- The Eroding Shores of Outer Cape Cod

Transcription

1 ABOUT THE APCC The Assoiation for the Preservation of Cape Cod is a non-profit rporation whih ndts researh andpblishes position papers, informational blletins and impat stdies on environmental isses. Membership des and donations are tax-dedtible and spport researh and st of pbliations. Portions of this report may be qoted, in ntext, if properly aknowledged to the Assoiation for the Preservation of Cape Cod, n. nformation on membership and lists of pbliations are available from APCC, n., Box 636, Orleans, Mass The Eroding Shores of Oter Cape Cod Assoiation for the Preservation of Cape Cod / (((((( ])))))

2 ,,.l THE ERODNG SHORES OF OUTER CAPE Coo By Dr. Graham S. Giese Sientifi Advisor to APCC Researh Speialist, Woods Hole Oeanographi nstittion and Rahel B. Giese Conservation Athor llstrations by Patriia B. Morse The initial work from whih this blletin developed appeared as a series of artiles in the Cape Codder. Original Printing Otober 1974 Reprinted with permission of the athors, Janary 1994 nformational Blletin No.5 THE AssooATON FOR THE PRESERVATON OF CAPE CoD Box 636, Orleans, MA 2653 f{eprinting was made possible de to a grant from the Woods Hole Oeanographi lnsuttion Sea Grant Program (Grant No. NA9-AA-O-SG48, WHO Sea Grant projet No. E/R-13-PO), part of the National Oeani and Atmospheri Administration National Sea Grant College Program Offie, Department of Commere. The views expressed herein are those of the athors and do not neessarily reflet the views of NOAA or any of its sbagenies.

3 THE ERODNG SHORES OF OUTER CAPE COD Reminise a bit: a smmer visit to Trro's Coast Gard Beah, a town-owned beah jst north of Highland Light. There the liffs towered high behind the beah, providing good shelter from the prevailing offshore smmer winds whih blow from the sothwest, aross the ntinent to the sea. The bakshore of the beah (the flat pper beah above the reah of the tide) was broad as it sally is in smmer. The foreshore (the sloping front of the beah whih is alternately sbmerged and exposed by the waves and the tides) was steep. A gentle swell was ming in. The small waves broke lazily. against the steep foreshore, bt after breaking they sent a sdden rsh of foam and water (the swash) p the slope. The more tranqil retrn flow downslope (the bakwash) left the foreshore wet with water draining seaward. All the while, the sand of the foreshore was in motion. The waves, when they broke. distrbed the sand beneath them. This sand was lifted from the bottom, mixed with the trblent breakers, and arried p the foreshore by the swash, down the foreshore by the bakwash. And so it was last smmer and the smmer before. A ntinosly plsing movement of beah sand on the steep foreshore of a wide beah responding to the breaking of long low waves. The smmer visitor may think that eah year he finds the same wide sandy beahes lying at the foot of the same liffs, bt that is an illsion. Smmer is not forever, and beneath the plaid srfae of the smmer beah lie the sands of the starker sene of winter storms. For dring winter, the smmer mask of harmony between sea and land is dropped, and the eternal nflit of the elements resmes. Even dring that smmer visit sars of the winter ravages were visible on the bakshore of the beah and in the fae of the liff. The bakshore nsisted of two nearly horizontal terraes-or berms. The higher berm whih Jay jst in front of the liff was the so-:alled "stom berm." Among the driftwood on its srfae were hge ttmbers whth had been left by winter storm waves. And aross the fae of the liff was a faint. nearly horizontal line some fifteen feet above the storm berm. This marked the level to whih the liff had been wave t dring the preeding winter. Exept for the line, all evidene of the winter t was now hidden by the sand and gravel whih had slid down the slope from above. Severe winter storms are a fat of life for the New England ast. Over a seventy-five year period the Weather Brea at Boston reported 16 gales-that is, storms with ntinos winds over 32 miles per hor. Of those 16 gales, eighty blew from the northeast, and as a look at the map will verify, a northeast wind is onshore along the oter ast of Cape Cod and diretly onshore at Highland Light. l. Typial Smmer Beah Profile of Oter Cape Cod B.akshore--,-... Foreshore-., i EE ;em,:>m ll Nearshore Bar The slashed region represents the eroding shore fae of the glaial de posits of Cape Cod. The erosion is amplished hiefly by wave ation. The stippled region represents the beah and the nearshore sediments whih have been sorted ot from the glaial deposits by wave ation and whih are in the proess of being transported along the shore by the waves. 2.

