This area extends for 5km between Lough-a-Tirrive [H532 786] and Fallagh Upper [H557 833] and forms a valley between the upland areas of Mullaghcarn and Mulderg [H540 789] drained by Glensawisk Burn. Glacial sediments infill a pre-existing bedrock valley and are characterised by flat spreads of deltaic and glaciofluvial sand and gravel which have been heavily dissected by glacial meltwater to a depth of 40-60m. Up-valley, these sediments onlap onto bedrock; down-valley they onlap onto localised soliflucted diamict. Peat has developed on all substrate types to a depth of 1-2m. Near Stradowan Bridge [H535 799] there is a series of three linked former sand and gravel pits, measuring 300m long by 150m wide. The pits are dug at 210-220m into the eroded upper delta/outwash surface, which reaches 235m O.D. All other pits offer exposure of similar sequences.
The northernmost exposure is of clast and matrix-supported gravel beds interbedded with massive and vaguely stratified well-sorted sand beds. These facies occur in stacked planar or cross-bedded sequences separated by laterally-continuous planar erosional contacts. This exposure records the deposition of a variety of well-sorted sediments in a subaqueous depocentre by massflow and grainflow processes. Variations in flow pulse energy can account for the observed facies variability and continuity. High-energy pulses are associated with massive, matrix-deficient gravel pods and lenses, often with erosional basal contacts. Planar basal contacts demonstrate a dominant longitudinal component of the flow regime in which basal scouring occurs. The stacking and overlapping of the different sediment sequences seen here is characteristic of a shallow-water aggrading delta or outwash environment with variable rates and locations of sediment input. The Glensawisk Burn delta resulted from a southward ice retreat through Lough-a-Tirrive towards Mountfield based on the evidence of moraine ridges composed of local angular material near Lough-a-Tirrive. Evidence of ice-marginal activity, recorded in other sections in the Stradowan area, includes bed contortion and shortening, shearing of clay layers, water escape structures and some large-scale open folding.
