Scarborough Castle Trial Trenching

Geotechnical Investigation


Yorkshire Water Services Ltd


Geotechnical Investigation

Trial Trenching

Monitoring excavations on small construction sites is routine work for archaeological contractors. Being small, such jobs rarely command much publicity, but the results can nonetheless add important information to our archaeological knowledge. Geotechnical investigations, for example, typically by test-pitting or digging boreholes, take place prior to most developments. Before excavating a borehole with machinery, it is normal practice to first hand-dig a starter pit to determine the presence of any shallow obstructions or potential hazards such as live services. In archaeologically sensitive areas, this work is often carried out by archaeologists, as with the project described here.

In 2011, NAA was commissioned to monitor borehole investigations by Yorkshire Water in the Scarborough area. Four boreholes were sited in Scarborough Castle, and in accordance with the Scheduled Monument Consent for the work, NAA archaeologically hand-excavated a 2m x 2m starter pit at each location.

Scarborough Castle stands on a headland overlooking the North Sea. The headland was the site of a Late Roman fortified signal station, part of a chain of installations along the Yorkshire coast to watch for seaborne invasion. The main medieval castle fortifications and buildings stretched across the neck of the headland and were separated from the town by a substantial ditch now known as Castle Dykes. Although the castle fell into disrepair in the 15th and 16th centuries, its military significance remained, and it was besieged during the Pilgrimage of Grace in 1536. During the English Civil War (1642-51), Scarborough was the only port in northern England in Royalist hands, and this provoked a siege between February and July 1645. The Parliamentarian army set up a gun battery at St Mary’s Church and bombarded the castle entrance, partly destroying the castle keep. The Royalist garrison eventually surrendered through illness, starvation and a lack of ammunition. In 1653, during the Commonwealth, a permanent garrison was installed in the castle, which remained until 1878, after which time reservists continued to train there. The barracks were destroyed in 1914 by a bombardment of the town and castle by the German navy. 

The borehole investigations in 2011 recovered a fascinating range of material, some of which could be related back to the castle’s turbulent history.

The earliest find was a buried soil layer, which contained an assemblage of residual worked flints ranging in date from the Early Mesolithic through to the Iron Age. There were also numerous hand-built pottery sherds of probable Iron Age date and part of a jet bracelet of likely Roman date.

A second trench, sited within the north-west end of the Castle Dykes ditch closest to the castle gateway, revealed a series of post-medieval ditch-fills, indicating cleaning-out of the medieval ditch probably at the time of the Civil War siege. Supporting this premise, a stone cannonball was found in the base of the ditch, perhaps fired from the battery at St Mary’s and rebounding from the castle wall into the ditch.

The third trench uncovered the remains of a revetted bank built with re-used medieval stonework. Finds of early post-medieval pottery and clay tobacco pipes suggested that the bank may have been associated with the 17th-century military barracks.

The final trench, at the south-eastern end of the Castle Dykes ditch, recorded a sequence of 20th- century silting events and two modern pits.

Despite the small scale of NAA’s ‘keyhole’ excavations at Scarborough Castle, the results show that small interventions such as these can add detail to the understanding of a site. The evidence found showed that the headland had been used by people over the past 10,000 years, from the early prehistoric through to modern times. Previously, evidence for prehistoric activity had been found by excavations near the cliff edge, but the new work has shown that this extends over a significantly wide zone. The Roman finds support the idea that the signal station may have been accompanied by a small civilian settlement, which would have extended beyond the fortifications. For later eras, the find of the cannonball adds substance and interest to often dry accounts of historical events. 

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