4 The waves whih are formed by the northeasterly gales striking the oter Cape are hge and frios, bt before reahing the beah they break on the bars. the sbmerged sand ridges whih parallel the shoreline. Along the oter ast there are generally two lines of bars: the oter (offshore) bar whih lies several thosand feet from the shore and the inner (nearshore) bar whih is sally several hndred feet or less from the beah. Dring a gale the biggest waves break on the offshore bar. and thse breakers sometimes reah heights of twenty feet or more. Movmg shoreward over the deeper water between the oter and inner bars. the waves re-form and then, at the inner bar, break again. These inner breakers may be eight feet high. nshore of the inner bar the sea is a frothy nfsion of breakers tmbling together and roaring inessantly p the beah. Bease the strong onshore winds and low atmospheri pressre have raised the sea level, perhaps as mh as three feet above what it wold have been otherwise, the trblent srf reahes high onto the shore. These storm waves move the beah sands mh more rapidly and violently than did the mild smmer swells. The beah sand is t away and arried offshore by the trblene of the srf. Where dring smmer a steep foreshore rose to a high berm, in winter a low flat beah extends nhanged to the frthermost reah of the waves. Althogh the tide by itself is not responsible for the beah hanges, the rising and falling of the tide distribtes the erosive ation of the storm srf over a wide streth of beah. The height of the beah may be reded by as mh as ten feet at a single spot when a high tide brings the storm srf p the beah. Where one stood a lofty berm, one lowtide later may be fond a hard flat plane. Finally, after the protetive skin of beah sands is removed, the storm seas t away at the loose sands and gravels whih form the body of Cape Cod. The erosion of the oter arm of Cape Cod takes plae every winter. More some winters than others. More at one plae than another at any one time. Bt every winter storm waves t away at the Cape. "LANDSLDE ERODES CLFFS AT CAPE COD LGHT" annoned the Provinetown Advoate, September 21, The artile told of the loss of a two hndred sqare foot setion of the bakyard f the Coast Gard Cape Cod Light (Highland Light) Station, and the deposition of 1, bi feet of liff debris on th beah below the Light. Again in Deember and Janary other shdes orred and looking p from the beah, the fondations of a bilding ld be seen exposed in the fae ofthe liff. On Jly 6 and again on Otober 12, the Advoate reported spelation as to the possibility of the sea breaking throgh the greatly 3... diminished barrier dne at Ballston Beah in Trro and damaging the pper part of the fresh water marsh of the Pamet River. There followed offiial and noffiial meetings and disssions involving the Trro Seletmen, the Trro Conservation Commission, the National Seashore Sperintendent and erosion experts. Despite all the meetings and disssions, in Marh the Advoate reported that gale fore winds had driven a few waves over the dnes and road into the marsh. At Beah Point on the bayside of Trro, motel owners feared for -their bsinesses when fall storms sent breakers ponding against the blkheads only a few feet from their motels. The Advoate qoted one owner as saying his motel was "on the brink of disaster," and blldozers were kept bsy on the beah moving sand p against the blkheads. Voters at the Tr wn Meeting in Marh agreed to appropriate $1, as the town's share of the first phase of a groin nstrtion projet to hek the erosion. So it went that winter and so it has gone every winter. Jst how rapidly the erosion is proeeding is a qestion that has long been disssed. Thorea noted that at one plae opposite the Highland Light the liff had lost abot forty feet between Otober, 1849, and Jne of the following year. However, he "jdged that generally it wa not wearin.g away... at the rate of more than six feet annally" adding-what many fail to realize-that "any nlsion drawn from the observations of a few years, or one generation only, are likely to prove false... '' The first arefl determination of Cape Cod's east ast erosion rate was provided by the srveys of Henry Marindin of the U.S. Coast and Geodeti Srvey dring the period 1887 throgh Comparing his reslts with those of a srvey forty years earlier, Marindin estimated the rate of retreat of the liffs between Highland Light and Naset Light to have been 3.2 feet per year. A determination based on an even greater time span, seventy years, was provided by the srvey made in 1958 and 1959 by the Woods Hole Oeanographi nstittion's astal stdies grop headed by Dr. John M. Zeigler. Their reslts mpared with those of Marindin indiate an erosion rate of 2.6 feet per year for the same setion dring the period between the srveys. The differenes between the rates are notthe reslt of a redtion in the long term rates of erosion. Rather, the differenes reslt from the fat that althogh we make se of the nvenient measre ''annal rate of erosion,'' its se neals the reality that the liff erosion proeeds in jmps. At any one plae there will be little erosion for a long period of time followed by mh erosion over a short period of time. A strikingly lear demonstration of the erosion rate at a single loation is provided by the Cape Cod National Seashore's exhibit at the 4.

