6: Trends in grain size along the shoreface and intertidal beach from Camp Ellis to Pine Point (mod i fied from Bar ber, 1995).

Shal low Stra tig ra phy and Off shore Sand Vol ume cial-marine mud to fine sand at 3 m depth in core VCSC92-02. Above the uncon form ity the basal sand becom es muddy (32% Shore-nor mal seis mic re flec tion pro files re veal an ir reg u - sand, with a range of 9 to 48%; Barber , 1995) Ra diocar bon dates lar bed rock base ment over lain by a rel atively thick, acous tically on woody mate ria l (6,110 æ 50 yr B.P.) depos it ed with salt marsh trans par ent unit in ter preted as gla cial-ma rine sed i ment (Fig ure foraminifera (Trochammina inflata), and an ar ticu lated mol lusc 7). The surface of this unit is marked by a rel ati vely strong (Macoma balthica; 7,060 æ 35 yr B.P.) estab li sh a mid-Holo cene , acous tic refle ctor which dips very gently seaward (1:275, Figure estuarine set ting (He). The stratigrap hic re ver sal of the radio car - 7) and is cut by appar ent channels in a few places. Overly ing the bon dates (Figure 8) is best explai ned by rework ing and later de- strong re flector is a wedge that only local ly can be resolve d into posi ti on of the older Macoma shell. The sedi m ent be comes more than one unit. This wedge begins at 20 m water depth and sandier toward the top of the core (Hs), but Crassostrea frag- thickens to approximately 10 m at the shoreline. ments sug gest mainte nance of the estuarine (back-bar rier?) en - Vibracores pene tra ted each of the uncon sol i date d units viron m ent unti l about 55 cm in the core. Here an abrupt increa se and con firmed the pres ence of gla cial-marine mate rial (Pgm) at and coarsen ing in the sand content occurs and marks the appar - depth as was previ ously recog nize d in other cores from the area ent ravinement uncon form ity (Figure 8). A shell hori zon at 15 - (Kelley and others, 1990, 1992) (Figure 8). Holo cene sedi m ent 20 cm, com monly seen on many other cores about this depth, un con form ably over lies the Pleis to cene ma te rial and the strong proba bly repre sent s a storm deposit (Davidson-Arnott and acous tic reflec tor cor re lates well with the change from gla- Greenwood, 1976; Hunter and others, 1979; Barber, 1995).

14 A Sand Budget for Saco Bay, Maine

Figure 7: Orig i nal (top) and inter preted (bot tom) seismic re flec tion pro file (SRP) 9132 from the Old Or - chard Beach shoreface. Seismic line lo ca tion is shown in Fig ure 1. Vibracore 9202 is de picted in Figure 8. Units are as fol lows: Hs - Holo cene sand; He - Holo cene estuarine sed i ment; Pgm - Presumpscot Forma - tion, gla cial-ma rine sed i ment; br - bed rock. VE is vertical exaggeration.

The other shore-norm al seis mic profil es de pict a Anom alousl y thick accu m ula ti ons of sand (>5 m) occur in two wedge-shaped body of Holo cene sand extend ing out to the 15 - elli psoi dal bodies , one at the mouth of the Saco River jet ties, and 20 m depth (Barber , 1995), where muddy surficial sedi m ent the other paral lel to the river one ki lom eter north. Another un - marks the out crop of glacial-m arine mate rial on the seafloor usuall y thick de posit of sand (7 m) occurs south of Pine Point, (Fig ure 4). There are sev eral ex cep tions to the gen er alized where the shoreface ex tends far ther sea ward than else where in wedge-shape of the Holo cene shoreface sand body (Figure 9a). the bay. In loca ti ons with shal low bedrock, thinner depos it s ex-

15 Kelley and others

Figure 8: Log of vibracore 9202. Wa ter depth = 14.1 m (MHW datum). Seismic line over core site is shown in Fig ure 7. ist, with the excep ti on of a J-shaped accumulation over 1 m thick The barrie r and back-barrie r sedi m ents are subdi vided into in the central bay. three units on the basis of morphologic, vibracore, and GPR data On the basis of side-scan so nar images, seis mic re cords and (van Heteren and others, 1996; Figure 10a). The sandy lower cores, the Holo cene wedge of sedi m ent was esti mated using the barrie r unit forms a discon ti nu ous buried beach ridge that ex- GIS to oc cupy a volum e of 6.63 x 107 m3 (Figure 9a). After sub - tends from the Saco River entra nce to Goosefare Brook, along tracting the aver age mud content of the cores from this volum e, the southern part of Saco Bay. Back-barrie r depos it s of muddy the best es tim ate of clean Ho lo cene sand in the shoreface is ap - fine sands were identi fied. Also present along the southern part proxi m ately 5.62 x 107 m3. of the bay are elongate d ponds, which occupy sites of form er back-barrie r la goons. These relict lagoons and asso ci ate d salt Shal low Stra tig ra phy and On shore Sand Vol ume marshes and tidal flats formed behind the middle barrie r unit as spits accreted northward from several bedrock pinna cle s and Ground-pene tra ting ra dar (GPR) profil es re veal a com plex other ele vate d anchor points. Local ly, parts of this system are bar rier and back-bar rier stra tig ra phy on a base of gla cial-marine now buried, but south of Goosefare Brook, recurves of two gen - muds (Presumpscot Form ati on; Figure 10). Bedrock was found era ti ons of paleospits extend into the modern salt marsh be hind in approx i m ately 10 loca ti ons by the GPR. Northwest of the barrie r (Figure 11; Farrel, 1972; Nelson, 1979; Kelley and Goosefare Brook the basal strata im aged by ra dar are formed by others, 1989a; Millette, 1993, 1997). Both northerl y and sea - glacia l-deltaic sands that were depos it ed during the late ward spit ac cre tion are ob served in the sigmoidal re flec tors seen Wisconsinan ice re treat, circa 14 to13 ka. These sands may have in GPR records in the northern porti ons of Old Orchard Beach, extende d into the present bay, and, as such, may have formed a parti cu lar ly at Pine Point. The back-barrie r region behind this source of some of the sand now present in the barrie r sys tem (van sec tion of the barrie r has alway s had an open connec ti on to Saco Heteren and others, 1994a). Bay at the Scarborough River in let. No sep arate early

16 A Sand Budget for Saco Bay, Maine

Figure 9. Ho lo cene sed i ment isopach (thick ness) maps: (a) isopach map of Ho lo cene sed i ment along the shoreface (from Bar ber, 1995). (b) Ho lo cene sand isopach map for the beach, dunes and back-bar rier re gions of Saco Bay (from van Heteren, 1996). Pat terns rep re sent thick ness of sedi ment be tween con tour lines. Shoreface thick ness ex ceeds 7m near Pine Point and dunes are over 9m thick in some locations. paleolagoon was identi fied, as in southern secti ons. The present The com bined data for the Saco embayment suggest that barrie r repre sent s, for the most part, a net seaward widen ing of the shoreli ne evolved through repeat ed, but not nec essar il y syn - the mid dle bar rier unit (the spit sys tem) at a later time. At Pine chro nous, land ward and along shore (pri mar ily north ward) Point there has been signif i cant lonsgshore spit accretion as part movem ent of the sandy barrie r. This sedi m enta ti on history and of the development of the upper barrier unit (Figure 10b). morphologic de vel op ment prob a bly re sulted from changes in GPR re cords, rotar y au ger and core data from north of Old the bal ance be tween the rates of rel ative sea-level rise and sed i- Or chard Beach demon strate that back-bar rier peat and clastic fa - ment supply (van Heteren and others, 1996; van Heteren, 1996). cies have infilled low-ly ing Pleis tocene paleotopography. The On the basis of the regional topog ra phy , GPR records, back-barrie r depos it s, in turn, are overlai n by, and interfinger vibracores, and rotar y-auger drill ing, we used the GIS to esti - with, washover and eolian barrie r facie s (Figure 10c). mate that 2.2 x 107 m3 of sand exist s in the dune, beach and other High-marsh peat from beneat h the centra l porti on of the barrie r barrie r depos it s (Figure 9b; van Heteren and others, 1994a). The just north of Old Orchard Beach yields a radio car bon age of gen er ally muddy and spatially more restricted back-bar rier de - 2,850 æ 75 yr B.P.. This date constra ins the age of this porti on of posit s were not include d in this calculation. the barrie r as it transgress ed its own back-barrie r depos it s. The Include d in the calcu la ti ons are wedges of sand that extend pres ence of peat un der neath the bar rier lithosome im plies a com- both landward into the salt marsh (washover and tidal inlet s fa- ponent of onshore migra ti on of the barrie r during this stage of cies) and sea ward to a the o ret ical depth at which the en tire bar - devel op m ent, and not exclusively longshore accretion of a spit. rier lithosome has been eroded at the ravinement sur face. The

17 Kelley and others

Figure 10. Ground-pen e trat ing ra dar (GPR) data from Saco Bay beaches. Lo ca tions are shown in Fig ure 1. (a) Inter preted and origi nal GPR record across the back barrier and part of the barrier beach near Ferry Beach State Park (from van Heteren and oth ers, 1994b).

