Shoreline Changes Along the Southeastern Coast of Martha's Vineyard, Massachusetts for the Past 200 Years

QUATERNARY RESEARCH 4, 496-508 (1974)

J. GORDON OGDEN III1

Received February BO, 1978

Shoreline changes since 1776, including two 30-yr periods separated by nearly 100 yr are documented from surveys, topographic maps, harbor charts, and aerial photographs for the southeastern corner of the island of Martha's Vineyard, Massachusetts (41 °25' N, 70°35' W). From 1776 to 1969, a. barrier beach has receded by more than 880 m, an average rate of 4.6 m/yr. A series of four detailed surveys from 1840 to 1886 document consistent shoreline retreat in this area of 3.1 m/yr. For the period 1938-1969, planimetry from aerial photographs and field observation ind.i~ cate that more than 28 ha. a.nd nearly 3 X l(f m' of foreland composed of till have washed a.way. A house, located 200 m from the cliff edge of the foreland in 1938 was only 56 m from the cliff edge in July 1972. Violent storms were associated with the opening of the bay behind the barrier beach in nearly the same location in 1856, 1886, 1938, and 1954. Easterly migration of the opening results in rapid erosion of the southeastern corner of the island (Wasque Point) and even~ tual closing of the opening. Field observation of the 1954 opening indicates that the mechanism of failure of the barrier beach is primarily by storm tide-induced subsidence. Subsequently, strong (up to 1.2 mps) easterly currents cause migration of the opening to the east and closure within 15 yr. A summary review of evidence for changes in sea level in the past is suggested in partial explanation for the consistent shoreline retreat described in this paper.

INTRODUCTION crops in several localities, and in some in Martha's Vineyard is an island of ap stances (Gay Head at the southwestern tip proximately 100 sq miles located in lat. of Martha's Vineyard) thrust up into 41 °25' N and long. 70°35' W. It is the steeply tilted beds of remarkable beauty largest of a group of islands south and caused by various colors in the Cretaceous southwest of Cape Cod, Massachusetts and Tertiary clays and sands (Kaye, (Fig. 1). These islands and Cape Cod form 1964a). the northernmost outposts of the Atlantic The moraines which form the northwest Coastal Plain which here dips beneath the ern coast of Martha's Vineyard have a sea and continues northeastward as maximum relief of 91 m. The topgraphy is George's Bartle The surface of t he islands steep and rolling in contrast to the very flat is of glacial drift and date from the retreat and gently sloping outwash plain to the of the Wisconsin ice sheet. Material under east. Soils of the moraine are rocky, thin, lying the drift consists of beds of unconsoli and lacking in almost every soil component dated Tertiary sands and clays which out- except sand. Deeper soils are found in the outwash plain with few rocks and little 1 Dept. of Biology, Dalhousie University, Hali clay. The southern coast is exposed to the fax, Nova Scotia, Canada. Atlantic Ocean and vigorous longshore cur-

496

-(J--S-"'°-~ ~TH

--- B ,; / I' / MARTHA'S VINEYARO / /CHAPPAQUIOOICK I / I -0 i NORTH I !Km

WASOVE PT. I•

/ / NA.S. TARGET TRACK NORTON POINT

C Fro. 1. Regional map of Cape Cod and the Offshore Islands showing location of study area. rents (velocities to 1.2 mps) have a pre coastal chart~ as well as field observations. dominantly easterly set. Transparencies were prepared from all old The following report outlines the evi charts and aerial photographs available dence for shoreline changes along the south and rescaled to 1: 24000 using H. L. Whit eastern coast of Martha's Vineyard from ing's original coordinates of lat. 41 °21'00'' 1776 t-0 1972. The 1776 shoreline was re N and long. 70°27'0()" W to long. 70°31'00'' scaled from Kaye (1973) and based on Des W. Grid ticks are indicated at 1'00" of lon Barres (1777) survey. gitude in the accompanying illustrations. Information for 1846-1886 was compiled from the detailed surveys ( 1: 10,000) of Shoreline Features-1776 Prof. H. L. Whiting (1882, 1887), and According to Kaye (1973), the Des Shaler (1888), Woodworth and Wiggles Barres (1777) map of Martha's Vineyard worth (1934), old files of the Vineyard was surveyed by plane table, and is prob Gazette in E dgartown, Massachusetts, and ably accurate to within 50 m. The shoreline records found in the archives of the Dukes position in 1776 is compared with the 1969 County Historical Society. shoreline in Fig. 2, which also shows the Data for the period 1938-1972 were com 1846 shoreline surveyed by Whiting (1887). piled from aerial photographs, USGS topo Retreat of the W asque Point foreshore was graphic maps (1: 24,000) and various approximately 880 m in the period 1776- J. GORDON OGDEN