5 site of the former Marni station in Soth Wellfleet. There. at the edge of the liff where one stood the high antenna towers whih first sent telegrphi messages aross the Atlanti, is a small sign whih reads: At this point the sea has arved its way inland more than 17 feet sine Marni bilt his wireless station in 192." We do not wish to give the impression that oter Cape Cod's astal hanges are entirely erosive. The sea has bilt the entire end of the Cape west of High Head, North Trro, inlding all of Provinetown and part of Trro, as it has also bilt Naset Beah and Monomoy sland. These latter featres are examples of barrier beahes. Sh forms make possible the existene of salt marshes. (For a disssion of the high prodtivity and importane of salt marshes to the astal esystem, see APCC nformational Blletin Nmber 6, ''Cape Cod Salt Marshes''.) Bt the amont of land whih has been bilt is small mpared to the amont of land whih has been removed. Oter Cape. Cod is eroding. We have disssed primarily the erosion of the oean shore, bt the bay shore also is eroding althogh at a somewhat slower rate. We often hear the qestion: What an be done to ntrol the erosion? The nern is nderstandable. Poplation is inreasing. Land vale is inreasing. Bt the amont of land is dereasing. Well, what an be done? There are many temporary and partial answers of varying mplexity and pratiality, bt the single final answer is very simple: nothing. Nothing an be done to prevent the erosion ofthe shores of Cape Cod. To the person whose hose sits imperiled at the edge of the sea, this may be a distressing state of affairs. He is nlikely to realize that Cape Cod is merely a temporary deposit of glaial sediment, pasing briefly (in the geologial sense) on its way to inevitably being washed into the sea. Viewed broadly, astal erosion is a single bt important part of the basi earth proesses. Bt the sale and long time periods of these proesses make it diffilt to see shoreline erosion as a fndamental part of the evoltion of the earth's srfae. We see too little of the world for too short a period of time and as a reslt man is astomed to viewing erosion as prely destrtive, a feared misfortne. We speak of it as a wasting disease. The yle of earth dynamis that inldes erosion involves montan bilding, erosion, sediment transportation and deposition of sediment in the seas followed by renewed montain bilding. This ylial proess is as fndamental as the yle of evaporation and preipitation. The appearane of anient marine fossils embedded in the strata of montain tops is vivid evidene of the earth-sea ntinm. Bt to nderstand the dynami proesses that bring the remains of sea reatres to the tops of montains, let s begin below the sea floor. The earth s rst nsists of plates that move relative to eah other. 5.,,... Some move away from eah other forming seas; some are moving together forming montain ranges. Dring this montain bilding proess great mpressive fores fold, sqeeze and thrst the thik sediment apron whih makes p the astal plain and the ntinental shelf. As a reslt, the sediments derived both from the earth and the sea are pshed pwards. Earthqakes, falting and volanism are some of the atalysmi effets whih ampany montain bilding. Molten. rok rises from the depths of the earth's rst forming granites and lavas \l'hih mix with the plifting sediments and the whole is transformed into deep-rooted, high-peaked montains. This proess is today ntinin_g to form the Andes Montains of Soth Ameria. All the while, air, water and sn are ating together to wear the montains down and retrn them to the sea. The winds, in nstant motion generated by the heat of the sn, blow fine sediments from the montain sides. Winds blowing pon the srfae of the sea prode waves whih wear away the rgged astal margins of the land. The winds arry water vapor evaporated by the sn from the sea srfae over the land. There, as rain, it beats pon the montains and washes them, piee by piee, from rivlet to stream to river and finally to the sea. n some ases the water mes down pon the land as snow whih, when deep enogh, flows as glaiers. The glaiers qarry the earth rok and arry the piees along. When finally the glaiers melt, the rok piees-gravels, sand. md, and lay-are released either diretly into the sea or in land deposits whih are later arried to the sea. At the edge of the sea, waves and rrents redistribte those deposits into ribbons along the shores. As sea level rises and falls hndreds of feet over the millenia, the sea lays down blanket pon blanket of sediment along the edge of the ntinent. These sediment layers form a ntinos apron from the montains to the nderwater edge of the ntinent. The expanse from the foot of the montains to the seashore is alled the astal plain. The sbmerged land from the seashore to the ntinent s edge is the ntinental shelf. The loation of the shoreline, whih divides and nites the land and sea, depends pon the sea level at any given time. t is here that the major sea fores at pon the land. With the passage of hndreds of millions of years, the sediments whih form this apron beme miles thik and the yle resmes when montain bilding takes plae and these sediments re-emerge as lofty peaks. Or own astal plain and ntinental shelf extending along the entire east ast of North Ameria owes its existene to the Appalahian Montain Range. This mighty range rose into being abot 25 million years ago and there are indiations that peaks over three miles high were formed. Sine that time the Appalahians have ndergone erosion interspersed with minor renewed plift. Among the many types of erosion whih have slowly worn the 6.