Figure 10(b): Orig i nal GPR re cord from Pine Point showing clinoform re flec tors dip ping to wards the Scarborough River es tu ary.

18 A Sand Budget for Saco Bay, Maine

most prom inent area of sand ac cum ula ti on within the litto ral sys - tem is Pine Point. Here a 500 m wide and 2 km long sand body has an aver age thickness of 6 m and reaches a maxi m um of 9 m. Elsewhere, sand de posit s betwee n 6 and 11 m in thickness oc cur in an elongate 100 m wide belt that extends alm ost conti nu ously betwee n the Saco and Scarborough Rivers. The belt coin cide s with the area of highest dunes. Lesser quanti ties of sand are found in areas with ele vate d bedrock or in dune areas disturbed by human development.

Dy namic Estuarine Re gime

The lower Saco River (10 km) is cut into bedrock at vari ous lo ca tions, and its mor phol ogy is char ac ter ized by rel a tively deep gorges (5 - 8 m) sepa rat ed by wide, shal low reaches (2 - 4 m) bor- dered by marshes and tidal flats (Figure 12; Kelley and others, 1994b). Most of the river is floored by medium to coarse sand except in gorges, where cobbles and boulders pre dom inate (Manthorp and others, 1994; Manthorp, 1995). Bot tom sam ples, hy dro graphic mea sure ments, and side-scan so nar ob ser va tions in di cate that two dis tinct re gimes exist in the Saco River es tuary . During norm al river stages, which encom pass most of the year, the estu ary is highly strati fie d with well-de fined thermoclines and haloclines (Figure 13). Un- der these condi ti ons the upper two-thirds of the estu ary is dom i- Figure 10c: Log of ro tary au ger core SB94-RA9.

Figure 11: Paleospits in the Goosefare salt marsh are vis i ble in this 1991 ae rial pho to graph. Two gen er a tions of spits ap pear to ex ist, with the earlier attached to a former seacliff and the later spit at and beneath the present barrier. Some of the latter’s subsurface fea- tures were im aged in Fig ure 10a. (mod i fied from Kelley and oth ers, 1989a)

19 Kelley and others

nated by ebb flow with stronger aver age and bottom current s (by 3 to 63 cm/sec; Figure 13). The lower porti on of the estu ary ex- pe ri ences dom i nant av er age ebb flows; how ever, bot tom cur- rents exhibi t stronger flood veloc i ti es (4 to 16 cm/sec; Figure 14a). Bedforms are re stricted to thalweg re gions and reflect distinct areas of flood and ebb dominance. During spring freshets, the freshwa ter dischar ge, which in- creases by more than an order of magni tude (Barber , 1995), sup- plants the salt wa ter tidal prism, re sult ing in to tal domi na tion of the estu ary by riverine proces ses (Manthorp and others, 1994; Figure 13). Flow is in an ebb di recti on at all stages of the tide and at all depths. This condi ti on may persis t for several weeks. Dur- ing this pe riod, medium to coarse-grained sands floor much of the estu ary and ebb-ori ented bedforms occupy more than 50% of the channel bed out to the seaward end of the jetties (Figure 14b). No com plete sand dischar ge records exist for the Saco River, but tem poral ly lim ited data exist on the suspended sand content at a gauging stati on 35 km above the head of tide (Bar- ber, 1995; Bart lett and others, 1975-93). Re gression of the sus- pended sand volum es, from the lim ited times of obser va ti on to all stages of river dischar ge, yields an esti mate of 6,100 m3/yr of sand dischar ged by the river. This is a mini m um esti mate since the bedload discharge was not evaluated.

Dy namic Beach Re gime

Geomorphological and GPR ob ser va tions dem on strate that during the latest Holo cene , sand travele d from south to north in Saco Bay (Figures 10, 11). The orien ta ti on of paleospits (Kelley and others, 1989a) and their conti nuit y (van Heteren and others, 1994a, 1996) along the southern part of the beach are in - dica ti ve of an im portant quanti ty of sand de rived from the Saco River. GPR obser va ti ons at Pine Point also depict the northeas t- ward growth of that spit into the Scarborough River Inlet (Figure 10b; van Heteren and others, 1994a, 1996; van Heteren, 1996). Fining grain sizes from south to north along both the beach and nearshore are also sugges ti ve of net northerl y transport (Figure 6; Farrell, 1972). His tor i cal mea sure ments of shore line po si tions also doc u- ment a conti nu ing movem ent of sand from south to north. Charts depict a very large ebb-tidal delta at the mouth of the Saco River in 1866 (Figure 15a). This sand body was de stroyed by con- struc tion of the north jetty, and sand moved ashore (Farrell, 1972). After 1896 the beach and nearshore area north of the jetty under went erosion. Bathymetric changes betwee n high wa ter and the 5.5 m isobath from 1859 to 1955 indi cat e loss of 5.95 x 106 m3 of sand in the southern part of the bay (USACOE, 1955). The Lit tle River inlet closed betwee n 1871 and 1877, proba bly in Figure 12: Bathymetry of the Saco River Es tu ary and lo ca tion of Fig - response to the northward movem ent of that sand (Farrell, 1972; ures 13 and 14. Bathymetric data from NOAA chart 13287. Figure 15b). The si multa neous northward growth of Pine Point require d at least 1.36 x 106 m3 of sand moving from the south. Even more sand lies off of Pine Point in the ac tive ebb- and

20 A Sand Budget for Saco Bay, Maine

Figure 13: Hy dro graphic data from the Saco River Estu ary dur ing spring and summer (from FitzGer ald and oth ers, 1993, and Manthorp, 1995).

flood-tidal deltas of the Scarborough River inlet and the flood tion 40 - 80 meter s. Com pari son of 1976 and 1991 beach pro- tidal delta of the abandoned Little River inlet (Figure 16). files suggest s that this erosion and progradation is conti nu ing Com pari son of ae rial photo graphs from the past 40 years (Figures 17b; 18). At Camp Ellis the beach erosion led to con - docu m ent the conti nued erosion of the beach near the north jetty struc tion of sea walls by 1953 (USACOE, 1955) in an attem pt to at Camp Ellis (Figure 17a) and the conti nued ac creti on of the reduce the loss of propert y. As a re sult, the rate of landward re- beach at Pine Point (Figure 18a). At Pine Point, the spit has treat has abated somewhat from earlier val ues. Since then grown southeas tward towards Prouts Neck in a sea ward di rec- unarmored shore lines have retreated 10 - 30 m (Figure 17a).

21 Kelley and others . 1 9 9 1

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23 Kelley and others

Figure 15(a). The shore line and nearshore bathymetry of the Saco River mouth in 1866 (USACOE, 1955).

Figure 15(b): The shore line and nearshore bathymetry near Pine Point be tween 1859 and 1871 (USACOE, 1955).

24 A Sand Budget for Saco Bay, Maine

Figure 16: In ferred bathymetric changes re sult ing from the con struc tion of the north jetty at the Saco River mouth. Bathymetry near the Saco River was eval u ated by the U.S. Army Corps of En gi neers (1955); bathymetric changes at the Scarborough River mouth are pro jected on the ba sis of ex ist ing bathymetry and the known vol ume of mate rial added to Pine Point and lost from Camp Ellis. Check - ered pat tern shows area of new beach added to Pine Point.

great est speeds in the el lipse were into and out of Saco Bay Dy namic Off shore Re gime (northwest -southeas t) along the axis of the shelf val ley, but never strong enough to transport sand and gravel (Dickson and Current meter s, deploy ed at 1 and 12 m above the bottom in others, 1993a, b). 20 - 30 m water depth, measured mean current s (Pugh, 1987), High fre quency (4 - 5 sec), revers ing wave-orbit al current s tidal current s, wave orbit al moti on, and wind-driven cir cula ti on capa ble of entra ining sand and gravel were observe d on several (Table 2; Fig ure 3a). Fair-weather tidal cur rents had speeds less oc casions. Or bital cur rents up to 48 cm/sec were measured be - than 15 cm/sec and were rotar y, result ing in a tidal elli pse. The neath 2 m storm waves with a period of 10 seconds during a

25 Kelley and others

Figure 17: Shore line change at Camp Ellis, 1953-1991. (b) Beach pro file com par ing el e va tions from 1976 to 1991. Pro file lo ca tion shown in (a) above (L. K. Fink, writ ten com muni ca tion, 1992).

26 A Sand Budget for Saco Bay, Maine

Figure 18: (a) Shore line change at Pine Point, 1953-1991. (b) Beach pro file com par ing el e va tions from 1976 to 1991. Pro file lo ca - tion shown in (a) above (L. K. Fink, writ ten com muni ca tion, 1992).

