| Richibucto, Balfron, Pictou, Cumberland Formations fractured bedrock aquifer |
| In ascending order, the geological groups are: basement complex and Horton, Windsor, Riversdale-Mabou, Cumberland, and Pictou Groups (Richibucto, Balfron, and Pictou und). The internal stratigraphy of these units is complex and often laterally discontinuous, as a result of different sedimentation rates, synsedimentary faulting, and reworking. Horton, Windsor and Mabou groups form a hydrogeological unit characterized by a poor aquifer potential. The undivided Cumberland and Pictou (sandstone, mudstone and siltstone), Richibucto (sandstone), and Balfron (sandstone and mudstone) formations form a hydrogeological unit that assembles the main aquifer units of the area. Cumberland formation is separated of the others by low permeability Salisbury formation. The hydrogeological unit has moderate hydraulic conductivity values suggesting a significant presence of fractures. Groundwater flows in the rock through fractures and interconnected pores between grains. Since the fractures have a much higher permeability than the surrounding matrix, the water flows essentially in the fractures. The hydrogeological unit is covered with a till layer, extending throughout the area. Some alluvial deposits and rock outcrops can be observed. Marine deposits are found along the Northumberland Strait. Considering the general characteristics of the till, the hydrogeological unit underlying is under semi- confined conditions. It therefore presents a moderate vulnerability to contamination. It is the third most important recharge area of the region. Confined and unconfined conditions can also be present locally depending on the composition and thickness of the till. The water is of good quality, but there are some issues as chlorine, iron, fluoride, manganese, sodium, barium, and alkaline ph. |
| Basement Complex aquitard |
| The basement complex belongs to the hydrogeological Appalachian region. This hydrogeological unit is a basement uplift area along large regional St-Joseph - Dorchester fault. It is characterized by rugged terrain. The basement complex receives the largest annual rainfall, but it has the lowest recharge rates throughout the region. It is considered a major regional aquitard showing a bad aquifer potential. The main discharge is Fundy Bay. The hydrogeological unit is covered with a till layer, extending throughout the region. The till has a poor aquifer potential. Some colluvium also overlay the basement complex. Considering the general characteristics of the till, the basement complex is under semi-confined conditions, reducing the risk of contamination. The unit has a low vulnerability. The water quality is good. |
| PEI Group fractured bedrock aquifer |
| In ascending order, the geological groups are: basement complex and Horton, Windsor, Mabou, Cumberland, Pictou and Prince Edward Island (PEI) Groups. The internal stratigraphy of these units is complex and often laterally discontinuous. The PEI group is composed of conglomerate, wackle, red sandstone and mudstone. It is covered with a sandy matrix till unit. This till feature involves high hydraulic conductivity, suggesting a good percolation of surface water. Considering that the hydrogeological unit also has a good hydraulic conductivity, the recharge rates are one of the most important in the region. The unit also shows one of the most important aquifer potential of the area. Groundwater flows in the rock through fractures and interconnected pores between grains. Since the fractures have a much higher permeability than the surrounding matrix, the water flows essentially in the fractures. Groundwater mainly follows the surface topography, flowing into the Northumberland Strait. Considering the weak protection provided by the till, the aquifer is vulnerable to contamination from surface. The groundwater quality is good, but there are some aesthetic problems of iron, manganese, nitrate and lead. |
| Horton, Windsor, Mabou Formations aquitard |
| In ascending order, the rock formations include: basement complex and the three rock Groups (Horton, Windsor and Riversdale-Mabou). The Horton Group consists of a sequence of continental sedimentary and volcanic rocks, overlain by the marine limestone and evaporite strata of the Windsor Group. A thick unit of sandstone and conglomerate (siltstone and mudstone) corresponding to the Riversdale-Mabou, overlies the Windsor Group. These three rock groups have medium hydraulic conductivity. Commonly characterized as weak, the aquifer potentials vary from bad to variable. Riversdale group and the upper part of Windsor group are aquitards. Riversdale-Mabou rocks are covered by a till unit, extending over the entire area. The till also has a weak aquifer potential. Considering the till general characteristics, the hydrogeological unit is under semi confined conditions. It has a moderate vulnerability to contaminations. Confined and unconfined conditions can also be present locally, depending on the till composition and thickness. Horton and Windsor groups have poor water quality, showing problems with chlore, fluoride, manganese, sodium, sulfate, nitrate, arsenic, barium, hardness, pH alkalin and total dissolved solids. |
| South-Central Carboniferous Basin regional aquifer system |