KATAMA OPENING 1776 - 1969 WASOUE

KATAMA BAY 1969 SHORELINE

+ IA + -~ \ -~· .· ~ NORTON POINT __ _..- ('°' A ..... ·...... _.;" er' J ·-.... C .....···...... _._-:; /':,' ._·-_./ . I I - _·:;.:_·:::·:.·.:·, i~.·:::. .-:~ :~..-.-~.-::.:_-· ····"··" ~ ~~:·~H~~~INE r', ('j / "- -. -. -. ~ _ _ JI 111& SHORELINE \. J / ~ .__ ------.... - --. ) '_,,,..,./ ------

1!161 -- • 114& ··"""···· ·- ·- F..i- - - - 1770 --- soo 0 ~ 1000 1500 .....,. Fro. 2. Comparison of 1776, 1846, and 1969 shoreline at Wasque Point.

1969, for an average rate of retreat of 4.6 noted that some 368,000 m3 of material was m/yr. removed from this section during the period The 1776 shoreline indicates an opening of measurement. Family photographs and at the eastern end of Katama Bay. The re records recall that a tennis court existed on lationship of openings into Katama Bay the seaward side of East Chop drive above and erosion of Wasque are discussed in a the old steamer landing. subsequent portion of this paper. H. L. Whiting (1887) recorded that the waste of material from Cape Poge (Fig. Shoreline Changes in: the PJJri.od, lb) was auout 130 m during the period 1846- 1877 1846-1886, and that the cliff face had ap . The amount and raie of coastal weather proached to within 14 m of the lighthouse ing was of considerable interest to N. S. foundation and was continuing to wear Shaler (1888) in his detailed study of the rapidly. Owing to rapid erosion of the geology of the Vineyard, and he devoted salient at Cape Poge, the lighthouse has considerable attention to various pa~ of been moved several times. the island, as did H. L. Whiting (1887). At the time of Whiting's report, he noted Whiting noted Ulat the central portion of that Skiff's Island, southeast of Wasque W equobsque Cliffs (Fig. 1b) lost 67 m dur Point, which for most of the· period of his ing the period 1846-1886, at an average rate survey had been awash at high tide, had of 1.7 m/yr. Shaler notes "perhaps the increased to a maximum length of about most rapid gain of the sea on the land 365 m in a north-south direction and about ·where the shore is considerably elevated 88 m in an east-west direction. The island which has been observed on any part of the included about 1.8 hectares and supported New England coast." "beach weeds and grasses." Banks (1911) Erosion has· not, of course, been limited in his "History of Martha's Vineyard" rec to the southern side of the island. On the ords that salt hay was frequently harvested eastern side, the cliff face at East Chop on Skiffs Island and that for a time, sheep (Fig. lb) retreated 23 m between 1846 and were pastured there. 1871 at a rate of about 1 m/ yr. Shaler The beach 10 km W of Norton Point re- MARTHA'S VINEY ARD SHORELINE EROSION 499

1846 + +

1856 ' -1-

.:..

