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2. Pelly Mountain Ice Flow
Figure 1. Location of the Pelly Mountain study
area relative to the glacial limits in Yukon
Yukon Geological Survey
In 2003, mapping of ice-flow patterns in the Pelly Mountains began in order to better understand the depositional history of the glacial deposits in that area (Fig. 1). Kristen Kennedy conducted an undergraduate thesis study of the Seagull Creek drainage in the Pelly Mountains. The goal of the project was to map the surficial geology (Kennedy, 2005 - 
19MB) and determine the glacial history of the upper portions of the drainage. This work aimed to assist on-going mineral exploration in Seagull Creek by Ross River Minerals, who had discovered numerous mineralized glacial erratics in an area of thick overburden coverage on the Tay-LP claims. From this study it was determined that ice flow within the high mountain valley had been up-valley during the late stages of the last glaciation.These results forced industry to re-think their geochemical data and the potential source areas. It also forced us to look for answers as to why the ice was flowing up-valley and determine its geographic scope (Kennedy and Bond, 2004 - 2MB)
In seeking to explain the Seagull Creek glacial geology it was determined that nearly all of the Pelly Mountains had been overridden by the northward-flowing Cassiar ice lobe during the last glaciation (Fig. 2). This meant that all the southward-flowing drainages in the Pelly Mountains experienced up-valley ice flow during glacial maximum and through early deglaciation.
Figure. 2. Schematic depiction of the Cassiar
lobe flowing into the Pelly Mountains
In 2004, field work was conducted along the southern flank of the Pelly Mountains to document the glacial stratigraphy in an attempt to further expand our understanding of the ice-flow history. These results confirmed our theory and provided additional detail about the growth of ice within the Pelly Mountains at the onset of the last glaciation and during its final phase. (Bond and Kennedy, 2005 - 8MB)
More recently in 2005, field work was expanded westward into the Big Salmon Range of the Pelly Mountains. Reconnaissance air-photo interpretation confirmed that this portion of the Pelly Mountains had also been overridden by the Cassiar ice lobe. However, the Big Salmon Range is physiographically oriented transverse to the main body of the Pelly Mountains which meant the affects of an overriding ice sheet may behave differently from what we had documented in 2003 and 2004. The Big Salmon Range also has placer gold potential which needed addressing in light of this glacial history. Results from this field work have identified large areas of meltwater ponding on the east side of the range which drained westward over mountain cols subjecting these to significant meltwater erosion. This work is currently in progress. Anticipated products include a compilation map of ice flow indicators and trajectories for the Big Salmon Range.