March 19, 1992 northeas ter (Dickson and others, 1993a). Al- the coast line. Then, a re versal of the wind di recti on led to 24 though these current s were fast enough to transport the shoreface hours of onshore (northwest ) bottom flow, overwhel m ing the sand, their re vers ing di rec tions (north west-south east, or on - ebb-tidal current of August 20. The offshore current s reached 30 shore-offshore) proba bly led to little net sand movement. cm/s, while the onshore current s ranged from 15 - 20 cm/s. The Wind-driven circu la ti on was also observe d to gener ate cur- dura ti on of upwelling was approx i m ately twice as long as the rents ca pable of moving sand. A northeas t storm on August 4 - 5, downwelling, and per sisted about half a day after the winds had 1991 create d an offshore-di rected bottom current of 20-35 slack ened. Sig nif i cantly, no beach ero sion ac com pa nied the cm/sec for up to 12 hours (Dickson and others, 1993a). This hur ri cane, rather, Old Or chard Beach accreted sediment proba bly result ed from an onshore wind-driven surface current (Dickson and others, 1993b). that induced a coastal set-up leading to the offshore-di rected, downwelling storm current. DISCUSSION Sim i lar con di tions were ini tially pro duced on Au gust 19-21, 1991 when Hurri cane Bob tracked across Saco Bay (Fig- Ori gin and Direc tion of Movement of Saco Bay Sand ure 19). The approach of the storm, with onshore-di rected winds, produced a downwelling, offshore-di rected flow at 12 m The Army inferred that an eroding glacia l deposit in Saco above the bottom for 12 hours unti l the eye of the storm crossed Bay suppli ed local beaches with sand (USACOE, 1955). Once

27 Kelley and others

Figure 19: Wind ve loc ity, cur rent ve loc ity, and at mospheric pres sure pre ced ing, dur ing, and fol lowing Hur ri cane Bob (from Dick - son, in prep.). Dashed wind vec tors rep re sent gusts.

28 A Sand Budget for Saco Bay, Maine eroded on the seafloor, they be lieved that the sand moved land - the Camp Ellis anchor age of 6,300 m3/yr or of the modern ward to a nodal point near Old Orchard Beach and then travele d infil ling rate of 8,500 m3/yr (Ta ble 1). The in fill ing rates are also north to Pine Point and south to Camp Ellis. The north jetty at the mini m um esti mates of the sand intro duc ti on to the bay from the mouth of the Saco River was construc ted to inter cept the inferred Saco River becaus e an unm easured vol ume of sand leaves the north-to-south movem ent of sand in the lit toral drift (USACOE, river mouth and enter s the bay during freshets. We as sume that 1910, 1955). the intertidal de posit s of the Saco estu ary are in equilibrium or Sup port for this hy poth e sis in cludes the ori en ta tion of a are accumulating sand at very slow rates. small modern spit on the northern side of Goosefare Brook, indi - Paleospit ori en ta tion sug gests south-to-north lit to ral sand cat ing southerl y sand transport. In addi ti on, hindcast mete o ro - movem ent (Figure 11), which is also indi cat ed by GPR re cords logi cal and oceano graphi c data (Jensen, 1983) indi cat e that the (Figure 10; Farrell, 1972; Kelley and others, 1989a; van Heteren north east-east is the di rec tion from which the largest storm wind and others, 1996). The small, south-oriente d spit at Goosefare and waves approach the outer bay during the winter . The Army Brook is paired with a north-ori ented spit on the other side of the assum ed that the more com mon sum mer waves, which are de- in let and is an ar tifact of lo cal wave re frac tion. A strong ar gu - rived from the southeas t-southwest , are too small to be im portant ment for net northward sand movem ent is in the his tori cal obser - rel ati ve to winter storm waves, and that they are blocked by vati ons of Pine Point’s growth and Camp Ellis’ concur rent Biddeford Pool and by the north jetty. The Army cites recent erosion. Alm ost 6 x 106 m3 of sand left the river mouth area in the shoal ing adja cent to the north jetty as evi dence for north to south century follow ing construc tion of the north jetty (USACOE, litto ral sand transport, and the succes s of the north jetty in pro- 1955). At the same time 1.3 x 106 m3 of sand was added to the tecting the navi ga ti on channel from filling. Fi nally, unfil led de - subaerial beach and dunes at Pine Point. If the region offshore of pressions in the Saco es tuary and dams on the Saco River have Pine Point, which today repre sent s the largest single de posit of been cited as ev idence for a lack of con tem po rary river sand in Saco Bay, accreted only 0.5-1.0 m verti cally during that contribution to the bay (Maine State Planning Office, 1979). same time, it would account for an addi ti onal 3.5 x 106 m3 of Our surficial sedi m ent obser va ti ons in Saco Bay contra dict sand. Ad di tional sand ex ists in the rel ict flood-tidal del tas of the the early, unsup porte d assum pti ons of the Army that there is a Lit tle River (Figure 15) and Scarborough River (Farrell, 1972). signif i cant source of gla cial sand in the bay. Most of the sand in Thus, to account for the sand lost near Camp Ellis, it is nec essary the bay is part of the shoreface profil e of equi librium (Figure 4) for a sig nif icant net north erly lit to ral trans port to ex ist. The con - and so cannot provide new sand to the shoaling Saco River chan - tinu ing build-out of Pine Point and erosion of Camp Ellis sug - nel or to the beaches. Muddy or rocky mate ria l crops out over gests this is an ongo ing proces s (Figures 17, 18). During the last most of the rem ainder of the bay (Table 3; Figure 4). A lag de - dredging of the Camp Ellis anchor age (1992), the 65,000 m3 of posit near Prouts Neck proba bly repre sent s a re worked till or sand intro duced to the beach quickly disap peare d, and woody, gla cial-marine de posit that may once have been impor tant as a shelly estuarine sand blocked Goosefare Brook and was ob - source of sand and gravel. Side-scan sonar records provide evi - served all along the rem ainder of the beach system (Figure 20) dence of wave and current rework ing of some of this offshore for months after spoils disposal (L. Mitchell, Saco City sea bed (Kelley and others, 1989a; Dickson and others, 1993a; Administrator, personal communication, 1992). Figure 5b), but the poten ti al source area for sand is small (4 km2) Off shore sands of Saco Bay are affected by com bined (Figure 4). An unrea son able and unob serve d amount of erosion flows gener ate d by storms. Exact ly how much volum e is trans- would be require d to produce the volum e of sand added just to ported from the beach offshore or from the offshore to the beach Pine Point in this century . Further more, the offshore sedi m ents is dif ficult to quanti fy. However , direc ti ons of movem ent can be are largely mud at depth (Kelley and others, 1992) and covered in ferred from cur rent meter data. Cur rents cre ated from waves, with only a veneer of coarse sedi m ent. Sand at nearby Pine tides and wind shear all com bine to produce speeds suf ficie nt to Point, by contrast, is fine-grained (Figure 6; Farrell, 1972; transport sand. Time-aver aged flows are deter mined prim aril y Barber, 1995). by tidal stage and wind direc ti on. Under rough seas these aver - Cur rent me ter ob ser va tions clearly in di cate that the Saco age flows can indi cat e the direc ti on of sedi m ent transport. For River is ca pable of transport ing sand downstre am of the dams exam ple, northeas terl y winds and an ebbing tide were found to from the head of tide at all times of the year, and that all sed im ent gen er ate off shore-di rected bot tom cur rents. These cur rents transport is ebb-ori ented during times of high dischar ge (Figure should transport sand away from the toe of the beach to the lower 13). Bedform anal ysis by side-scan sonar depict s offshore-ori - shoreface. Sand loss is parti cu lar ly likely to occur from the ented megaripples at the jetty mouth and im ply offshore sand beach to the shelf valley at the southern part of the bay and onto transport during the spring freshet (Figure 14). Sus pended sand muddier offshore sedi m ent. Sand enter ing the val ley may be transport upstre am of the dams suggest s that at least 6,100 m3/yr top o graph i cally con tained there, or in cor po rated into more co- of sand moves through the base-draining dams at the head of tide hesive muddy sedi m ents, and thus not easil y re worked back on - (Bar ber, 1995). This mini m um esti mate exclude s bedload trans- shore. In the shallow shoreface, on the other hand, condi ti ons port, but is only slightly less than the his tor ical in fill ing rate at are com monly condu cive to onshore transport of sand. It was

29 Kelley and others o c a S

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30 A Sand Budget for Saco Bay, Maine

Fig ure 21: Sand path ways in Saco Bay. seen that not all storm condi ti ons lead to offshore transport. In A Sand Budget for Saco Bay: 7,000 yr B.P. to 130 yr B.P. the case of Hur ri cane Bob, cur rent meter data sug gest that strong northwest erly winds and a flooding tide com bined to cause cur- The largest deposit of sand in the bay, 5.6 x 107 m3, re sides rents that transporte d sand onto Old Orchard Beach. Seism ic in the shoreface and ebb-tidal deltas (Figure 9). The second larg - profil es and cores dem onstra te that there is a seaward thinning est body of sand, 2.2 x 107 m3, is in the berm and dunes, includ ing wedge of shallow shoreface sands, and vir tuall y no sand below old washover de posit s (Figure 9). Al though we have not mea- about 16 m water depth. At present we cannot rule out offshore sured the volum e of sand in the es tuar ies , we as sume that such a transport into the shelf valley , but there appears to be a rel ati vely volum e is small rel ati ve to beach and offshore vol umes be cause: ef fi cient re cy cling of sed i ment on shore to the lit to ral sys tem. In (1) the Saco es tu ary pos sesses very lit tle ac com mo da tion space short, the offshore current s are vari able and influ ence d by for sand, and (2) the Scarborough estu ary is generally muddy meterological and oceano graphi c condi ti ons. The current s may (Farrell, 1972). in turn rework beach sands offshore at some times and offshore The rate of intro duc ti on of sand to the system from the Saco sands onto the beach at other times. The cumulative effect of this River today is proba bly greater than ei ther the value esti mated on variability is best observed in the geologic and historic record of the ba sis of the upstre am sand dischar ge of the river (6,100 evolution of the coast. m3/yr) or the value based on the infil ling rate of the anchor age