• • • •• \ • 1446 SHORELINE l ~ :.-::. --~ ·,:-___10 100 _ _IJ,OO .,,. Met1rs - KATAMA OPENING 1846- 1886

-t Fro. 3. Shor-eline changes ·1846--1886 at Wasque Point,. and Norton Point. From surveys by H. L. Whiting (1887). ceded a distance of 146 m in the 40-yr shoreline and illustrates the general beach period covered by Whiting's survey. Beach retreat mentioned by both Whiting and retreat at Wasque Point showed a maxi Shaler. The interval covered by Whiting's mum of 117 m. survey included two western openings, one T he 1846 shoreline (Fig. 3) is shown by of which (1886) Prof. Whiting observed dotted lines superimposed on the 1886 following its formation in a January storm. 500 J. GORDON OGDEN

Shaler ( 1887) noted that the western open Measurements from aerial photographs ings generally occur in about the same (target track to the shoreline) indicate that place near Mattakeset Bay in Katama the beach has retreated 93 m since 1944, Bay. The predominant easterly drift of the at an average rate of 3.7 m/ yr. Similar strong currents along this coast cause the measurements from 1951 and 1955 air western tip to accrete and the eastern tip photos indicate that the retreat has been to retreat until the opening comes up remarkably uniform with rates vary;ng against the Chappaquiddick shore at from 3.66 m to 3.81 m/yr. Only about one W asque Point. half of the track remained back of the T he present author had the opportunity beach sand in 1972. to witness the 1954 breakthrough at the B. Mattakeset Bay. Shoreline retreat in western end. A comparison of the western the area of Mattakeset Bay, based on openings and migration of the opening 1s aerial photographs from 1951 through 1969, considered elsewhere in this report. indicate that the beach has moved back about 85 m, at an average rate of 4.7 m/yr. Shoreline Changes in the Period C. Norton Point. Because of periodic 1938-1972 aggradation of the point when western Aerial photographs from flights in 1938, openings develop into Katama Bay, the 1944, 1948, 1951, 1955, 1963, and 1969, to shoreline appears deceptively stable. Five gether with a topographic map (USGS 7.5' measurements at 500-m intervals from the series, Edgartown, Mass.) and coastal western to eastern terminus of Norton charts (USCGS) provide dramatic evidence Point show retreat of 67 m, 15 m, 0, 15 m, of continuing instability of the coastline in and 180 m, giving an average retreat of 30.5 this portion of Martha's Vineyard. Aerial during the 18-yr period 1951-1969 or a rate photography provides additional detail on of 1.7 m/yr. Comparison with the 1846 coastal features not available from topog shoreline, however, shows retreat in excess raphic maps (10-ft (3.04 m) contours), or of 300 m during the 123 period, an average coastal charts. rate of 2.5 m/yr. Similarily, the 1776 profile Shoreline changes from H)38 to 1960 are shows a loss of about 600 m, for a rate summarized in Fig. 4, which shows the mi slightly more than 3 m/yr. gration of the opening and overall retreat D. Wasq-ue Point. Since 1846, the maxi of the beach during the 31-yr period. A mum retreat of the outer beach at Wasque comparison of the shoreline in 1776, 1846, Point is approximately 310 m, an average and 1969 is shown as Fig. 2, together with rate of retreat of 1.7 m/yr. This part of the position of the cliff face at Wasque the shoreline periodically progrades when Point in 1948 and 1969. Because of the de there is a western opening. Each time the tail available from aerial photography, opening moves eastward against the cliffs shoreline changes are described below for at W asque Point, however, retreat is excep separate sections of the region (A-D in Fig. tionally rapid. As shown in Fig. 2, the sa 2). lient of Wasque Point has retreated more A. Ta,rget Track, Naval Air Station, than any other portion of the shoreline. Katama. In the early 1940s visitors to the E. Wasque Cliff. The retreat of Wasque Island recall a target track (Fig. le), par Cliff is even more dramatic than the retreat. allel to the shore, measuring about 15 m of the old target track west of Mattakeset wide and 430 m long with a massive con Bay (A in Fig. 2). Reference points on crete bunker located in the center of the aerial photographs include the cliff face, old track on the shore side. In 1944, the south roads, a rectangular woodland, and the ern side of the track and the bunker were position of a cottage at Wasque Point. more than 60 m from the high-tide line. From west to cast along the shore, retreat MARTilA1S VINEYARD SIIORELINE EROSION :501

KATAMA OPENING 1938 -1969

+ '

C T +

+ +

------~---~

)00 1000 1$00 \000 0 1000 2000 3000 ,ooo 5000 . -T------.--- -~ Fe el Mete,s FIG. 4. Shoreline changes at Wasque Point 1938-1969. since 1948 is measured at 198 m, 230 m, ward at a uniform grade of 3%. In July 213 m, 238 m, and 152 m, at approximately 1972, the cliff face was approximately 9 m 200-m intervals, an average retreat of 206 high for a distance of approximately 1000 m. In 1948, the cliff face at the center of m, and tapered sharply to the beach to the the section was less than 2 m high, and east and west. The volume of earth lost to tapered both east and west to intersect the the sea is estimated at more than 3 X 105 beach sand. Landward, ground sloped up- m3 over a 21-yr period (1947-1969), with 502 J. GORDON OGDEN

+ - 1955- +

-._ ... _...

