2016:054 - N5 Ballaghaderreen-Scramoge Road Development, Kilvoy, Cloonyeffer, Cartronagor, Creeve, Gortnacrannagh, Killeen East, Lavally/Vesnoy, Bumlin, Killdalloge and Shankill, Roscommon

A note on ITM Coordinates for this licence.

Pit 1—581062.989,787607.960 (is used as the main map locator for this site)

Other ITM coordinates: Pit 2 581054.865,787561.104

Pit 3 580475.670,787516.829

Pit 4 580486.587,787522.272

Pit 5 580519.620,787527.768

Pit 6 593939.152,782032.952

Pit 7 594203.762,781716.175

Pit 8 594389.519,781465.962

Pit 9 594334.61,781584.4120

Pit 10 594346.684,781565.505

Description

A combined geophysical (15R0123) and geoarchaeological (15E0438) investigation commissioned by Roscommon County Council and funded by Transport Infrastructure Ireland, was conducted at 10 pits within 5 pitfields on the proposed N5 Ballaghaderreen-Scramoge road development; County Roscommon as part of the EIS phase of the project. The aim of the pit field investigation was to establish the nature, character, depth and extent of the potential archaeological pit features at five pitfields. Existing LiDAR data was complemented by an electrical resistivity imaging (ERI) survey and soil analysis of auger samples retrieved from 10 pits was also carried out.

The ERI investigation determined that the pits vary in depth below ground level (bgl) between 0.7-2.2m bgl. The soil analysis demonstrated that some of the pits are more likely than others to contain cultural remains. The LiDAR and ERI data agree on the dimensions of Pits 6, 9 and 10, however there are significant differences for Pits 1, 2, 4, 5, 7 and 8 (larger in the LiDAR data) and Pit 3 (which has a much larger sub-surface anomalies than the LiDAR data suggests).

The soil analysis showed a wide range in moisture content (19-61%), mass specific magnetic susceptibility (2.6-43 x 10-8 m3 kg-1) and organic carbon (3-26%). The magnetic susceptibility data are all reasonably low for an archaeological site, however it does suggest that Pits 7, 8, 9 and 10 are most likely to contain archaeosediments; Pit 10 in particular has responses that are 3-4 times higher than those found in Pits 1, 2, 3, 4 and 6.

The organic content analysis suggests that ‘open pits’ were exposed for a period of time to allow sufficient quantities of organic material to accumulate via either natural or human agency for Pits 2 (at a depth of 0.9-1.25m bgl), 3 (0.3-0.39m bgl), 4 (0.4-0.46m bgl), 5 (0.32-0.39m bgl) and 7 (0.19-0.31m bgl). Pit 7 in particular contained a higher proportion of organic material at 0.19-0.31m bgl than the present near surface deposits (0-0.19m bgl) did, which implies that it was exposed for a long period of time and that accumulated material may not be entirely natural.

The particle size of each auger sample per pit varied considerably. The contents of Pits 1, 8 and 9 were very homogenous and were dominated by very coarse sand (1-2mm). Pits 3, 4, 5 and 6 were homogenous and contained a mixture of particle sizes that were dominated by coarse (0.5mm-1mm) or very coarse sand (1-2mm). Pits 2, 7 and 10 were heterogeneous with a slight dominance of coarse (0.5mm-1mm) or very coarse sand (1-2mm) particles. In some cases, the auger depth of investigation was less than half of the estimated depth of the pits as suggested by the ERI survey, which encountered compacted layers – these will require powered mechanical methods of excavation if further investigation is required.

Earthsound Archaeological Geophysics Prospect House Drumagh Claremorris Co. Mayo Ireland