Aquatic ScienceFossil Aquifers and Marshes

It is ground water that has remained sealed in an aquifer for a long period of time.

The water contained in the aquifers cannot be replenished and may have been locked in for thousands of years.

Water in these aquifers can be referred to as fossil water or Paleowater.

The age of the water is what gives it the name “fossil water”.

What is a Fossil Aquifer

Fossil water aquifers can be brackish or salt water.

They can be contaminated. Fossil aquifers can also be highly

radioactive depending on the surrounding geology

Problems with Water Quality

Fossil aquifers are non-renewable resources. Changes in the surrounding geology have

sealed the aquifer from precipitation “trapping” the water.

Water in these aquifers is stagnant, and has little if any flow.

Non-Renewable Resource

Most often found in arid climates, fossil and other non-renewable aquifers are an important water resource for many nations.

Fossil water resources will eventually run out once they begin being used.

Fossil Water Resources

For over 50 years Libya has relied on fossil water supplies that are now dwindling.

India, China, and Mexico all depend on non-renewable water taken from ancient aquifers.

Some Countries Rely on Fossil Aquifers

In the United States a number of the Great Plains states take a considerable amount of their water from a fossil water aquifer.

This water reservoir is the Ogallala Aquifer or the high planes Aquifer.

Estimates forecast this aquifer being empty in 25 years.

The disruption is likely to be immense as the aquifer covers portions of eight states, and supplies 82% of the drinking water for these states and around 30% of the water used for crop irrigation in the area.

The United States

Marshes are defined as wetlands frequently or continually inundated with water.

Marshes recharge groundwater supplies and moderate streamflow by providing water to streams.

Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, and moss.

What Are Marshes?

Brackish marshes are transitional between freshwater and salt marsh communities.

Brackish marshes are found on the edges of sounds and estuaries. 

Sound: A long body of water between an island and the mainland.

Brackish Water Marshes

Northern Water Snake

The brackish zone is where the fresh rivers meet the salty ocean.

Water from rivers dilute the saltwater. Water in brackish marshes rises and falls

with the tides.

Brackish Zone

Plants that live in a brackish marsh depend on how salty the water is.

Saltier brackish marshes have Black Needlerush (Juncus roemerianus) and Saltmeadow Hay (Spartina patens). 

Brackish marshes that are less salty may have large stands of Giant Cordgrass (Spartina cynosuroides) and Sawgrass (Cladium jamaicense). 

Brackish Marsh Plants

Black Needlerush

Cordgrass

Left: View of a brackish marsh in the Mississippi River Delta, with a simplified diagram showing how biological processes influence marsh elevation relative to sea level. Plant production contributes organic matter, causing upward expansion of the soil surface. As marsh elevation changes, flooding and salinity regimes also change and have a feedback effect on plant production. Increases in CO2 concentration contribute to global warming and sea-level rise but also stimulate plant production, leading to faster gains in elevation.