31 Kelley and others

(6,000-8,500 m3/yr; Table 1) because: (1) the dis charge value in - bay’s beaches betwee n 4,900 and 7,800 yr B.P. and the pres ent volves only suspended sand; and (2) the infil ling value neglec ts include s (1) radio car bon dates on back-barrie r fauna collec ted in sand passing through the jetti es into the bay. This latter obser va - offshore cores range from about 6 - 7 ka (Figure 8); (2) recent re- tion is further supporte d by the infil ling rate of nearby Biddeford construc tions that dem onstra te that the Wells barrie r beaches (25 Pool (3,600 - 4,800 m3/yr; Table 1), which proba bly derive s its km to the south) formed within that inter val (Kelley and others, sedi m ent from the Saco River as well. On the basis of this con- 1995), and (3) a slowdown in the regional rate of rel ati ve sider ati on, and consid er ing the infil ling rate of the Scarborough sea-level rise that occurred at that time (Barnhardt and others, River anchor age (17,000 m3/yr; Table 1) we have se lected 1995). 10,000 m3/yr to 16,000 m3/yr as a range within which the current An im portant com ponent of the progradation of the overall value proba bly falls (Figure 22a). The pre histori c sand dischar ge beach sys tem has been the growth of sand dunes. Cores and au - rate of the Saco River, as suming a con stant clim ate, was prob a- ger holes indi cat e that the eolian mate ria l ranges from 2 m to 4 m bly closer to the larger end of this range because some sand may in thick ness. Neglect ing the recently added mate rial at Pine be trapped behind dams. Point (Figure 18), the volum e of dune sand ranges from 4.0 to 8.0 The only possi ble offshore source of sand is locat ed south x 106 m3. If this deposit formed within 7,800 to 4,875 years, the of Prouts Neck and is today covered with rippled coarse sand and rate of eolian de posi ti on ranged from 500 m3/yr (2 m thick dunes gravel (Figure 4). That region, under lai n by both till and gla - form ing in 7,800 years) to 1,600 m3/yr (4 m thick dunes form ing cial-marine sedi m ent (Kelley and others, 1989a) and covered by in 4,900 years). Our best es ti mate lies in the middle of this range, ripples (Figures 4, 5b) oc cupies about 4 km2. All cores here con - around 1,000 m3/yr (Figure 22a). It is likely that dunes formed tain coarse-grained sed im ent at the top, with finer mate rial at quickly, and have been ef ficie ntly re cycle d throughout the late depth (Kelley and others, 1990; Luepke and Grosz, 1986). The Holocene. aver age sand content of the only core ana ly zed is 58%, which is a rel ati vely high value for glacigenic sedi m ent in Maine (approx i - mately 33 %, W. Thompson, personal com muni ca ti on, 1995; A Sand Budget for Saco Bay: 1859 to 1955 Kelley, 1989). If this area were origi nall y 5 m above present sea level (somewhat higher than nearby Bluff and Stratton Islands ) Dur ing the time in ter val 1859-1955, hu man ac tiv i ties and eroded to its present aver age depth of 20 m, it could account caused im portant changes in the loca ti on of sand storage within for al most 3.3 to 6.0 x 107 m3 of sand (assum ing a sand content of Saco Bay. The rate of sand intro duc ti on from the Saco River av- 33% and 58%, respec tively). A contri buti on of this magni tude is eraged from 10,000 to 16,000 m3/yr, but the construc tion of the un likely, how ever, be cause the sand in this area is coarse grained north jetty at the mouth of the river caused 61,200 m3/yr of sand (modal size of 2.8 phi; Kelley and others, 1990), and all the to move away from the Camp Ellis area (USACOE, 1955) to- nearshore sand is finer grained (3.2 phi; Figure 6). As this de- wards Pine Point (Figure 22b). This rate of hum an-induced, net posit eroded it would have quickly been capped by a lag deposit sand movem ent excee ded the long-term, nat ural rate of transport preserv ing deeper parts of the unit as observe d elsewhere by at least a fac tor of four. We as sume that this sand trav eled with (Forbes and others, 1991; Stea and others, 1994). Since there is wave-gen er ated long shore cur rents un til reach ing Pine Point. no evi dence of a more exten sive lag de posit, it is reason able to Al ter na tively, a lon ger-term pro cess of on shore-off shore sea - conclude that 10 m or less of erosion oc curred in this area. Ero- sonal cycle s of sand movem ent coupled with slow northward sion of a deposit of the present area and texture (33 - 58%) to 10 drift could have caused this transfer of sediment. m depth would yield 1.3 x 106 m3 to 2.3 x 106 m3 of sand. Ow ing By 1957, Pine Point had expanded 550 m from its to the proxim ity of Scarborough Beach to the northeas t of the long-term posi ti on (Farrell, 1972) and gained 1.4 x 106 m3 of area of rippled coarse sand and gravel, and the southern di recti on sand. Of this, be tween 1.0 and 2.0 x 105 m3 were added to sand from which the prevail ing sum mer winds origi nate , at least 50% dunes from 1859-1991, assum ing 2 or 4 m aggradation, respec - of this sand proba bly went to the Scarborough Beach sys tem. tively. This yields rates of dune growth be tween 840 and 1,690 This leaves only 0.65 - 1.15 x 106 m3 of sand to contri bute to the m3/yr, somewhat greater than the long-term aver age of the Old Orchard Beach sys tem. The im portanc e of this source of beach. Prob ably this is be cause of the finer sand size in the area sand has proba bly decreased with time as the lag deposit on the and much wider spit, upon which the dunes at Pine Point devel - surface thickened and its depth and distance offshore increased. oped, com pared with the rem ainder of the beach system. At the rate of sand intro duc ti on esti mated for the Saco Elsewhere in the bay during this time inter val, houses and River, 10,000 m3/yr to 16,000 m3/yr, the 7.8 x 107 m3 of sand in com mercia l es tabli shm ents were built on most of the sand dunes the enti re beach system would be deli vered in betwee n 7,800 and of the beach sys tem. Sea walls were later con structed along the 4,900 years (Figure 22a). Offshore sand, which might have been outer edge of most of the frontal sand dunes of the beaches, in - local ly im portant earli er in the bay’s his tory, would not af fect hibit ing or elim inat ing the exchange of sand be tween the beach these val ues by more than a few hundred years becaus e of the and dunes. small quan tity of ma te rial avail able from that source. Fur ther ev - We es tim ate that 3.5 x 106 m3 of sand accu m ulat ed offshore idence support ing the scenari o that the Saco River formed the of Pine Point, shoal ing that area by 0.5 to 1.0 m, and that the re-

32 A Sand Budget for Saco Bay, Maine

Fig ure 22(a): Sand bud get for Saco Bay from 7,000 yr B.P. to 130 yr B.P.

33 Kelley and others

Figure 22(c): Sand bud get for Saco Bay from 1859-1955.

34 A Sand Budget for Saco Bay, Maine

Figure 22(c): Sand bud get for Saco Bay from 1955-1991.

