The Project

Why is the Gay Head Lighthouse being moved ?

The Lighthouse now stands approximately 46 feet from the edge of the Cliffs and within two years, at current erosion rates, it will be too close to the edge to move safely. Erosion has been observed for years so the Martha’s Vineyard Museum commissioned an erosion study in 2010. Based on that study, it was determined that something would need to be done within 10 years. It was only after consultation with engineers that it was discovered they would need at least 30, preferably 40′ in diameter around the light to move it safely, hence the URGENCY.

Who owns the Gay Head Lighthouse?

At present, the U.S. Coast Guard owns the lighthouse but it was listed as surplus property on August 1, 2013 and the town of Aquinnah has submitted an extensive application for ownership. The application is in process with the National Park Service. The Town of Aquinnah is the sole applicant. Government review, which involves three federal agencies (National Park Service/Dept of the Interior, US Coast Guard and General Services Administration), is expected to take several months. After transfer of ownership, the United States Coast Guard will continue to oversee the actual light to assure it fulfills its navigational purposes.

Will The Gay Head Lighthouse still be a functioning navigational device?

Yes! It remains a vital aid to mariners and we hope to keep the white, red sweep going for many years to come.

Will the Lighthouse be open to the public?

Yes.

When was it built?

The current brick structure was built in 1854, replacing the original wooden structure built in 1799. The beacon was installed and lit for the first time in 1856.

How much does it weigh?

Approximately 400 tons!

Where will it be moved?

The relocation site was selected in July 2014. The Gay Head Lighthouse will be relocated 150’ to the east/southeast of its current location onto town owned land (lot 23). This site was favored for many reasons:  elevation and position similar to its current orientation with its surroundings at the Aquinnah Circle; geotechnical soil tests indicate better load bearing subsoil characteristics at this location; meets navigational purposes in both elevation and position and maintains “day mark” or visibility from the water from all vantage points; and core samples analysis indicating a stable geographic formation which should remain resistant to future erosion for a minimum of 140 years, according to an analysis of historic erosion rates. This site was also preferred by the National Park Service, the Wampanoag Tribe and the Massachusetts Historical Commission due to a combination of more favorable ecological and archeological considerations.

How much will it cost to move the Light?

Costs are dependent upon the site chosen but will approximate $3,000,000. which includes all aspects of the project including engineering, geotechnical testing, property acquisition, pre-move engineering and reinforcement, site prep, moving of the structure, restoration of the original site and move path, landscaping, creation of a new access pathway, and final renovation of the structure.

Where will the money come from?

Fundraising is well underway with support coming from hundreds of individuals, private and public foundations, events, and Community Preservation Act funding approved by voters in all towns on the island.

Can the lighthouse be moved, and who is moving it?

Yes the lighthouse can be moved and an expert lighthouse mover has been hired for the job. The Town of Aquinnah has contracted with International Chimney Corporation for the relocation of the Gay Head Lighthouse. They bring extensive knowledge and expertise to the table. They have moved several lighthouses including Cape Hatteras Light, a Block Island light and Gay Head’s sister brick masonry lighthouse on Nantucket, the Sankaty Light.

When will it be moved and how long will it take?

If all goes according to plan, the Lighthouse will be moved in the spring of 2015. It should take approximately days for the move. Restoration and landscaping will take longer.

Why is the Town of Aquinnah involved in saving the Lighthouse?

The Gay Head Light is undoubtedly the most recognized structure in Aquinnah. Though it has long served as a beacon to mariners, its light is a deep and satisfying comfort to residents and visitors alike, who treasure it for what it is and what it represents. It’s up to all of us to help to preserve it.

 

Anyone visiting the Gay Head Cliffs and Lighthouse can see how close the lighthouse is to the cliff-edge and how erosion threatens the Gay Head Lighthouse. Geological and engineering studies of the threatening situation were done in 2012. See below:

Gay Head Lighthouse Site Assessment
Aquinnah, Massachusetts
December 2012

Patrick Williams

Synopsis

Geological and engineering evaluations of landsliding at the site of the Gay Head Lighthouse were initiated in summer 2012.  A survey (monitoring) array was established and a new survey of the bluff edge was completed.  Historical data have been developed to show bluff retreat at an average rate of up to 1.8 feet per year during the period from 1870 to 2012. The general context of landsliding at the Gay Head Cliffs indicates that groundwater flows towards the cliffs, and likely accelerates sliding. Draining standing water (i.e. vernal pools and wetlands) to surface streams might diminish rates of land-sliding. For planning purposes, historical evidence indicates that moving the light to a location 180 feet farther from the bluff could be expected to protect the Gay Head Lighthouse for several generations.

