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Project Summary

Controversy has raged for many years over the origin of the underwater structure known as Spittals, which is situated on the South side of Filey Brigg. Scholars are divided between those that believe it is a natural formation and those that are convinced it is man made. 

The Filey Brigg project team undertook the task of trying to settle the matter. They first obtained advice from the Nautical Archaeology Society and then received instruction in Underwater Archaeological techniques, obtaining the NAS part 2 qualification.


Photo showing Spittals to the right (main part of Filey Brigg to the left) 

The possible origins for the structure were listed :


  • Glacial moraine
  • Tidal accumulation of boulders
  • Boulders washed from North of the Brigg in extreme weather
  • Original Coastline before erosion of glacial till


  • Natural formation built upon to create pier
  • Roman Harbour
  • Medieval Harbour or pier

Datum Line Established

During the Summer of 1997 a pre-disturbance survey of the site was conducted. A datum line was established at the landward/rock interface along the length of the structure. The line was marked at 20 metre intervals with numbered datum markings. A second baseline was established on the Brigg itself. 

The angle of the structure was measured from various positions and it was found in general that  it rose from the seabed at approximately 30 degrees. 

baseline.jpg (30453 bytes)

Click on above image to see diagram of baseline

Photographic Survey

The underwater visibility was poor, however an extensive series of pictures were taken of a transverse  section of the structure at each datum point. 

The structure is very uniform along its entire length and the rocks size showed no marked difference at any particular height. The average rock size falls within the range 400 to 500 mm. 

Geological Survey

Using the datum marks stone samples were collected along each transit line. The samples were taken at random and consisted of a mixture of small pebbles and shards chiseled off  the larger boulders. Identification of the samples was made by a professional geologist. 

83% of all rocks sampled were of local origin. The remaining 17% consisted of glacial erratics. The glacial erratics occurred within the pebble samples, whilst virtually all the shards were of local stone. . 

 Sonar Survey

A specially equipped survey vessel undertook a sonar survey using both side scan and a fixed depth sounding sonar. The resultant data was professionally processed into accurate charts. The chart reveals a second smaller structure to the east of Spittals.

bathymetry.gif (30794 bytes)

Click on above image to see chart of Spittals


Examination of the chart from the sonar survey reveals details of a structure that we propound as being that of a harbour. The positioning is in keeping with other harbours on this coast and would have given excellent protection from the tide and sea, before ancient quarrying activities removed much of the Brigg.

Placed in the location of the Spittals such a harbour would also have had the advantage of not drying out at low tide.

The geological survey rules out the possibility that the structure is a glacial moraine. The photographic survey shows the uniformity of rock sizes and that no rock sizes were larger than could be handled by men

Due to protection afforded by Filey Bay, the likelihood of the structure being a tidal collection of boulders is negligible. The rock sizes are too uniform to support the theory that rocks were washed over the brigg and channeled into a line by its shape.

If the structure was the remains of the ancient coastline before the erosion of the clay, it too would have been eroded and would not have remained the massive structure it is today