35 Kelley and others maining 0.8 x 106 m3 was dis persed along the shoreface, lost sea - equilib rium is attempted, ex tend ing the Camp Ellis sce nario of ward, or re mains buried in tidal delta depos it s (Figure 22b). This houses fall ing into the sea, block by block, along the beach. Pine result s in an annual input from the beach to the shoreface of 3.6 x Point, on the other hand, will conti nue to accrete sand, al though 105 m3 betwee n 1859-1955. at a de creased rate as the sup ply from the south de clines. In side the Scarborough River, parti al cutof f of sand from the beach by the short jetty will con trib ute to lo cal ero sion. The cen tral part of A Sand Budget for Saco Bay: 1955 to 1991 the Saco Bay sys tem (Ocean Park, Old Or chard Beach, and Surfside) ap pears rela tively stable and bypasses sand, yet as rel a - Dur ing the most re cent time in ter val un der con sid er ation, tive sea level con tin ues to rise, shoreline retreat is likely in this 1955-1991, en gi neer ing struc tures con tin ued to al ter sand part of the system as well. depositional patter ns in the bay. Despit e the construc tion of a Inlet s, such as Goosefare Brook, and the form er Littl e jetty at the end of Pine Point to pre vent further shoal ing of the River in let, are and were links to the back-bar rier marsh sys tems, Scarborough River Inlet , an aver age of 2.23 x 104 m3/yr of sand that open, close, and migrat e over histor i cal and geologi c time has been dredged from that channel (Table 1). After the initi al peri ods. During se vere storms, new inlet s could form from a dredging, we esti mate 1.7 x 104 m3/yr of sand reaches the in let. proces s of land-to-sea breaching, as docu m ented in Cape Cod Army record s are un clear about the ul tim ate dis posal site of all (Oldale, 1992) and elsewher e. For mer in let loca tions are par tic- this sand, but indi cat e that most of it went to an offshore, “open ular ly vulner a ble to this breaching becaus e of their morphol ogy , water” site (Figure 22c; Table 1). hydrol ogy , and under ly ing geologic and stratigraphic control. Alm ost all of the 8,500 m3/yr of sand dredged from the Several factors could disturb the pres ent sedi m ent budget. Saco River has been directly de pos ited on the ad ja cent beach at First, construc tion of sea walls, busi nesses, houses, highrises, Camp Ellis (Figure 22c). This sand has rapidl y moved to the and other in va sive coastal structures have al ready re sulted in a north and blocked the Goosefare Brook inlet follow ing disposal loss of nat ural sand exchange pathway s betwee n the beach and events. The most re cent closure of the inlet in 1993 re quired the dunes. Dune sand is a major reser voir that the beach system must use of heavy construc tion equipm ent to re-es tabli sh the channel occa sion all y draw on to survive great storms and rising rela ti ve (L. Mitch ell, Saco City Ad min is tra tor, per sonal com mu ni ca - sea level. Wall ing up all of the Saco Bay dune sand would re - tion). This channel is require d to ac com modate ef fluent from the move betwee n 5% and 10% of the total sand budget of the sys- Old Or chard sew age treatment facility on Goosefare Brook. tem (assum ing 2 or 4 m dune thickness, respec tively). Such a The beach at Pine Point has conti nued to build out, even as loss would leave the beach system with no flexi bil ity in the fu - the beach at Camp Ellis has conti nued to recede (Figures 17, 18). ture and transform it over time into a coast lacking beaches like The infil ling rate in the Scarborough River channel, 1.7 x 104 the New Jersey shore. New Jersey will spend more than 1 bil lion m3/yr, is more than twice the av er age rate of dredged sand dis - dollar s replen ish ing its beaches in the next decade (Pilkey, per- posal on the beach at Camp Ellis. This implies that the dif fer - sonal com mu ni ca tion). Ul ti mately, such un checked de vel op - ence, ap prox i mately 8,500 m3/yr, com es from: (1) sand that is ment in Maine would re sult in the loss of the primary aes thetic deli vered by the Saco River and by passes the anchor age, (2) and econom ic draw to the area, the uninterrupted stretch of clean spoils from the Scarborough River which re-enter the inlet , or (3) sandy beaches. conti nued sand rework ing from the southern beach and Sec ond, an in creased rate of rel ative sea-level rise could shoreface. Re gard less of the ulti m ate source, Pine Point ap pears cause in creased shore line re treat, erod ing pres ent prop er ties and to re ceive a mini m um of 8,500 m3/yr of sand from both the struc tures. This re ces sion is a natu ral pro cess of re-es tab lish ing shoreface and from the longshore drift. profil es of equili brium . When inter fered with by engi neer ing struc tures, or where dunes have been rem oved or built upon, sea-level rise can be come an accel er ating process of instability. The Present Status of Saco Bay, and Recom men da ti ons for Our rec om men da tions for man age ment are straight for- Beach Man age ment ward. Sedi m ents dredged from either the Saco or Scarborough River should be returne d to the south end of the system , at Camp Saco Bay is pres ently fac ing po liti cal and eco nomic issues Ellis. This is ini tially more expen sive than offshore disposal , but concern ing its beaches and harbors that are strongly influ ence d wise re lo cation of sandy dredged mate rial de creases the need for by geologi c proces ses of sand movem ent, but also by engi neer - later nourish m ent and provides some protec tion to the beaches. ing and land-use practi ces. The erosion of Camp Ellis conti nues Even with beach nourish m ent, erosion is likely to occur . In the as on shore, re fracted and jetty-re flected waves strip away sed i- long run, pub lic ac qui si tion of en dan gered prop er ties in Camp ment and attac k wooden bulkheads and sand em bankm ents. Ellis for a park is an opti mal solu ti on. Proper ti es near pres ent This erosion will conti nue, since the jet ties have starved the for- and his tor i cal in lets should be rec og nized as es pe cially vul ner a- mer ebb-tidal-delta sys tem of sand. It is likely that the zone of ble to shoreli ne changes, and devel op m ent of any type, but shoreli ne retre at will extend farther north as a new geolog i cal especially highrise structures, should be precluded.

36 A Sand Budget for Saco Bay, Maine

CONCLUSIONS of most of the bay’s sand dunes leaves littl e room for flexi bil ity as rel ative sea level con tin ues to rise, possibly at increasing rates. Sedi m ent budgets are dif ficult to fully quanti fy, but pro- The long-term nature of shoreli ne retre at in the southern vide a guide to sources, path ways, and sinks of mate ria l. We part of the beach, the history of propert y destruc tion, and the have ex am ined these trans port path ways on sev eral time scales: presence of the north jetty at the river mouth suggest s that build- geologi c (past 7,000 yrs), histori c (past 100 years), and modern ings in jeopardy may need to be moved. Al though the rate of re- (past 40 years). It is clear that an exam ina ti on of the geologi c and treat has slowed since the early 20th cen tury, the sed im ent geomorphic data, cou pled with mea sure ment of rep re sen ta tive budget does not balance in some loca ti ons. Beach nourish m ent pro cesses of sed im ent trans fer, give a more complete and ac cu - and building re loca ti on are long-term solu ti ons that should be rate descri pti on of the forces modi fy ing the beaches and inlet s of consid ered to manage the dynamic shoreline of Saco Bay. Saco Bay than exist ing models . Phys ical and num eri cal models If the Scarborough River inlet is dredged again, as planned, are useful tools, but are often incom plete, and com monly ignore sandy spoils should be returne d to the Camp Ellis beach. Al - geologi c infor m ati on on past changes in a sys tem. We feel that a though initi ally more costly than local disposal , the avoided cost mistake was made in the early years of USACOE manip u lation of a longer return time for the sand and the savings in propert y of the Saco River mouth. Sand is dom inantl y moving south to protec ted as it returns jus tify moving sand to Camp Ellis, from north in the system , and is suppli ed by the Saco River, not the re- whence it ulti m ately came. verse. Thus, the jet ties are inter fering with the overall supply of The re moval of the jet ties at the Saco River mouth is jus ti - sedi m ent to the beaches, rather than protec ting the river mouth fied geolog i cal ly, but proba bly not econom ical ly. For the long from a ficti tious infill derive d from north to south sand term, how ever, the jet ties’ det ri men tal ef fects on the beach will movement. Our primary conclusions from this project are listed re quire con tin ual main te nance dredg ing and nour ish ment, below. and/or publi c ac quisi ti on of proper ti es in Camp Ellis. The day The Saco River is the prim ary source of sand to the Saco may come when the publi c will be faced with the questi on of Bay beach sys tem, and has been so through the late Ho locene . whether it wants a harbor at Camp Ellis or a beach in southern This fact is doc um ented by hy drographi c obser va ti ons in the Saco Bay. river, side-scan sonar mapping of flow-oriente d river bedforms, and textura l data from the river sedi m ents. An offshore glacia l sedi m ent de posit may have been a local ly im portant source of ACKNOWLEDGMENTS coarse-grained sedi m ent be fore the middle Holo cene , but off- shore side-scan sonar and seis mic-refle cti on records and bottom We wish to ac knowledge sup port for this project for the sedi m ent texture reveal that it is no longer im portant . Our best ME-NH Sea Grant Program (Grant # NA16RG0157) and the esti mate is that the Saco River contri butes betwee n 10,000 to MA Sea Grant (Grant # R/CE 209). Addi ti onal support for off- 16,000 m3/yr of sand to the bay, mostly during the spring freshet. shore cores was provided by coop er a ti ve agreem ent num ber All sand accu m ulat ing in the Saco River navi ga ti on channel and 14-35-0001-30643 from the U.S. Miner als Manage m ent Ser- federal anchorages comes from the Saco River. vice. Shoreli ne change was made pos sible by a grant from the The net di recti on of sand movem ent in the bay has been and Maine State Plan ning Of fice un der the Coastal Zone Man age - rem ains from south to north. This is docu m ented by the ori enta - ment Act of 1972, as amended, pur suant to Award tion of paleospits visi ble in aeria l photo graphs and in NA27OZ0310-01 adm inis ter ed by the Of fice of Ocean and ground-pene tra ting ra dar records. It is further supporte d by Coastal Resour ce Man age ment of the Na tional Oce anic and At- changes inferred from histor i cal bathymetric and topo graphi c mo spheric Ad min is tra tion. The Maine Geo log i cal Sur vey pro- maps which depict the transfer of al most 6 x 106 m3 of sand from vided car to graphic as sis tance and the Na tional Sci ence the Camp Ellis area to Pine Point betwee n the middle 19th and Foun da tion Ex per i men tal Pro gram to Stim u late Competitive 20th centu rie s. Contem porary movem ent of sand from south to Research (EPSCoR) provided radiocarbon dates. north is indi cat ed by the rapid disap pear ance of dredged sand placed on Camp Ellis, and the coin ci den tal closure of Goosefare Brook in let and the ap pear ance of the same dredged mate rial all REFERENCES along the beach. The conti nued erosion of Camp Ellis may be di- rectly contributing to the further growth of Pine Point. Ashley, G. M. Wellner, R. W., Esker, D., and Sheridan, R. E., 1991, Clastic se - The frag ile balance be tween ero sion and ac cre tion along quences de vel oped dur ing late Quater nary glacio-eustatic sea-level fluc - tua tions on a passive margin: exam ple from the inner con tinen tal shelf much of the Saco Bay shore line supports regu la ti ons restri cting near Barnegat In let, New Jer sey: Geo log i cal So ci ety of Amer ica, Bul le - fur ther large-scale al ter ation of the coastal zone. There is no way tin, v. 103, p. 1607-1621. at present to predict whether the erosion in the southern part of Barber, D., 1995, Holo cene depositional history and mod ern sand budget of in- the bay will be restri cted to that area or extend north of ner Saco Bay, Maine: M.S. the sis, Uni ver sity of Maine, Orono, Maine, 178 p. Goosefare Brook. The large-scale engi neer ing and de velop m ent

