Bosiliack Excavation 2011: a summary
In September 2011 archaeological excavations were undertaken by Historic Environment Projects, Cornwall Council and the Cornwall
Archaeological Society at the Bronze Age settlement and field system at Bosiliack, near Lanyon Farm.
The excavations gave an exciting opportunity to provide training in archaeological techniques for members of the Society and to obtain
further information about the prehistoric occupation of the settlement. Despite being one of the most extensive and best preserved
roundhouse settlements in Penwith, since the 1980s, the site has been covered by dense vegetation, most notably bracken, and the
project therefore offered an important chance to examine the effects of rhizomes upon the roundhouse and buried archaeological
layers within the field system.
Fig 1 Counting Rhizomes.
The project involved the investigation of a small roundhouse which lies on the northern
side of the main Bronze Age settlement, and the excavation of test pits within the
prehistoric field system.
Eight 1m square were excavated at 10m intervals along a north-south transect through
the field system. The rhizomes within each of the test pits were measured (Fig. 1) and the
sections of each of the test pits were drawn, so that it could be established whether the
rhizomes were having an impact on buried archaeology.
Fig 2 Bracken Rhizomes in test pit.
Initial study of the results from the test pits suggests that an average length of 70m of
rhizome was present within a single 1m square test pit (Fig 2) and that most of the
rhizomes were above the level of the natural subsoil. The potential impact of rhizome
damage on buried archaeological deposits and structures was therefore found to be
Roundhouse 3 was targeted for excavation because it was immediately adjacent to the
field walls on the western side of the settlement and thereby provided an opportunity to
investigate the relationship between a roundhouse and the field system. The roundhouse
had become entirely concealed beneath a swathe of vegetation (Fig. 3) and before
excavation could commence this had to be removed and the bracken recorded.
Fig 3. House Three before excavation
However, the task proved worthwhile as a superb structure was uncovered. Roundhouse
3 was found to be approximately 6m in diameter with a south facing doorway, which was
located over a large slab of granite that may have acted as area of hard standing outside
the entrance. The walling of the house was not excavated; however, cleaning of the wall
revealed that it was double-skinned with large granite blocks holding a core of smaller
stones in place. Within the interior of the building, tumble from the wall was found
beneath a mat of rhizomes. Much of this disturbance is likely to have occurred in the last
couple of centuries, as slates were found inside the roundhouse and one of the adjacent
stones within the field wall had been split and one of them drilled, in order to make a
mellior stone for a horse whim. However, some patches of the original floor level
survived within the roundhouse and a few undecorated sherds of prehistoric pottery of
probable Bronze Age date were recovered from it. This layer was also sampled and it is
hoped that radiocarbon dates can be obtained.
Fig 4 Roundhouse 3 fully excavated.
Investigation of the adjacent field walls revealed that they ended just short of the
roundhouse. This suggests that they are either contemporary with the roundhouse, or
were built a little later and respected the wall of the upstanding roundhouse.
Fig 5 Open Day
An open day was held on Saturday 10th of September (Fig. 5). This was a great
success; over the course of the day over 100 members of the public visited the
excavations, and many discovered for the first time just how impressive the Bosiliack
At the end of the excavations the interior of the roundhouse was backfilled (Fig. 6) but
the walls left exposed. CASPN has added the site to its programme of monthly clear
ups, so that members of the public can now visit the roundhouse.
Fig 6 Roundhouse 3 backfilled.
Thanks to everyone who volunteered and supervised on site and to the guides who
helped with the open day.
Andy M Jones
© 2013, Cornwall Archaeological Society
Registered Charity 1055654
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