Okoro Daniel O.
Description of Geologic Materials
Geologic materials are classified with respect to their porosity and permeability. These two factors controls the occurrences of groundwater in geologic materials. They affect the important and description of geologic material with respect to Hydrogeology.
Geologic Materials can be classified into four (4), they are;
- Aquifers
- Aquiclude
- Aquitard
- Aquifuge
AQUIFERS: They are geologic materials that are porous and permeable and can yield economic quantity of water to wells and springs.
Examples of aquifers: Limestone, fractured shales, politic limestone, fractured granite, etc.
Examples of Aquitard: Unfractured shales, solid granite, clay.
Examples of Aquiclude: Shales, clays, mudstone, and siltstone.
Examples of Aquifuge: Solid igneous rocks.
AQUIFERS: They are geologic materials that are porous and permeable and can yield economic quantity of water to wells and springs.
Examples of aquifers: Limestone, fractured shales, politic limestone, fractured granite, etc.
TYPES OF AQUIFERS
We have several types of aquifers, some of which are;
- Unconfined Aquifers
- Confined Aquifers
- Artesian Aquifers
- Perched Aquifers
- Idealized Aquifers
- Fractured Aquifers
UNCONFINED AQUIFERS: Are aquifers that NOT BOUNDED above or below by a confining stratum. They are also called WATER TABLE AQUIFERS. This is because, the water table undulates with respect to RECHARGE and DISCHARGE in such aquifers.
Unconfined aquifer, the confining stratum which is normal an impermeable rock strata does not exist at the top but may exist below. Also, they are recharged from the surface by process of precipitation [Precipitation: (meaning) is any liquid or frozen water that forms in the atmosphere and falls back to the Earth. It comes in many forms, like rain, sleet, and snow. Along with evaporation and condensation, precipitation is one of the three major parts of the global water cycle.].
Unconfined Aquifers in most cases are partially filled (are not completely filled) with water and the position of the water table varies with the topography, areas of recharge and discharge, and the permeability of rocks. The amount of water in unconfined aquifers is also controlled by change in seasons.
CONFINED AQUIFERS: Are aquifers that are bounded above and by impermeable geologic stratum.
ARTESIAN AQUIFERS: Are specialized form of confined aquifers. They are aquifers in which the confinement pressure is strong enough to make the water to spring in their own accord. Artesian Aquifers gives rise to springs and wells. Artesian Aquifers is like WATER FOUNTAIN.
PERCHED AQUIFERS: Are aquifers that occur in the midst of the unsaturated zone. This kind of aquifers occur when water is trapped by a porous body in the midst of an unporous body.
FRACTURED AQUIFERS: Are aquifers that occur in fractured rocks. They are sometimes called “FRACTURED ZONE AQUIFERS“. This is because the fractures can house water which is sustainable in economic quantity. Fractured Aquifers occur in areas where tectonics activities has occurred in the past. Therefore, it does not matter if these rocks are porous or permeable but the occurrence and distribution of groundwater is dependent on the connectivity and distribution of the featured system.
IDEALIZED AQUIFERS: Are aquifer which are isotropic and homogeneous. Such aquifers do not occur in real life but are used in mathematical simulation to develop geological theories.