| In ascending order, the hydrogeological units are: basement complex, Horton-Windsor-Mabou, Boss Point, Salisbury, Cumberland und.-Richibucto-Balfron-Pictou und. and Prince Edward Island (PEI). Cumberland undivided formation is separated of the Richibucto-Balfron-Pictou undivided unit by Salisbury formation. The internal stratigraphy of these units is complex and often laterally discontinuous. Horton-Windsor-Mabou unit represents several alluvial-lacustrine or alluvial-marine cycles in the early basin fill. It is covered by multiple stacked cycles of meandering fluviatile, inter-channel, and paludal deposits (Boss Point, Salisbury, Cumberland und.-Richibucto-Balfron-Pictou units). The PEI unit represents strata of the Early Permian. The rock units outcropping are covered by a till layer, whose thickness varies between 0-20 m. The till matrix influences the aquifer potential of the underlying hydrogeological units. Boss Point and PEI are located under a till with a sandy matrix. They have the most important aquifer potentials and recharge rates of the area. These units have a greater vulnerability to contamination by the surface. The formation of Salisbury is located under the till with silty matrix. It is characterized by poor aquifer potential and low vulnerability. Horton-Windsor-Mabou unit also have a low aquifer potential. Groundwater flows through the rock fractures and interconnected pores between grains. Fractures have a much higher permeability than the surrounding matrix, thus water flows mainly in fractures. Northumberland Strait and Fundy Bay are the two major areas of resurgence. The groundwater quality is generally excellent. |
| Boss Point Formation fractured bedrock aquifer |
| In ascending order, the geological groups are: basement complex and Horton, Windsor, Mabou Groups, and Boss Point Formation. The internal stratigraphy of these units is complex and often laterally discontinuous. The Boss Point formation is mainly composed of sandstone, siltstone and mudstone. It is covered with a sandy matrix till unit. This till feature involves high hydraulic conductivity, suggesting a good percolation of surface water. Considering that the hydrogeological unit also has a good hydraulic conductivity, the recharge rates of the Boss Point formation are the most important in the region. The unit also shows one of the most important aquifer potential of the area. Groundwater flows in the rock through fractures and interconnected pores between grains. Since the fractures have a much higher permeability than the surrounding matrix, the water flows essentially in the fractures. Groundwater flow mainly follows the surface topography. Considering the weak protection provided by the till, the aquifer is vulnerable to contamination from surface. The groundwater quality is good, but the area near the Petitcodiac River has some local problems of fluoride, iron, manganese and pH. |
| Salisbury Formation fractured bedrock aquifer |
| In ascending order, the geological groups are: basement complex and Horton, Windsor, Mabou and Cumberland Groups. The latter includes Boss Point, Cumberland undivided and Salisbury formations. The internal stratigraphy of these units is complex and often laterally discontinuous. Salisbury formation is composed of mudstone, siltstone and fine-grained sandstone. It is covered by a till unit which extends over the entire area. It is covered by a silty matrix till unit. This till feature involves low hydraulic conductivity, suggesting a poor percolation of surface water. Salisbury formation has poor recharge rates. The silty matrice of the till allows a better confinement of the aquifer, causing a good protection against contamination from the surface. Despite the moderate hydraulic conductivity of the hydrogeological unit, the aquifer potential is poor (almost considered as aquitard). The groundwater quality is good, but it has some aesthetic problems. Concentrations of chlorine, fluoride, iron, manganese and sodium are high. Locally, there are some problems of nitrate, total hardness and other metal traces. |
| Prince Edward Island regional bedrock aquifer |
| Prince Edward Island is a crescent-shaped cuesta of continental red beds. This sequence is composed of fractured sandstone with minor siltstone red beds. These units show rapid lateral and vertical facies changes and strong cross-bedding features. An unconsolidated sandy till unit overlies almost entirely the bedrock sequence. The till thickness varies from few centimeters to several meters. Commonly, the surficial deposits are not significant aquifers. However, the uppermost portion of the sandstone formation forms a fractured-porous aquifer. This latter is characterized by significant fracture permeability dominated by horizontal bedding plane fractures, in addition to intergranular porosity. The sandstones aquifer is unconfined, except in local areas where less permeable mudstone beds alternate with sandstone to generate semi-confined conditions. The aquifer is vulnerable to surface contamination. It is recharged by precipitation percolating through the till or outcropping bedrock. Water flows in the uppermost part of the aquifer, which is strongly fractured and constitutes a fast path layer for groundwater flow. Groundwater flow follows surface topography and decreases with depth due to lower fracturing causing lower hydraulic conductivity. The aquifer discharges in rivers and seepage at the coastline. It represents one of the few sources of drinkable water. Groundwater is extracted for domestic, industrial/commercial and agricultural uses. Groundwater quality is good, however the nitrate concentration is high due to agricultural activities. This economic sector constitutes a threat to water quality due to its nitrate inputs. |
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