Base de données de recherche des TNO

Régions: Dehcho Region

étiquettes: physical sciences, lichen, glaciology, botany, rock outcrops, glacial history, glaciers

Description du projet: The objectives of this study are to: 1) inventory the size and morphometry of glaciers in the Ragged Range; 2) find and document geological and botanical evidence of former glacier activity; 3) develop a chronology for Holocene glacier activity in the Ragged Range; and, 4) develop one or more growth curves for lichens growing on carbonate and/or silicate rocks. Also, the field reconnaissance and basic data produced in this work will help to inform debate about the possible expansion of Nahanni National Park. Field work is an essential part of this project, but due to logistical challenges the researchers will restrict field operations to a small team and limit investigations to those sites that have well preserved and datable evidence of glacial activity. The field team will fly by helicopter to either North Moraine Hill Glacier or Brintnell Creek for 3 days. They will then be moved by helicopter to another site that they will select during their first overflight. Digital calipers will be used to measure several dozen of the largest lichens growing on moraines down valley from glaciers in the Ragged Range. A few samples (10-20) will be taken of the most common lichens at these sites to allow laboratory identification to species level. An increment borer (5mm diameter) will be used to retrieve increment cores from the base of several dozen of the oldest looking living conifers and shrubs growing on moraines and at the timberline at the study sites. The cores will be used to establish ring-width chronologies and to estimate the approximate age of lichen covered surfaces. If glacier damaged snags are discovered, some of these (less than 20) may be cross-cut at the base so as to help establish the timing of glacier advance/retreat and/or extend the chronology beyond what is present in the living trees. Grab samples of organic debris that is buried in glacier moraines may also be taken for radiocarbon analysis. This evidence is needed to provide dating controls for glacier advance and lichen growth rate calibration. A report and glacier inventory will be submitted to Nahanni National Park. The study will be conducted at North Moraine Hill Glacier, the headwaters of the Brintnell Creek and/or other glacier forefields in the Ragged Range, from July 19 to July 25, 2005.