WESTERN OPENINGS - KA TAMA BAY 1856 - 1955 Fm. 5. Western openings into Katama. Bay, 1856-1955. 1938 (-.-.); 1955 (- - ); 1880 ( .....) ; 1856 (- ---). a yearly nMeaL for Lhis period of nearly appearance of the island was in 1938, at 10 m. The cliff does not wear away at a which time it was approximately 2 ha in uniform rate, however, as the face is rela extent with a maximum relief of 9 m, and tively stable until K atama opening sweeps supported a solid cover of marram grass eastward and slices off another large por (Ammophiln breviligulata) and marsh tion of Wasque Point. The rate of cliff re grass (Spartina aller11.:iftcrra) . T he i1:,h111d treat here at present is slower than in t he was nearly bisected in the 1938 hurricane period 1948-1955 due to the increased and had disappeared by 1942, and has height of the cliffs and the additional vol existed since that time as a shoal exposed ume of earth to be removed with each foot only at low tide. of cliff retreat. T he old cottage at W asque Point is in WESTERN OPENINGS OF KATAMA creasingly threatened by the migration of DAY AND EASTWARD MIGRATION the cliff face. An aerial photograph taken OF NORTON POINT after the 1938 hurricane showed the house to be 196.5 m from the cliff edge. In 1948, Figure 5 shows the positions of western t he house was 167.6 m from the 1-m high openings to K atama Bay in 1856, 1886, "cliff" that separated the till of the cliff from l938, 11.rni 1955. H. L . Whiting wit.nP.88erl beach sand. By 1951, the cliff had been cut the formation of one open:ng and reported back to within 135 m of the house, and in his observations in his Appendix t-0 Shaler's 1955 further retreat had reduced the dis report. An excerpt from h:s record follows: tance to the cliff face to less than 100 m. In November 1969 the house was within 76 The new opening through Cotamy [sic) beach (so called) occurred on the night of m of the cliff face, and a tape measurement January 9-10, 1886. After a gale from the in July 1972 showed the cliff to be within ENE, the wind shifted to WSW, still blowing 56 m of the house foundations. The amount a gale. The "west beach," as the portion west of land lost to the sea at this point from of the new inlet is now called, was quite low 1938 to 1969 is approximately 28 ha, with before this gale occured, and after the shift of wind the whole beach, in long-shore phase, 20 ha lost since 1948. was a ''breaker." A very high tide, one of the F. Skiff's Island. Located about 2 km SE highest in this locality since the Minot gale, of W asque Point (Fig. 1b) , Skiff's Island accompained this storm. The general opinion is a transitory feature formed infrequently is that at the time of the high tide of the bay by shifting sands and currents in the off the opening was first made by the out-going or southerly current. As soon as t.he beach shore area. Historical records (Shaler, could be visited for observation t.he opening 1888) indicate that it was occasionally med was already, by estimate, about one hundred .for summer pasturage for sheep;- The last . yards -in width . • . (Shaler; 1888 :36Z.)· UAR'T'RA1S VTN'F.YA°RD $110RF.T,TNF. 'F.~OS{Ol\" ,503

