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Overlying on till covering the bedrock, the esker is composed of glaciofluvial sediments, including sands, gravels, pebbles and a greater or lesser amount of blocks and some fine sediment such as silts and clays. The unconfined aquifer designates the top part of the esker, which is located above 344 m whereas no deposit covers the esker; the unconfined aquifer is vulnerable to contamination from the surface. The esker is recharged with precipitation percolating in the upper part of the esker. Once in the system, water flow includes two components; longitudinal and transversal. The latter is associated with the confined aquifer. The longitudinal component is the one that seems to mostly control groundwater flow and designates groundwater flow in the unconfined aquifer. Water flows south from the rocky topographic high to north at least up to Eska. Further north between Amos and Eska pumping, it is difficult to determine flow directions as the piezometric surface is relatively flat. In the northern part of the esker, water flows southward towards Amos catchment area. It is also possible to identify three water divide lines, one of which corresponds to the point rise in the bedrock. This boundary, located between Amos and Eska pumping is mobile. Its locations is influenced by the pumping and isn't waterproof. There are two sub-basins; Eska and Amos which are interconnected. The other two water divide lines are located in the southern extension of the esker and the northern part of the esker. The north line also seems to be mobile and can move in function of the pumping rate of Amos. Groundwater is exploited for municipal purposes by the city of Amos and for bottling by Eska. It is characterized by an impressive quality. In the center of the esker, the water is modern (younger than 1950), while it is considered fossils (more than 6000 years BP) at the base of the esker. |
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Physiography
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| Hydrogeological region | Canadian Shield |
| Hydrogeological context | |
| Relief | The terrain in vicinity of St .Mathieu/Berry esker is a clay plain which elevation is around 265-300 m. The esker designates a topographic high with elevations above 344 m in the unconfined aquifer, located on the top of the esker. The highest elevations are approximately 500 m. For the confined aquifer, the elevations are lower than 344 m. |
| Area | 51.00 km2 |
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Lithology
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| Description | The bedrock is characterized by metavolcanic, mafic and intermediate rocks (andesite, basalt, amphibolite and others). The unit at the base of the stratigraphic column is till. Its thickness may vary, but it is generally 1 to 2 m. It is very compact and often associated with rock. The till is covered by glaciofluvial deposits, forming among other St-Mathieu/Berry esker. The esker is composed of sand, gravel, pebbles and generally contains a greater or lesser amount of blocks and some fine sediment such as silts and clays. The unconfined aquifer refers to the part of the esker that is located above 344 m. |
| Source | |
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Aquifer
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| Aquifers | List of aquifer
unconfined aquifer of the esker |
Groundwater Information Network