6 Mayflower Heights Pilgrim Lake (East Harbor) >< High Head _ Coast Gard Beah (Trro) \..--- Highland Light (Cape Cod Light) N Ballston Beah ;--J w E Jeremy Point,.., Naset Light - s Atlanti Oean..... "'!D..... ::l z "' Cape Cod? ' / ', t:o"' a- t (:)tb, " " Monomoy sland

7 ' T... C:.,._ Cll: Cl) -.: 1::(/) :... - "' oa.. _L o6e sjeaa '9L anaj4s "' :... : ::l > "..... ' '.. '' "' Cl) E LO Cl) (/) +-' : N... : : - Cl) "' o : - tll) ro ro : ().. a.. "' Cl) E "". N : ro.- Q.) Cl) (.!) (/)... Cl) > ""C ro - tll) w z.. ::J en Appalahian rags into gently ronded hills were the spreading glaial ie sheets whih advaned and retreated over North Ameria dring the Pleistoene Epoh, whih began abot two and a half million years ago. Cape Cod owes its origin to the last ie advane, known as the Wisnsin Stage. This great glaial sheet first arved its way soth 5, to 7. years ago. Stalling here for several thosand years before a warming limate ased final retreat, the glaial lobes whih broght the material of whih Cape Cod is made nveyed their lode into deposits hndreds of feet high. _ Sine their deposition by the melt water streams from the glaial ie some 15, years ago. the temporary deposits forming Cape Cod have ntined their progress toward ltimate deposition in the sea and inrporation into the Atlanti astal plain and ntinental shelf system. The most signifiant erosional agent at work is the worldwide rise in sea level whih neessarily ampanies the retreat of ntinental glaiers. For it is at that very point where sea meets land, the shoreline, that most erosion takes plae. The position of the shoreline is determined by the sea level. That thin, inargable line has been reeping inland sine glaial retreat began. The rate of sea level rise at Cape Cod was abot 1 feet per 1, years following the Cape's deposition ntil abot 2, years ago. Sine that time the level of the sea has ntined to rise bt at abot one third of the former rate, a little more than 3 feet per 1, years. Althogh sh a rate may seen very slow, partilarly when regarded over sh a short period of time as a year, its importane bemes lear in view ofthe very slight inlination of the sediment layers making p the Atlanti astal plain and ntinental shelf system. The average slope of this ntinental border is approximately one vertial foot for eah 1, horizontal feet. This means for every foot the sea level rises (vertially), it wold spread 1, feet over the land (horizontally) if the inlining ntinental border were perfetly smooth withot islands, valleys, hills and other nfigrations sh as Cape Cod. At a sea level rise rate of 3 feet per 1, years, the sea wold be enroahing pon the land, if it were a smooth plain, at the rate of abot 3 horizontal feet per year. n fat, the enroahment of the sea has been so rapid sine the ie retreat that only dring the past several thosand years have the deposits been sffiiently sbmerged to prode a form that we wold regnize as Cape Cod. For example, 7, years ago Cape Cod, Martha's Vineyard, and Nantket were all part of the same land mass whih extended some 25 miles eastward from the present east ast of Nantket. Part of the fishing shoal whih is known as Georges Bank and whih lies 1 miles east of Cape Cod was then an island. And the sandy Provinelands Hook-Provinetown-had not yet begn its,growth otward from the glaial deposits of Trro whih end at High Head

8 The mehanism by whih shoreline forms are developed involves the breaking of waves along the shoreline. Sand is moved along the shore as the reslt of waves breaking obliqely to the ast. t is this wave ation that ants for most of the alongshore movement of beah sand (littoral drifting, in tehnial terms) and not tidal ation as is often spposed. The larger the waves and the greater the angle of attak, the more the sand is moved along the shore. As long as Georges Bank existed as an island it offered the oter Cape shores niderable protetion from the fry of the easterly and sotheasterly open oean waves. The littoral drifting was then prinipally from north to soth, Trro to Orleans. With the gradal sbmergene of Georges Bank de to rising sea level, this protetion diminished and the intensified waves angling in from the east and sotheast began moving material from Trro to the north and west. This hange began abot 6, years ago. The reation of the Provinelands Hook was nderway, its sbstane ming from the sorting ot of glaial material washed ot of the liffs of Trro. To the soth