The Vineyard Gazette for 15 January 1886 longer competent to flush the sand away made the following observation regarding from the cliffs. When this happens, over the storm which Prof. Whiting witnessed: shoot of sand from Norton Point seals off "One of the results of Saturday's gale was t.he opening and t,he extended narrow a rm the breaking through of the South Beach of K atama Bay gradually fills in and near the ent.rance to Cotamy Bay, the first makes a broad sandy foreshore with coarse effectual opening from the harbor directly sand of remarkably uniform grain size. to the ocean in twenty years." T he report Elongation of the channel leading sea goes on to express enthusiasm for the ward from K alama Bay by the easterly mi prospect of improving the shellfish beds and gration of Norton Point causes the tides in shortening the time for vessels to reach the K atama Bay to peak at ebb or flood out rich fishing grounds southeast of Wasque of phase with the ocean tides. In addition, Point . Shoreline processes were the same because the opening of Kata.ma Bay to the then as now, however, and the opening had north through Edgartown Harbor is Jong migrated around W asque Point and closed (approx 5.5 km), tidal flushing of K ntlima again within 15 yr. Bay becomes weak, to the detriment of pro T here is a striking correspondence in the fitable shellfish beds in the lower pnrt of location of the western openings, each of the Bay. P eriodically, when the eastern them located just a little east of Mattake opening is closP

August 19541 producing widespread flooding toward Katama Bay, widening and deepen in many parts of the Island. Sand dunes, ing the "graben" I had originally observed. which had grown to a height of more than Within 30 min, a steady succession of 6 m along much of South Beach including waves approached, reached, and ext.ended Norton Point were destroyed, leaving a into Katama Bay. As each wave receded, broad narrow lowland, vulnerable to the level of the beach fell more, until within breaching by storm tides. The author had 1 hr of my arrival at the scene, it became the unique opportunity of witnessing the apparent that a new opening was in the breakthrough of the beach during the late making, as waters of Katama Bay were fol afternoon of 31 August 1954. As noted by lowing the recedence of waves from the '\¥biting for the opening of 1886, the whole Atlantic side of the beach. At this point, beach was "a breaker" with driving onshore losing track of both time and the responsi winds from the ESE. The crest of the storm bility to keep accurate notes, I observed the tide had passed, and the tide on the ocean waters of Kato.ma Buy follow retreating side of Norton Point was falling. Flood ocean waves, and effect a complete breach conditions still prevailed in Katama Bay, of the beach. A stream, at first no more however, with the waters of Herring Brook than 2-4 m wide aTJd not more than 30 cm under the bridge near Mattakesett Bay deep flowed seaward from Katama Bay, within 30 cm of the road surface. Visibility but rapidly widened and deepened to pro was sufficient to see that about 1000 m duce a sand cliff near where I stood, 2-3 m down Norton Point, seas were dashing over high and a channel at least 50 m across. the crest of the divide between Katama As water began to pour seaward from Bay and the ocean. The waves were not Kata.ma Bay, the effect on the ocean side washing into Katama Bay, but were dis of the beach was spectacular, to say the sipating into the sand well downslope on least. Where the receding waters of Katama the Katama side of the beach. Rough esti Bay met the storm waves on the ocean side, mates of elevation differences at this time a maelstrom resulted, with spray being record that the height of Katama Bay thrown high into the air both alongshore waters was at least 1.5 m below the crest and offshore of the new opening. of the beach divide, and the "average" Within 2 hr of the first breach of the water level on the ocean side was at least beach by ocean waves, the new opening was 3 m below the divide. At this time, the almost 300 m wide, and water was boiling beach was about 150-250 m wide. On walk seaward from Katama Bay. The following ing down the Katama side of the beach to morning, under clear skies and bright sun, observe the action of the waves (field notes the opening looked as if it had always been indicate no anticipation of a breakthrough there, and the tide was flowing quietly into at this time) , I observed a small "fault the Bay from the ocean. cliff" in the sand as I approached the area Figure 4 clearly indicates the rate of where the waves were washing furthest to- eastward migration of Norton Point. The !>fARTHA'S VINEYARD SHORELINE EROSION 505

