| Popis: |
The Firth River is located in a sector of northern Yukon that has not been touch by the latest glaciations. The objective of the study is to determine if the Firth River naled ice has an impact on the surrounding soils and vegetation. The analysis of the soils and the observation of the vegetation along 3 transects, one longitudinal and 2 cross-sectional, has showned a differential evolution. The study and datation of an island in the center of the valley has permitted to establish that the river has cut in the valley after 16084 +/$-$ 340 B.P. The grain size distribution of the soils gives an estimation of the deposition modes which, in this case, is mainly fluvial but where the ice may play a role in its dynamic. The soils salt concentration show a relationship with the distance from the center of the valley. It is an indicator of the impact of the ice on the soils and act as a signature of the presence of the ice. The observation of the vegetation growing in the valley also show the influence of the ice: its destruction shows the presence of the ice although its development stages indicate the absence of the ice on a long or short term. |