of Trro, however, the predominating diretion of littoral drifting remained sotherly and a rresponding bildp of sand orred to the soth, reslting in the formation of Naset Beah and Monomoy sland. The bayside was to feel the effets of the sbmergene of Georges Bank as well, for the growing Provinelands Hook now offered protetion from the northerly and northwesterly waves. Then, along the bayside shore of Trro, the diretion of littoral drifting beame soth to north. Sand washed along the inside rve of the Cape finally ame to rest in North Trro and formed the long sand spit known as Beah Point, while to the soth of bayside Trro sand was washed soth and deposited to form Jeremy Point off Wellfleet. Bt while these featres have been slowly growing, the parent body has been rapidly disappearing. As disssed earlier the oean shore liffs are retreating at a rate of2;6 feet per year. The bayshore liffs are also retreating at the lesser bt still signifiant rate of abot 1 foot per year. What of the ftre? Wbat will the Cape's fate be? William Morris Davis, Professor of Geology of Harvard and fonder of modern geomorphology, wrote in his stdy of the otline of Cape Cod, pblished in 1896: ''The Provinetown peninsla may be expeted to otlast the Trro mainland; for as long as the latter exists, the former mst reeive ntribtions from it. Bt when the mainland is washed away-ten thosand years hene, at the present rate of wearing-then Provineland mst rapidly disappear... All these hanges are rapid, as hanges go on the earth's srfae. The Trro mainland will soon be destroyed, and the sands of Provineland will be swept away as the oeani rtain falls on this little one-at geographial drama." 11. Jst as the earth's water is ntinally reyled throgh evaporation and rainfall, so it is with the land: the sands whih wash into the sea today will be a part of ftre montains. Althogh this is an apt analogy, we have diffilty in relating it to the matter of or eroding shores bease of the awesome sale of earth hanges. Unmindfl of the ylial proesses of earth dynamis (montain bilding, erosion, sediment deposition in the seas followed by plift and montain bilding) we single ot and think of erosion as a alamity, addressing orselves to "the erosion problem." At least sine the time of Moses we have thoght of the land as "ors." The Book of Genesis bids "... let them have dominion over...all the earth... fill the earth and sbde it." Failre to protet "or" land from the enroahment of the seas nstitted neglet of sriptral dty. Man's obvios sesses at stabilizing river banks (for example, Rome's Tiber, Paris' Seine and London's Thames) have led him to believe that oean shores ran be stabilized in a similar way. Bt, despite the millions of dollars spent annally in the United States sine the Send World War on attempts at beah erosion ntrol, we have only seeded in mponding and inreasing ''the erosion problem.'' The Panel on Oeanography established nder President Johnson reported: ''The Panel was distressed to find a high failre rate of nstrtion projets in the srf zone and on beahes." The report goes on to desribe the destrtion of beahes by strtres designed to protet or extend them and varios other follies mmitted at the expense of the taxpayer. A stdy of Cape Cod's oean shores by the Army Corps of Engineers began in 1973 when fnds were athorized for an erosion ntrol stdy of the oter arm of Cape Cod extending from Provinetown to the sothern extremity of Naset Beah. The stdy, mpleted in 1979, finally nlded that, for enomi and environmental reasons, "no beah erosion ntrol projet be adopted by the United States for providing protetion against erosion and storm damage along the easterly shore of Cape Cod.'' Let s take a brief look at some of the ways man has already affeted the shores of Cape Cod, either by intentional effort at ntrol or throgh nintended distrbane of natral shoreline balane. An attempt to ntrol shoreline hanges of the oean shores of Cape Cod was ndertaken by the Cape Cod National Seashore in 1966 at Eastham's Coast Gard Beah in an effort to protet the aess road to a new parking lot. Winter storms, espeially those in , had swallowed p mh of the ten foot liff on whih were sitated the vestiges of a town-bilt parking lot and the aess road. n a desperate attempt to hold the bank and thereby preserve the aess road, 3, bi yards of rbble nsisting largely of hge hnks of broken nrete were dmped over the bank and onto the beah. 12.