TABLE 1 HtJSTVKlCAL Ri,;cvttu VF Qpi,;r;a;u::; li)l'l'V K .<1.TUIA B Ar

W. E. DA.ti> Source opening opening Remarks 1724 Southack (1694 survey) X Scale makes reliabili ty doubtful 1776 Des Barres map X Plane table survey 1795 Benj. Smith, Edgartown town X Shown at extreme E. tip of survey Wasque 1830 H. Grape, Edgartown town X Shown E. of 1846 opening survey near W asque shore 1846 H. L. Whiting, USCGS X 1856 H. L. Whiting, USCGS X X 1860 Unid. hydrographic chart X X Chart fragment in files Dukes Co. Historical Society 187L H. L . Whiting, USCGS No opening 1873 Dredged eastern opening Not successful closed before completion 1886 H. L. Whiting, USCGS X 1887 USGS 15' topographic X X 1892 Geo. W. Eldridge X X No sources, souvenir map 1897 USAGE Edgartown report X 1901 Chart no. 45 Edgartown X Gives soundings at M.L.W. Harbor, Geo. W. Eldridge 191.''> USACE Edgartown report No opening 1917 USCGS Chart no. 46 Edgar- X town Harbor 1919 USAGE report Opening attempted 1921 USACE report X Dug opening, successful 1924 USAGE report X Migrated to Chappaquiddick shore 1934 USACE report No opening 1938 Air photo GSF5-176/ 178 X X F1own Nov. 1938 following hurricane 1942 USGS 15' topographic map X Near Wasque shore 1944 Air photo USCGS C-2340 X 1948 Air photo USCGS J-965 X Near W asque shore 1951 Air photo USCGS X J-4714/ 4730 1955 Air photo USGS X Also shows opening into W-5069/5070 Pocha. Pond 1958 USCGS chart no. 346 X 1963 USCGS chart no. 261 X 1969 Air photo USGS VCIQ 1-27 /29 1970 Air photo USDA DP0-111- 10/ 11 1972 Field observation (J.G.0. 111) 1974 Field observation (J.G.O. III) ------···-··---- - . . -· - western tip of the opening (Norton Point eastern opening is similar for the 1954 proper) moved nearly 2 km eMtward opening in both distance and duration. in the period 1938-1954, an average rate of Table 1 lists available dates, sources, and approximately 107 m/ yr. Rate of migration seaward openings of Katama Bay. Whit of the point, and eventual closure of the ing's 1871 survey indicated that there was 506 J. GORDON OGDEN no opening of the Bay, although in the fall static rebound or sediment loading on the of that year, General G. K. Warren at continental shelf are dominant mechanisms tempted to create an opening near the site in sea level variation. of t.be previous ( 1R56) opP.ning, anrl vP.ry Walcott, (1972a, 1972b) shows values of close to the site of the subsequent (1886) coastal subsidence of 3 mm yr-1 for the opening. Cape Code region. Approximately 50% of The data of Jfigs. 3 and 4, together with this value is attributed to an eustatic rise the sketchy information available from in sea level, the remainder to isostatic de Table 1, indicate that following a western leveling, at least partly in response to in opening near the mouth of Mattakesett creased crustal loading on the continental Bay, the point migrates easterly around shelf. These conclusions are in agreement Wasque Point within 10-15 yr, and results with evidence presented by Grant (1970) in closing the southern end of Katama Bay. who accounts for most, if not all, of the Within a few years (5-10 from the existing recent crustal subsidence in the Maritime records), a new western opening is effected Provinces of Cana.da by increased crustal during a severe storm with unusually high loading of water and sediments on the con tides. tinental shelf. These views are in conflict with Kaye SEA LEVEL RISE AKD SHORELINE (1964b) and Kaye and Barghoorn (1964) EROSION AT WASQUE POI~T who demonstrate the stability of barnacle While storms and prevailing longshore growth limits on coastal rocks and light currents are undoubtedly competent to houses by comparing modern and historical effect the changes outlined in the previous photographs during the past century. Addi portions of thi::. paper, some aUeuUun tional evidence, based on tide gauge vari should be focused on the effect of sea level ability, and autocompaction of peat in trends, and their possible role in exacerbat coastal environments lead Kaye and Barg ing coastal management problems. hoorn to infer that sea level has fluctuated Hicks and Crosby (1974) indicate that within 45 cm of the present sea level for for periods of record ranging from 16 to 50 the past 200 yr, a conclusion generally sup yr, there has been an average rise in sea ported by Bloom (1967). 