Introduction

This report presents our progress in site evaluation, assembly of historical evidence, and establishment of survey monitoring for the Gay Head Lighthouse (GHL). The studies and activities summarized here are conducted by Patrick Williams (Williams Associates) and George Sourati (Sourati Engineering Group). The studies are directed to provide a sound basis to evaluate relocation alternatives for the GHL, particularly to support evaluation and monitoring of current and future site stability for the existing location and relocation alternatives.  While we endeavor to provide and update the best available information on the present and future condition of lands surrounding the GHL, uncertainty and variability of natural processes are a given, and future influences cannot be known absolutely. Long-term average behavior presented here does not account for changing conditions of climate and weather events that during a given period may slow or speed mass wasting (landslide) processes in the immediate area of GHL.

Site context

Landslide activity is the primary agent of erosion at Gay Head Cliffs.  The principal form of landsliding is “rotational slumping”, i.e. sliding surfaces are nearly flat in the lower portions of slides, but steepen gradually to nearly-vertical in the upper portion.  Landsliding at Gay Head Cliffs is aided by several factors, principally high – steep topography, weakly consolidated sedimentary materials, and the action of waves removing material from the foot of the sliding mass. A substantial further effect, and probably the only effect with potential for human intervention, involves groundwater flow.  Groundwater of the cliff area moves generally westward, towards the cliffs,  moving through sand and fractures. Fluid pressure weakens shears, and adds moderately to the weight of the sliding material.  If any one of these features (topography, low strength, wave erosion, the effect of  water) was not present, the rate of sliding at the cliffs would likely be diminished.

The body of the Gay Head Cliffs is composed primarily of late Cretaceous (older than 65 million years) shallow-water marine deposits such as beach, estuary, marsh and lagoon. The materials are principally semi-consolidated clays and sands with some gravel. Equivalent deposits are present on the continental shelf from Maine to New Jersey.  Sand intervals in the beds form local aquifers. The largest natural exposure of these ancient coastal deposits is that of Aquinnah’s Gay Head Cliffs.  Claystone, sandstone, and (organic) lignite comprise the cliffs.  Uplift, folding and faulting of the cliffs was caused by snowplow-like “ice-push” at the southern edge of recent glaciation. Hills and ridges of the larger up-island area were formed by the push, and many are cored by materials similar to those found at the cliffs.

Site evaluation

Landslide features of the lighthouse area were inspected on site and remotely using aerial photography and cross-section and measurement tools available within the mapping program Google Earth Pro (GEP).  The distance from the lighthouse to bluff edge was measured in the field to be approximately 50 feet.  The bluff edge is expressed by near-vertical drops of up to 10 feet, with subsequent steps and drops extending down slope. The bluff edges are scalloped by concave features, consistent with landslide head scarps[1].

Historical rate of bluff retreat

The original lighthouse tower at Gay Head was constructed in 1799. In 1844 contractor John Mayhew moved the structure 75 feet southward and away from the bluff edge. If the second location was approximately as far from the bluff edge as the original location, the 75-foot move and the 45-year time span indicate an approximation of the speed of bluff retreat: 1.7 feet/yr. Surprisingly this rate compares well with long-term rates evaluated from other evidence.  Other survey data are referred to in Island planning documents, which might provide long-term retreat rates. The 1989 Martha’s Vineyard Commission (MVC) Decision of Critical Planning Concern (DCPC)[2] for the Gay Head Cliffs cites a general bluff retreat rate of 2.5 feet/yr for the period spanning 1845 to 1979 (MA Coast Survey, 1985; Kaye 1973). The subjects of both of these sources are coastline change, not bluff retreat, and we have thus far not reviewed the original materials to verify whether the 2.5 ft/yr rate actually refers to bluff retreat or in fact refers to coastline change.

 

Town property maps dated 1870 and 1990(?)  illustrate the location of the bluff edge.  The 1870 document describes the approximately square parcel “46,” labeled U.S.L.H.E. (United States Lighthouse Establishment  – former name of  United States Lighthouse Service) (Figure 2).  On the 1870 parcel map, dimensions of the lot are approximately 300 feet square with bounds running about north and east. The north dimension is labeled 296 feet on the current parcel map.  Dimensions of the modern parcel map for lots #22 [CK2]and adjoining lot #23 are essentially identical to those of lots 47 and 46 from the 1870 map, with the major exception being where land evidently was lost to erosion. The modern southern boundary of lot 22 , [CK3]however, was measured as 178 feet (in 1990(?)), this is diminished from an original measurement of about 330 feet to the bluff edge (Figure 1), indicating a loss due to land sliding and bluff retreat of 152ft (Figure 1).  The north bound is measured at 82’ on the current parcel map, and is diminished from (approx.) 340 feet in 1870, a loss of 258 feet. Bluff retreat between the two maps can be evaluated by comparing the two maps, and examples are presented graphically in Figure 2.

Survey of lighthouse grounds

To establish present location of the bluff edge and to monitor future changes to the site as new ground failure encroaches on the lighthouse, 167 survey points were recorded between the light[CK4] and the bluff by Sourati Engineering Group (SEG) in August 2012 (Figure 3).  Fourteen temporary monuments were placed, and 8 “permanent” features such as fence posts, existing monuments and found features were documented.  The bluff edge was defined by nearly 100 laser survey measurements. Additional features located are the edge of the lighthouse clearing and the location of trails. Future surveys will encompass local permanent bounds markers to tie the array and surveyed features to the town plat map and to parcel surveys.  Note that the closest distance [CK5]to the bluff edge at the time of 2012 survey are 47’, 53’, 55’ and 55’.