9 The prinipal effet of this ation has been the aestheti defilement f this beah. n 1973, the then Seashore Sperintendent, Leslie Arnberger, smmed p the reslts by saying, "We may have gained a few years, bt in trn a hazardos and nsightly sitation has reslted." Mr. Amberger's previosly stated position of "learning to live with erosion as a fat of life" has beme the aepted poliy of the National Park Servie. t was annoned in September 1973 that the National Park Servie wold no longer try to ntrol shoreline proesses anywhere along the astline within its jrisdition. This poliy ame as the reslt of detailed sientifi stdies mbined with a history of stly failre at ntrolling eroding shorelines. Seeding Seashore Sperintendent, Lawrene C. Hadley, said at that time, "We have reahed the nlsion that what we have been doing is not the way to go at all. t is time to set ot on a different rse that wold allow those astal landsapes to shift with the natral fores." The threat to man-made strtres sh as parking lots and lighthoses sally provides dramati witness to erosive fores at work. n the ase of Ballston Beah at the head of Trro's Pamet River, striking evidene of the sea's advane pon the land was given in the winters of 1972 and 1978 dring severe easterly storms. Waves washed over the dwindling barrier dne onto the paved road nneting North and Soth Pamet Roads and threatened the fresh waters of Pamet River. This has happened before and one sh washover in 1896 led the Provinetown Advoate to predit that the oter Cape wold one day "be made an island." n November of 1933 Boston Globe headlines portended 'Cape Cod an sland Ten Years from Now.'' Under the inept headline the sbheading followed, "sea threatens to break aross Pamet River nless Unle Sam intervenes." Bt Man's nintentional intervention was already too great. The advent of the atomobile had led to the stabilization by hard-srfaing, and later paving, of this road rnning behind the barrier dne. The shoreline here is natrally reeding inland. Left to its normal movement, the dne wold have migrated inland, all the while maintaining its size and form. The road wold have likewise moved inland, always rnning between the foot of the dne and the head of the Pamet. One paved, the road was fixed, bt the dne was not and its enroahments pon the road were neessarily removed. Ths th_e sstenane, natral movement and protetive qalities of this barrier dne were pset. As a reslt, this important natral protetion has deteriorated and washovers or with greater freqeny. The bayside of the Oter Cape has a longer history of attempts at maniplating natral shoreline proesses. The ses of the rivers, harbors, beahes, marshes, flats, and other featres have been manifold. Man's interest in their ndition has always been keen, ever sine the Pamet and Naset ndians fished and farmed this region. 13. Left alone, of rse, these featres take are of themselves and adjst to the natral fores ating pon them. Certain forms evolve in response to the fores of winds, waves and rrents and exist in a state of eqilibrim ntil the fores hange. A new balane is then ahieved. Tampering with any of the elements in this balane of fores is bond to have troblesome effets. To keep the moth of Pamet River a viable harbor, rok jetties extending ot into the bay were bilt in At first this appeared to be a sessfl ventre. Bt these jetties interrpted the normal flow of sand along the shore from soth to north. Ths, the sand amlated behind the soth jetty, starving the beahes on the north side and eventally spilling arond the jetty's end and into the river hannel that the jetty was bilt to protet. Keeping the hannel open now reqires periodi dredging. Withot the jetties, Pamet River wold have maintained an opening!tself as it had done throgh the ages. Throgh natral proesses, the mlet wold migrate from soth to north. One reahing the northern extremity of the river valley a new opening wold break throgh at the sothern end. This rerring pattern of inlet migration in the diretion of littoral drifting is mmon to estaries. Bt the vagaries of loation and depth ofthe natral Pamet inlet did not sit man's pratial sense. Another example of the nhappy reslts of man's interferene in natral shoreline proesses is orring in Trro. Bease of the heek-by-jowl mmerial development of North Trro's Beah Point, the shoreline hanges taking plae there are the ase of extremes of feeling among the property owners. Beah