1 level of 2.6 mm yr- , based on tide gauge 'T'wo rP.l evl\nt radiocarbon dates from records at five stations from Portmouth, Martha's Vineyard also imply a continuing NH, to Newport, RI. Standard error.,; of the rise in sea level. K. M. Jones (personal trends reported by Hicks and Crosby communication) recovered a pine stump (1974) are about ±10% of the reported whose root crown was just exposed at ex values. Similarly, Meade and Emery treme low tide in April 1967 about 6 km (1971) define a mean annual rise of sea west of Katama Bay. A sample from this level of .25 cm yr-1 for the Gulf of Maine, stump gave an age of 590 ± 90 yr BP (Gx .35 cm yr-1 for the coastal section from 1-1078). The tree was rooted in gravel, and Cape Cod t'J Cape Hatt-eras, .26 cm yr-1 in situ, as p:eces of intact bark and clumps from Cape Hatteras to Key West, and .18 of gravel were recovered with a stump. cm yr-1 for the Gulf of Mexico. Since river Based on the levels of living and dying runoff into the coastal zone accounts for pines in coastal environments in other parts only 7% of the annual difference in sea of Martha's Vineyard, it is probable that level in the two northern coastal sections, the tree was killed when sea level was ap and 13 and 21 % in the southern and Gulf proximately 2 m below its present level. In of Mexico sections, respectively, these au low-lying coastal environments on Mar thors conclude that melting glaciers and tha's Vineyard, such as characterizes the coastal adjustments associated with iso- area around this sample, pine trees are not 1 }IARTHA S VINEYARD S HORELINE EROSION -507 found less than 1.5-2.0 m above mean sea mented from aerial photographs and field level, and some distance inland (100-300 observations and shows a total loss of more m). than 213 m in the period 1948-1969. The Similarly, on the northwest coast of Mar average rate of 10 m/yr for this 21-yr tha's Vineyard, a red maple (Acer rubrurn) period must rank as one of the most vigor stump was recovered in 1.2 m of water ous rates of coastal erosion anywhere the (below M .H .T.) which dated 370 ± 105 yr sea is attacking a headland of morp than BP (OW U-334, Ogden and Hay, 1973). 10 m elevation. This stump was also rooted in mineral soil, Vigorous longshore currents (up to 1.2 which decreases the probability of delevel mps) have a predominantly easterly set ing by autocompaction as suggested by and a.re competent to remove the sand to K aye and Barghoorn (1964). There are no the murh more vigorous Muskeget Climmel coastal red maple swamps at present in the waters to the east where currents to 2.2 mps vicinity since t his species (A. i-ubrum) is are common. The sands a re then d ispersed quite intolerant of salt. It is not unreason into the shoal waters E of M ar tha's Vine able to infer that sea levels were at least yard. At infrequent intervals, the conflu 1.5 m lower when this tree died. Since the ence of the easterly flowing coastal cnrrPnts tree is approximately 20 m offshore at the and the predominantly north-south cur present time, ii is also apparenL tl1aL Lhe rents of :'.viuskeget Channel produce ::{kiff'~ shoreline was many meters to the north of Island. T he last recorded appC'ar ancc of its present. position. this island was in 1938, wh<.'n it wa~ re While the evidence reviewed above is not ported to have been approximately 2 ha in conclusive, it does indicate that shorelines extent and 9 m high. \Vithin historic times in the area of Martha'sVin eyard have been it is reported to have developed sufficient unstable for more than the past 500 yr, and heaC'h grass and salt hay to have pa,-tured that in addition to shoreline erosion, rising sheep. The island was subsequently reduced sea levels have also played a part in the to a tidal shoal by a series of hurricanes shaping of the shoreline. that swept this area between 1938 and 1955. The development of a western opening SUMMARY AND CONCLUSIONS into K atama Bay from the sea and suhse Evidence from old surveys, topographic quent eastern migration around th e tip of map::-, coastal charts, aerial photographs, W asqne Point is documented for J 856, and ,field observations document more than 1886, 1938, nnars period 1951- 1909, portiun:; of Lhe shoreline :;ornewh~·re ea:sL of the rnuuLb of MaLLake showed a ronsistent retreat ranging from ,:ett Bay. 2.5 m to 4.7 m/ yr. With the C'Xception of occasional transi Cliff retreat at Wasque Point is docu- tory openings made by man in the Ponds 508 J. GORDON OGDEN

