2 Study Area
Peninsula Point is located within the Pingo National Park, 6 km
southwest of Tuktoyaktuk, Northwest Territories, Canada (Figure 2). The
regional landscape lies within the zone of continuous permafrost, is
dominated by rolling hills with a maximum elevation of about 50 m, and
thermokarst lake coverage of between 30 and 50 % (Mackay, 1963).
Surficial soils consist of various glaciolacustrine and glaciofluvial
deposits, a result of its position at the northern edge of the
Laurentide ice sheet at the end of the last glacial period (Murton et
al., 2005; Mackay, 1971). The climate in the region is considered
subarctic, with temperatures below freezing from October to late May,
reaching a low of approximately -25 °C between December and March.
Temperatures are typically above 0°C from late May to September,
coinciding with the period when snow and sea ice cover are largely
absent (Burn & Kokelj, 2009). Permafrost in the region is continuous,
with temperatures between -6 and -7 °C (Burn & Kokelj, 2009). The
Peninsula Point island itself is characterised by a 2 m to 10 m thick
layer of clay rich diamicton, atop a MI body of between 5 m and 20 m
thickness, some of which lies below sea level. Below the ice lies a
layer of deltaic sands (Mackay, 1963). The MI layer is understood to
have formed as ground water, sourced from nearby receding glaciers, was
forced toward an aggrading permafrost table less than 14,000 years BP
(Mackay & Dallimore, 1992; Moorman et al.,1998). Shoreline retreat, MI
exposures and RTSs dynamics at Peninsula Point have been monitored since
1935 (Mackay 1986), allowing it to become a “type locality” for
massive intra-sedimental ice in the western Canadian Arctic (Murton et
al., 2005). These features make it an ideal site for assessing the role
of MI and headwall properties on RTS activity.