Point, as desribed earlier, was a growing sand spit sheltering behind it a tranqil harbor whih mariners for entries sed as a refge from storms and a resting plae. '! beame known as East Harbor and is still alled that by some althogh sme 1869 it has been a lake-pilgrim Lake.. The dending of the_ land by the early settlers led to the gradal filhng of East Harbor w1th blown sand. To qote Kittredge's "Cape Cod: ts People and Their History," pblished by Hoghton Mifflin Company. the sand "washed down throgh its (East Harbor's) entrane into Provinetown Harbor whih was being gradally silted p by this nstant deposit." To halt the flow of sand into Provinetown Harbor, a dike was bilt joining the end of Beah Point to Provinetown at Mayflower Heights. The dike was mpleted in Te bilding of this dike, for however good reasons, broght m1sh1ef to the balane of fores. As stated earlier, shoreline forms hane i_n response to hanged fores ating on them. Tidal flow srgmg m and ot of the moth of East Harbor had interrpted the alongshore rrents and inflened wave ation on the shore. The losing of the harbor entrane ended that tidal effet on the area and. made the shoreline ntinos. t also left a navity in the shoreline at that point. The response of the beah to the new nditions has been to 14.

10 form a lean reglar rve. This natral smoothing ot of the shoreline is today being proded by a filling of the navity with material eroded from the sotheastern portion of Beah Point. To the glee of the property owners to the north, their shoreline is bilding ot at the rate of 6 to lo feet per year, while to the distress of their brethren to the soth, the beahes are disappearing and ttages and motels are threatened. The nstrtion of sbstantial bildings on a frail and very mobile sand spit sh as Beah Point seems almost nbelievable in hindsight. The history of development was insidios: dike, road, little ttages, big ttages, little motels, big motels. To arrest the erosion presently taking plae and thereby protet the heavy private investment made there, town monies were alloated in 1973 for the nstrtion of two groins at Beah Point. f these groins were nstrted they wold prevent the establishment of eqilibrim nditions along this setion of the shoreline. By preventing hange in one setion of the evolving shoreline the entire shoreline wold be thrown inreasingly ot of eqilibrim. This defiane of natral order wold reslt in the "proteted" setion reqiring inreasingly greater mmitments to be maintained. Therefore, the nstrtion of groins along Beah Point wold be merely another link in the brdensome hain of astal problems and misfortnes initiated by or nwitting forebears when they stripped the land of vegetation over 2 years ago. EPLOGUE Cape Cod is a temporary, steadily diminishing glaial deposit whose shores have been sbjet to sbmergene by a rising sea level sine its reation some 15, years ago. Nothing that man an ever do, intentionally or nintentionally, will hange the fat that Cape Cod is slowly sbmerging. The erosion of or shores is bt a tiny part of the great yle of earth dynamis. Many generations will live here and there is plenty of room.and time, if we make wise se of or resores, to fill or needs for life here. Bt let s make no mistake; the shoreline annot be adjsted to sit short term needs withot affeting the lives of others, often for a long time. Costly and often ftile shoreline ntrol efforts are made to protet nwisely plaed roads and bildings. t wold make greater sense to bild arding to the nditions imposed by natre-adjst orselves to the hanging shoreline rather than trying to adjst 'ih shoreline to orselves. What we have to enjoy is the magnifiene of ever hanging natral shoreline forms: towering liffs, long sweeping beahes, reahes that hange from hor to hor with the hanging tides and winds. New forms will be born of the old and will themselves generate hange within the deliate balane offores. As part of natre's ntinm it behooves s to live within it harmoniosly. AFTERWORD This booklet was first pblished by the Assoiation for the Preservation of Cape Cod in Otober, 1974, and some minor hanges were made in the text in the late 197s. Despite the many developments that have orred in astal siene and astal management over the intervening years, it is re-issed in its original form bease we believe that the essential message it presents is as valid now as it was then. Graham Giese Rahel Brown