37 Kelley and others

Barnhardt, W. A., Belknap, D. F., and Kelley, J. T., 1994, The iso static compo - Dickson, S. M., in prep., The role of storm-gener ated com bined flows in nent of postglacial rela tive sea-level change in coastal Maine, USA: Pro - shoreface and in ner con tinen tal shelf sedi m ent erosion, transport, and de- ceed ings, Lit to ral 94, 2nd In ter na tional Sym po sium, Eu ro pean Coastal po si tion: Ph.D. dis ser ta tion, School of Ma rine Sci ences, Uni ver sity of Zone Asso ci a tion for Science and Tech nology, Lisbon, 26-29 Sept., 7 p. Maine, Orono, Maine. Barnhardt, W. A., Gehrels, W. R., Belknap, D. F., and Kelley, J. T., 1995, Late Dickson, S. M., and Kelley, J. T., 1993, Shoreline change of Maine Beaches us- Qua ternary rela tive sea-level change in the west ern Gulf of Maine; ev i - ing a highly precise measure m ent technique from histori c air photo - dence for a migrat ing glacial forebulge: Geol ogy, v. 23, no. 4, p. graphs: Geo log i cal So ci ety of Amer ica, Ab stracts with Pro grams, v. 25, 317-320. p. A-444. Bart lett, W., Niel sen, J. T., Morrill, R. A., Haskell, C. R. Adamik, J. T., and Hig - Dickson, S. M., Kelley, J. T., and Belknap, D. F., 1993a, Storm-induced sand gins, W. B., 1975 - 1993, Water resource s data: Saco River, Maine: Wa- transport and bedform gene sis at beach and shoreface envi ron m ents of ter Years 1975 - 1993: U.S. Geo log i cal Sur vey, Water-Data Reports the Maine coast: Geo log i cal So ci ety of America, Ab stracts with Pro - ME-75-1 to 93-1, variable page numbers. grams, v. 25, p. 12. Belknap, D. F., and Kraft, J. C., 1981, Preser va tion poten tial of transgressive Dick son, S. M., Kelley, J. T., Belknap, D. F., Fink, L. K., Bar ber, D. C., Fitz Ger - coastal lithosomes on the U.S. At lantic Shelf: Marine Geol ogy, v. 41, p. ald, D. M., and van Heteren, S., 1993b, A sedi m ent budget for Saco Bay, 419-442. Maine, and an eval u ation of the long- and short-term geologic and ocean- Belknap, D. F., and Kraft, J. C., 1985, In fluence of ante ced ent geol ogy on evolu - o graphic pro cesses, in List, J.H. (ed i tor), Large-scale coastal be hav ior tion of bar rier sys tems, in Oertel, G., and Leatherman, S.P. (ed i tors), Bar - ‘93: U.S.Geolog i cal Survey, Open-File Report 93-381, p. 48-51. rier Is land Spe cial Issue: Marine Geol ogy, v. 63, p. 235-262. Dubois, R. N., 1992, A re-evalu ation of Bruun’s Rule and support ing evi dence: Belknap, D. F., and Shipp, R. C., 1991, Seism ic stratig ra phy of gla cial marine Journal of Coastal Resear ch, v. 8, p. 618-628. units, Maine inner shelf, in Ander son, J.B., and Ashley, G.M. (edi tors) , Duffy, W., Belknap, D. F., and Kelley, J.T., 1989, Morphol ogy and stra tigra phy Gla cial ma rine sed i men ta tion; Paleoclimatic sig nif i cance: Geo log i cal of small barrie r-lagoon system s in Maine: Marine Geol ogy, v. 88, p. Soci ety of America, Special Paper 261, p. 137-157. 243-262. Belknap, D. F., Andersen, B. G., An der son, R. S., An der son, W. A., Borns, H. Em ery, K. O., 1961, A sim ple method of measur ing beach profiles: Lim nology W., Jr., Ja cob son, G. W., Kelley, J. T., Shipp, R. C., Smith, D. C., and Oceanog raphy, v. 6, p. 90-93. Stuckenrath, R., Jr., Thompson , W. B., and Tyler, D. A., 1987, Late Qua - Farrell, S. C., 1970, Sedi m ent dis tri bu tion and hy drody nam ics: Saco and ternary sea-level changes in Maine, in Nummedal, D., Pilkey, O. H., and Scarboro Rivers es tu aries, Maine: M.S. the sis, Uni ver sity of Mas sa chu - Howard, J. D. (edi tors) , Sea level fluctu a tion and coastal evolu tion: So - setts, Amherst, 129 p. ci ety of Eco nomic Pa le on tol o gists and Min er al o gists, Spe cial Farrell, S. C., 1972, Present coastal processe s, recorde d changes, and the post- Publication 41, p. 71-85. Pleis to cene geo logic re cord of Saco Bay, Maine: Ph.D. dis ser ta tion, Belknap, D. F., Kelley, J. T., and Robbins, D. H. W., 1988, Sedi m ent dy nam ics of Univer sity of Masssachusetts, Amherst, 296 p. the nearshore Gulf of Maine: subm ersible ex peri m enta tion and rem ote Fenster, M., and Dolan, R., 1994, Large-scale rever sals in shoreline trends along sensing, in Babb, I., and DeLuca, M. (edi tors) , Benthic produc tiv ity and the U.S. mid-Atlan tic coast: Geol ogy, v. 22, p. 543-546. marine re sources of the Gulf of Maine: NOAA Na tional Un der sea Re - Fitz Ger ald, D. M., 1988, Shore line ero sional-depositional pro cesses as so ci ated search Pro gram, Resear ch Report 88-3, p. 143-176. with tidal in lets, in Aubrey, D. G., and Weishar, L. (ed i tors), Hydro dy - Belknap, D. F., Shipp, R. C., Kelley, J. T., and Schnitker, D., 1989a, namic sed im ent dy nam ics of tidal inlets : Springer-Verlag, p. 186-225. Depositional sequence mod eling of Late Quater nary geologic history , Fitz Ger ald, D. M., Lin coln, J. M., Fink, L. K., and Caldwell, D. W., 1989, west-cen tral Maine coast, in, Tucker, R. D., and Marvinney, R.G. (ed i - Morphodynamics of tidal inlet system s in Maine, in Tucker, R. D., and tors), Stud ies in Maine geol ogy; Volum e 5 - Quater nary geol ogy: Maine Marvinney, R. G. (edi tors) , Stud ies in Maine geol ogy; Volum e 5 - Qua- Geo log i cal Survey, p. 29-46. ter nary ge ol ogy: Maine Geo log i cal Sur vey, p. 67-96. Belknap, D. F., Shipp, R. C., Stuckenrath, R., Jr., Kelley, J. T., and Borns, H. W., Fitz Ger ald, D. M., Manthorp, P. A., Kuo, C. H., Van Heteren, S., Fink, K. L., Jr., Jr., 1989b, Holo cene sea-level change in coastal Maine, in Ander son, and Kelley, J. T., 1993, Estuarine circu la tion and sedi m ent transport W.A., and Borns, H. W., Jr. (ed i tors), Neotectonics of Maine: stud ies in trends in the lower Saco River: Geo log i cal So ci ety of America, North - seis mic ity, crustal warp ing, and sea-level change: Maine Geo log i cal east ern Section, 28th Annual Meeting, Ab stracts with Pro grams, v. 25, Survey, Bulle tin 40, p. 85-105. no. 2, p. 15. Bloom, A. L., 1963, Late-Pleisto cene fluctu a tions of sea level and postglacial Folk, R. L., 1974, Petrol ogy of sedi m entar y rocks: Hemphill Pub lishing Co., and crustal reboun d in coastal Maine: Amer i can Journal of Sci ence, v. Austin, Texas, 184 p. 261, p. 862-879. Forbes, D. L., Boyd, R., and Shaw, J., 1991, Late Quater nary sedi m enta tion and Boyd, R., Bowen, A. J., and Hall, R. K., 1987, An evolu tion ary model for sea level changes on the in ner Sco tian shelf: Con ti nen tal Shelf Research, transgressive sedi m enta tion on the east ern shore of Nova Scotia, in Fitz- v. 11, p. 1155-1179. Gerald, D.M., and Rosen, P.S. (ed i tors), Gla ci ated coasts: Ac adem ic Gehrels, W. R., Belknap, D. F., Pearce, B. R., and Gong, B., 1995, Mod el ing the Press, San Diego, p. 87-114. con tri bu tion of M2 tidal ampli fi ca tion to the Holo cene rise of mean high water in the Gulf of Maine and Bruun, P., 1962, Sealevel rise as a cause of shore erosion: Jour nal of the Water - the Bay of Fundy: Marine Ge olog y, v. 124, p. 71-85. ways and Har bors Di vi sion, Amer i can So ci ety of Civil En gi neers, Pro- Hess, L., and Har ris, W. H., 1987a, Morphol ogy and sedi m ent budget dur ing re - ceedings, v. 88, p. 117-130. cent evo lu tion of a bar rier beach, Rockaway, New York: North east ern Bruun, P., 1988, The Bruun Rule of ero sion by sea-level rise: a dis cussion of Geol ogy, v. 9, p. 94-109. large-scale two- and three-di men sional us ages: Jour nal of Coastal Re - Hess, L., and Har ris, W. H., 1987b, Effect of storm energy and shore line engi - search, v. 4, p. 627-648. neer ing on the sed i ment bud get of a bar rier beach, Rockaway, New York: Carter, R. W. G., 1988, Coastal Envi ron m ents: Aca dem ic Press, London, 617 p. Northeast ern Geol ogy, v. 9, p. 110-115. Davidson-Ar nott, R. G. D., and Greenwood, B., 1976, Facies rela tion ships on a Hunter, R. E., Clifton, H. E., and Phillips, R. L., 1979, Depositional pro cesses, barred coast, Kouchibouguac Bay, New Bruns wick, Can ada, in Da vis, R. sed i men tary struc tures, and pre dicted ver ti cal se quences in barred A., Jr., and Ethington, R. L. (ed itors) , Beach and nearshore sedi m enta - nearshore system s, south ern Ore gon coast: Journal of Sed im entar y Pe - tion: So ci ety of Eco nomic Pa le on tol o gists and Min er al o gists, Spe cial trol ogy, v. 49, p. 711-726. Paper 24, p. 149-168. Hulmes, L. J., 1980, Ho locene stra tigra phy and geom orphol ogy of the Hills Dean, R. G., and Work, P. A., 1993, In ter action of navi ga tional entra nces with Beach/Fletcher Neck tombolo sys tem, Biddeford, Maine: M.S. the sis, ad ja cent shorelines: Jour nal of Coastal Re search, Spe cial Is sue 18, p. Uni ver sity of Del a ware, New ark, 108 p. 91-110.