 Rate of bluff retreat

The 2012 SEG bluff-edge survey has been compared to the 1870 bluff edge by hand fitting of the two maps with a Google Earth template (Figure 4). Reference marks for the fitting include house locations, fence lines,surveyed references (trails, clearing, fence, and the light itself).  With these aids, the 1870 bluff edge is believed to be located within an accuracy of about 10 feet, and the 2012 survey to within 5 feet (in the GEP visualization). In representative locations the bluff has suffered retreat of 175 feet and 260 feet.  This indicates an average rate of bluff retreat of up to 1.8 feet-per-year during the latest 142 year [CK6]period.

 

Continuation studies

This study is planned to continue through December 2014.  The scope of the current study includes repeating and evaluating the land survey annually, continuing to gather and evaluate historical documentation, and applying existing airborne laser scanning data to map landslide structures to better evaluate the rate and style of mass wasting. Each of these tasks will improve and support the [CK8]preliminary results summarized here.

Significant additional tasks for consideration include providing more detailed prognosis and site engineering for candidate relocation sites, and developing a proposal for groundwater mitigation.

References

Kaye, C. A., Map Showing Changes in Shoreline of Martha’s Vineyard, Massachusetts, During the Past 200 Years, with text, USGS Miscellaneous Field Studies Map: MF-534 Department of the Interior, U.S. Geological Survey.*

Long, J. P., The Gay Head Landslides, Martha’s Vineyard, Massachusetts, Causes and Remedies, Doctor of Philosophy Dissertation, University of Connecticut, 1971.

Martha’s Vineyard Commission: Decision of the MVC Designating Gay Head Cliffs as a District of Critical Planning Concern MAY 4 1989.http://www.mvcommission.org/doc.php/DCPC%20Decision%20Gay%20Head%20Cliffs.pdf?id=292(7).

Massachusetts Shoreline Change Project, Executive Office of Environmental Affairs, Massachusetts Coastal Zone Management Office, Shoreline Change Map, University of Maryland Coastal Mapping Group, 1985. *

Richardson, J. , The Gay Head Lighthouse and its geologic future (Houston, we have a problem). Report to Martha’s Vineyard Museum, May 10, 2010.

Van Westen , C. J., Geo-Information tools for Landslide Risk Assessment. An overview of recent developments, International Institute for Geo-Information Science and Earth Observation (ITC), Enschede, The Netherlands.

Trapped Groundwater Hastens Erosion at Gay Head Cliffs _ The Vineyard Gazette – Martha’s Vineyard News

---

[1] A head scarp represents a fracture produced by the calving away of a slide block from an intact body of earth.

[2] Martha’s Vineyard Commission: Decision of the MVC Designating Gay Head Cliffs as a District of Critical Planning Concern MAY 4 1989. http://www.mvcommission.org/doc.php/DCPC%20Decision%20Gay%20Head%20Cliffs.pdf?id=292

“A further study of the District (7) documents that seepage facilitates landslides along the west-facing cliff, as the bulk of groundwater seepage travels westward. The landslides of the Cliff area have a yearly cyclic rhythm with a small displacement during summer and early fall, very rapid rate during winter and early spring, and a slowing period in late spring. A correlation exists between rates of slide movement and infiltration. The study concludes that groundwater seepage is probably a major cause for landsliding.

Cliff erosion averaged 2.5 feet per year from 1845-1979 (8). This erosion results from landsliding, rainwash and wave erosion, with landsliding described as the most important process contributing to the erosion. Landsliding “begins by a vertical crack forming parallel to the Cliff and back from the edge by distances as great as 100 feet but generally less than 20 feet”. The strip of land bounded by the crack begins to drop vertically as much as 15 feet in a few months, eventually pushing masses of clay onto the beach and vulnerable to wave action (9).”

* (original material not yet located).[jtab/]

Technical Advisors :: Principal Local Advisor – Kent Healey, Ph.D Geotechnical Engineering, MIT

Consulting Hydrologist – Patrick Williams
Principal Geologist at Williams Assoc. San Diego, CA
Degrees: Cal Tech and Columbia Univ.

Consulting Geologist – Byron Stone, Ph.D
Research Geologist – U.S. Dept. of Interior Office of U.S. Geologic Survey
Head Geologist in Charge of Mass Quaternary Geology Project

Consulting Civil /Structural Engineer and Surveyor – George Sourati
Principal of Sourati Engineering
Vineyard Haven, MA

Consulting Landscape Architect – Michael Van Valkenburgh
Principal MVV Assoc.
American Academy of Arts & Sciences Fellow

Public Relations Strategist – Maura FitzGerald
Founder/Partner, Version 2.0 Communications
Boston, MA

 

Click image to see larger version