Understanding Geological Water Formations: Aquifer, Aquiclude, Aquitard, and Aquifuge

Geological formations underground hold water in different ways. How much water they can hold and how easily water can flow through them determines what they are called. Let's look at the different types of these formations:

• Aquifer: This is a permeable geological formation. It contains water and is capable of transmitting significant quantities of water. Wells are typically drilled into aquifers to extract groundwater. Examples include sand, gravel, or fractured rock.
• Aquiclude: This is an impermeable or practically impermeable geological formation. It may contain a large amount of water in its pores, but it cannot transmit or supply water at a significant rate. Clay is a common example of an aquiclude.
• Aquitard: This is a semi-permeable geological formation. It contains water and can transmit it, but at a very slow rate compared to an aquifer. It can act as a leakage layer to or from adjacent aquifers. Silty clay is an example.
• Aquifuge: This is an impermeable geological formation that neither contains nor transmits water. Solid granite or basalt rock can act as an aquifuge if not fractured.

The question describes a formation that is "impermeable", "contains water", but is "not capable of transmitting and not supplying significant quantity". Let's match this description to our definitions:

Based on the table and definitions, the term that fits the description "Impermeable formations which contains water but are not capable of transmitting and not supplying significant quantity" is Aquiclude.

Therefore, an aquiclude holds water but acts as a barrier to groundwater flow, preventing extraction in useful amounts.