38 A Sand Budget for Saco Bay, Maine

Hulmes, L. J., 1981, Ho locene stra tigra phy and geomorpohology of the Hills Lanesky, D. E., Lo gan, B. W., Brown, R. G., and Hine, A. C., 1979, A new ap - Beach / Fletcher Neck tombolo sys tem, Biddeford, Maine: North east ern proach to porta ble vibracoring under wa ter and on land: Journal of Sed i- Geol ogy, v. 3, p. 197-201. mentar y Pe trol ogy, v. 49, p. 654-657. Hussey, A. M., II, 1959, Age of intertidal tree stumps at Wells Beach and List, J. H., Jaffe, B. E., and Sallenger, A. H., 1991, Large-scale coastal evo lu tion Kennebunk Beach, Maine: Jour nal of Sedi m entar y Pe trol ogy, v. 29, p. of Lou i si ana’s bar rier is lands: Coastal Sed i ments ‘91, Pro ceed ings, Spe- 464-465. ci al ity Con fer ence/WR Div./ASCE, p. 1532-1546. Hussey, A. M., II, 1970, Obser va tions on the ori gin and devel op ment of the Luepke, G., and Grosz, A. E., 1986. Distri bu tion of eco nomic heavy miner als in Wells Beach area, Maine: Maine Geo log i cal Sur vey, Bul le tin 23, p. sedi m ents of Saco Bay, Maine: U.S. Geolog i cal Survey, Bulle tin 1681, 58-68. 12 p. Jacob son, H. A., 1988, Histor i cal de velop ment of the saltmarsh at Wells, Maine: Lyles, S. D., Hickman, L. E., Jr., and Debaugh, H. A., Jr., 1988, Sea Level vari a - Earth Sur face Processe s and Land forms, v. 13, p. 475-486. tions for the United States 1855-1986: NOAA-NOS Of fice of Ocean og - Jensen, R. E., 1983, At lan tic coast hindcast, shal low wa ter, sig nif i cant wave in - raphy and Marine Assess m ent, Rockville, Md., 182 p. for ma tion: U.S. Army Corps of En gi neers, Wa ter ways Ex per i ment Sta- Maine State Planning Office, 1979, A study of beach processe s and manage m ent tion, Hydrau lics Lab., WIS Report 9. al terna tives for Saco Bay: Maine State Plan ning Of fice Re port, Augusta, Johnson, D., 1925, The New England- Acadian shoreline, facsim ile ed.: Hafner Maine, 82 p. Publish ing Co., 1967, New York, 608 p. Manthorp, P. A., 1995, Estuarine circu la tion and sedi m ent transport in the Saco Kelley, J. T., 1989, A pre lim inary analy sis of the miner al ogy of glaciomarine River estu ary , ME: M.S. thesis, Boston Uni versity , Boston, MA, 230 p. mud from the western margin of the Gulf of Maine: Northeast Geol ogy, Manthorp, P. A., Fitz Ger ald, D. M., Mc Kin lay, P. A., van Heteren, S., and v. 11, p. 141-151. Kelley, J. T., 1994, The ef fects of spring freshets in the lower Saco River, Kelley, J. T., and Belknap, D. F., 1991, Physi og raphy, surficial sedi m ents and Maine: Geo log i cal So ci ety of Amer ica, Ab stracts with Pro grams, v. 26, Qua ter nary stra tig ra phy of the in ner con ti nen tal shelf and nearshore re- no. 3, p. 58. gion of cen tral Maine, United States of America: Con tinen tal Shelf Re - Mahoosuc Corpo ration, 1982, A dredge manage m ent study for Maine: Maine search, v. 11, p. 1265-1283. State Plan ning Office, Augusta, Maine, 52 p. Kelley, J. T., Kelley, A. R., Belknap, D. F., and Shipp, R. C., 1986, Vari abil ity in Millette, P. M., 1993, Plant com mu ni ties as in di cators of salt marsh hy drol ogy? the evolu tion of two adja cent bed rock-framed estu ar ies in Maine, in A study at Goose Fare Brook, Saco, Maine: Geolog ical So ciety of Amer - Wolfe, D. A. (ed i tor), Estuarine vari abil ity: Aca dem ic Press, Or lando, p. ica, North east ern Section, 28th An nual Meet ing, Ab stracts with Pro - 21-42. grams, v. 25, no. 2, p. 65. Kelley, J. T., Shipp, R. C., and Belknap, D. F., 1987, Geom orphol ogy and sedi - Millette, P. M., 1997, Marsh hy drology and stra tigra phy as they relate to plant men tary frame work of the in ner con ti nen tal shelf, south west ern Maine: zonation in Goosefare Brook Marsh, Saco, Maine: M.S. thesis, Univer - Maine Geolog i cal Survey, Open-File Report 87-9, 86 p. sity of Maine, Orono, Maine, 317 p. Kelley, J. T., Shipp, R. C., and Belknap, D. F., 1989a, Geom orphol ogy and Late Mon tello, T. M., Fitz Ger ald, D. M., van Heteren, S and Caldwell, D., 1992, The Quater nary evolu tion of the Saco Bay region, in Tucker, R. D., and stra tig ra phy and evo lu tion of the Wells bar rier sys tem: Un pub lished re- Marvinney, R. G. (edi tors) , Stud ies in Maine geol ogy; Volum e 5 - Qua- port, Boston Uni ver sity, Wells National Estuarine Re search Reserve, 11 ter nary geol ogy: Maine Geolog i cal Survey, p. 47- 65. p. Kelley, J. T., Shipp, R. C., and Belknap, D. F., 1989b, Sedi m entar y framework of Na tional Oce anic and At mo spheric Ad min is tra tion (NOAA) / Na tional Ocean the south ern Maine in ner conti nen tal shelf: influ ence of glaci ation and Ser vice (NOS), Chart 13287, Saco Bay and Vicin ity , scale 1:20,000. sea-level change: Marine Geol ogy, v. 90, p. 139-147. Nelson, B. W., 1979, Shoreline changes and physi og ra phy of Maine’s sandy Kelley, J. T., Dick son, S. M., Belknap, D. F., and Friez, J. K., 1990, Sed i men tary coastal beaches: M.S. the sis, De part ment of Ocean og raphy, Uni ver sity framework of the southern Maine in ner conti nen tal shelf: prelim inary re- of Maine, Orono, ME, 303 p. sults from vibracores: Maine Geolog i cal Survey, Open-File Report 90-1, Nelson, B. W., and Fink, L. K., Jr., 1980, Geolog i cal and botan i cal feature s of 48 p. sand beach sys tems in Maine. Maine Sea Grant Pub li cations, Bul le tin Kelley, J. T., Dick son, S. M., Belknap, D. F., and Stuckenrath, R., 1992, 14, 163 p. (origi nally publishe d by Maine State Planning Office, Crit ical Sea-level change and late Qua ter nary sed i ment ac cu mu la tion on the Areas Program , Planning Report 54) southern Maine inner conti nen tal shelf, in Fletcher, C.H., III, and Normandeau Asso ci ates , 1994, A dredged mate ria l manage m ent study for Wehmiller, J. F. (ed i tors), Qua ternary coastal sys tems of the United coastal Maine and New Hamp shire: A re port to the U.S. Army Corps of States: Soci ety of Economic Pale on tol o gists and Miner al o gists, Special En gi neers, New Eng land Di vi sion, Waltham, MA. Publication 48, p. 23-34. Oldale, R. N., 1985, Late Qua ternary sea-level his tory of New Eng land: a re view Kelley, J. T., Belknap, D. F., and Fitz Gerald, D. M., 1993, Sea-level change, of the publishe d liter a ture : Northeast ern Geol ogy, v. 7, p. 192-200. coastal processe s, and shoreline de velop ment in northern New England, Oldale, R. N., 1992, Cape Cod and the islands: the geologic story: Par nassus Im - in Cheney, J. T., and Hepburn, J. C. (edi tors) , Field trip guidebook for the prints, East Or leans, MA, 208 p. north east ern United States: Uni ver sity of Mas sa chu setts, Con tri bu tion - Pilkey, O. H., Mor ton, R. A., Kelley, J. T., and Penland, S., 1989, Coastal land Geol ogy De part ment, no. 67, v. 1, p. G1-G30. loss: Ameri can Geophys i cal Un ion, Short Course in Geol ogy, v. 2, 28th Kelley, J. T., Dick son, S. M., Belknap, D. F., Barnhardt, W. A., and Henderson, In ter na tional Geo log i cal Con gress, 73 p. M., 1994a, Giant sea-bed pockm arks: evi dence for gas escape from Bel- Pilkey, O. H., Young, R. S., Riggs, S. R., Smith, A. W. S., Wu, H., and Pilkey, W. fast Bay, Maine: Ge ology, v. 22, p. 59-62. D., 1993, The concept of shoreface profile of equi librium : a criti cal re- Kelley, J. T., Fitz Ger ald, D. M., and Manthorp, P. A., 1994b, Sea sonal vari a tion view: Journal of Coastal Resear ch, v. 9, p. 255-278. in the di rection of estuarine sed i ment and wa ter move ment, Saco Bay, Pope, D. L., Penland, S., Suter, J. R., and McBride, R. A., 1991, Ho lo cene geo - Maine: Geo log i cal So ci ety of America, Ab stracts with Pro grams, An - logic framework of the Trinity Shoal region, Lou isi ana conti nen tal shelf: nual Meeting, v. 26, no. 7, p. A-69. Gulf Coast Soci ety of SEPM Founda tion, 12th Resear ch Confer ence, Kelley, J. T., Gehrels, W. R., and Belknap, D. F., 1995, Late Ho lo cene rel ative Program and Abstra cts, p. 191-201. sea-level rise and the geo log i cal de vel op ment of tidal marshes at Wells, Pugh, D. T., 1987, Tides, surges and mean sea level: John Wiley & Sons, Maine, U.S.A.: Journal of Coastal Resear ch, v. 11, no. 1, p. 136-153. Chichester, UK, 472 p. Komar, P. D., 1983, Beach processe s and ero sion - an intro duc tion, in Komar, Shipp, R. C., 1989, Late Quater nary sea-level fluctu a tions and geologic evolu - P.D. (edi tor) , CRC Handbook of Coastal Pro cesses and Erosion: CRC tion of four embayments and adja cent in ner shelf along the northwest ern Press, Inc., Boca Raton, FL, Chap ter 1, p. 1-20. Gulf of Maine: Ph.D. dis ser ta tion, Ocean og ra phy Pro gram, Uni ver sity of Maine, 832 p.