along the southern shore of Martha's Vine zard Bay, the Elizabeth Islands, Vineyard yard, there have been no major construc Sound." In "The Atlantic Neptune." London, tion works anywhere along this coast which pub!. for the British Navy. GRANT, D. R. (1970). Recent coastal submergence would account for the rapid erosion of the of the Maritime Province.s, Cnn.nda. Canadian shoreline. In view of the evidence available, Journal of Earth Science 1, 675-689. it would appear that the principal cause for K ..n, C. A. (1964a). Outlines of the Pleistocene the consistent erosion of this shore may be Geology of Martha's Vineyard, Massachusetts. explained by continuing rise of sea level U.S. Geological Survey Professional Paper 501-C, Cl39. and vigorous alongshore currents which -- (1964b). The upper limit of barnacles as effectively keep the sand in suspension until an index of sea level change on the New Eng they are dispersed in Nantucket Sound or land coast during the past 100 years. Journal the adjacent coastal shelf. of Geuluyy 72, 580-600. From the evidence presented, there can -- (1973). Map showing changes in shoreline of Martha's Vineyard, Massachusetts, during bP, little doubt that additional breaches of the past 200 years. U.S. Geologic Survey, Mis the beach will occur in future, and avail cellaneous Field Studies, Map MF-534. able data indicates that these openings will KAYE, C. A. AND BARGHOORN, E. S. (1964). Late occur near the western side of Katama Bay, quaternary sealevel change and crustal rise at following a major st-Orm coinciding with a Boston, Massachusetts, with notes on the auto compaction of peat. Geological Society of Amer high tide. Because the failure of the beach ica Bulletin 75, 63--80. is by sapping, rather than overshoot of 0GDEY, J. G. III, AND HAY, R. J. (1973). Ohio storm waves, it seems unlikely that a pro Wesleyan University natural radiocarbon mea posed 3-m high berm parallel to the beaach, surements V. Radiocarbon 15, 350----366. as recommended by the U.S. Army Corps SHALER, N. S. (1888). "Geology of Martha's Vine yard." VIIth Annual Report U.S. Geologic Sur of Engineers {USACE, 1969), can success vey, p. 297-363. fully prevent the establishment of western USACE, (1969). Edgartown Harbor, Ma.ssachu openings with Katama Bay. settts Survey Review of Reports, U.S. Army Corps of Engineers, New England Division, ACKNOWLEDGMEKTS Waltham, Mass. WALCOT'r, R. I .(1972). Past sea levels, eustasy, and Without implying any responsibility for the con deformation of the Earth. Quaternary Re8earch clusions reported in this study, I wish to acknowl 2, 1-14. edge with sincere thanks the critical and construc - - (1972b). Late quaternary vertical move tive comments of the following individuals who ment in eastern North America: Quanti ta ti ve reviewed drafts of this manuscript: K. 0. Emery, evidence of glacial-isostatic rebound. Reviews J. L. Forsyth, J. R. Hails, C. A. Kaye, V. K. Prest, of Geophysics and Space Physics 10, 849---884. and R. I. Walcott. WHITING, H. L. (1872). "Shoreline retreat at Cotamy Bay." VIIth Ann. Report, Harbor REFERENCES Commissioners, Boston, pp. 106--111. -- (1887). Recent coastal changes at Martha's BANKS, C. E. (1911). "The History of Martha's Vineyard, Massachusetts. Appendix 9, U.S. Vineyard, Massachusetts." Vol. l, General His Coast and Geodetic Survey. Annual Report. tory. Dean Co., Boston, Mass. WOODWORTH, J. B. AND WIGGLESWORTH, E. (1934). BLOOM, A. L. (1967). Pleistocene shorelines: A "Geography and Geology of the region includ new test of isostasy. Geological Society of ing Cape Cod, the Elizabeth Islands, Nantucket, America Bulletin 78, 1477-1494. Martha's Vineyard, and Block Island." Museum DEs BARRES, J. F. W. (1774-1781). "Part of Mar of Comparative Zoology, Harvard, Cambridge, tha's Vineyard and Nantucket Islands and Buz- Mass.