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Shipp, R.C., Belknap, D. F., and Kelley, J. T., 1989, A subm erged shoreline on USACOE, 1961, Beach erosion control report on coop er a tive study of Hills the inner conti nen tal shelf of the Western Gulf of Maine, in Tucker, R. Beach, Biddeford, Maine: U.S. Army Corps of Engi neer s, New England D., and Marvinney, R. G.(edi tors) , Stud ies in Maine Geol ogy; Volum e 5 Di vi sion, Waltham, MA. - Qua ter nary geol ogy: Maine Geolog i cal Survey, p. 11-28. USACOE, 1976, Camp Ellis Beach, Saco, Maine: Beach ero sion re con nais - Shipp, R. C., Belknap, D. F., and Kelley, J. T., 1991, Seis mic-strati graphic and sance report: U.S. Army Corps of Engi neer s, New England Di vision, geomorphic evi dence for a post-glacial sea-level lowstand in the north- Waltham, MA. ern Gulf of Maine: Jour nal of Coastal Resear ch, v. 7, p. 341-364. USACOE, 1987, Def i nite pro ject re port, emer gency shore line pro tec tion Surf Stea, R. R., Boyd, R., Fader, G. B. J., Courtney, R. C., Scott, D. B., and Pecore, S. Street, Saco, Maine: Section 14 In vesti ga tion, U.S. Army Corps of Engi - S., 1994, Mor phol ogy and seis mic stra tig ra phy of the in ner con ti nen tal neers, New England Di vision, Waltham, MA, 15 p. shelf off Nova Sco tia, Can ada: Ev i dence for a -65m lowstand be tween USACOE, 1992, Sec tion 111 re con nais sance re port: Camp Ellis Beach, Saco, 11,650 and 11,250 C14 yr B.P.: Ma rine Geol ogy, v. 117, p. 135-154. Maine: U.S. Army Corps of Engi neer s, New England Di vision, USACOE (U.S. Army Corps of Engi neer s) , 1886, Report of the Acting Chief of Waltham, MA. the En gineer s of a survey of the Saco River: Exec u tive Docu ment 37, van Heteren, S.,1996, Preserve d records of coastal-morphologic and sea-level 49th Congress. changes in the stra tig raphy of paraglacial bar riers: Ph.D. dis ser ta tion, USACOE, 1910, Reports on the examinatinand survey of the Saco River, Maine: Boston Uni versity , Boston, MA. Docu m ent 752, 61st Congress . van Heteren, S., Fitz Ger ald, D. M., Bar ber, D. C., Kelley, J. T., and Belknap, D. USACOE, 1920, Prelim inary exam ina tion, mouth of Saco River, Maine, U.S. F., 1994a, Bed rock control on the devel op m ent of the Saco Bay, Maine, Army Corps of Engi neer s, New England Di vision, Waltham, MA. bar rier sys tem: Geo log i cal So ci ety of Amer ica, Ab stracts with Pro - USACOE (U.S. Beach Ero sion Board and Maine State Planning Board), 1935, A grams, v. 26, no. 3, p. 77. coop era tive beach erosion re port on Old Or chard Beach: (unpub lishe d), van Heteren, S., Fitz Gerald, D. M., and Mc Kin lay, P. A., 1994b, Ap pli cations of U.S. Army Corps of Engi neer s, New England Di vision, Waltham, MA. ground-pene tra ting ra dar in coastal stratigraphi c studies: GPR’94, Pro - USACOE, 1939, Pre lim i nary ex am i na tion (re view of re ports) on Saco River, ceed ings of the Fifth In ter na tional Con fer ence on Ground-Pen e trat ing Maine, U.S. Army Corps of Engi neer s, New England Di vision, Radar, June 12-16, 1994, Kitchner, Ontar io, Canada, v. 2, p. 869-881. Waltham, MA. van Heteren, S., Fitz Ger ald, D. M., Bar ber, D. C., Kelley, J. T., and Belknap, D. USACOE, 1955, Beach erosion control report on coop er a tive study of Saco, F., 1996, Vol u metric analy sis of a New England bar rier system using Maine: U.S. Army Corps of Engi neer s, New England Di vision, ground-pen e trat ing-ra dar and cor ing tech niques: Jour nal of Ge ol ogy, v. Waltham, MA. 104, p. 471-483.

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