The hydrosphere and geosphere are two of the Earth’s four spheres; but how does the hydrosphere interact with the geosphere?
When air in the atmosphere contains too much water, precipitation—such as snow, rain, or sleet—can fall to Earth’s surface, thereby connecting the hydrosphere with the geosphere.
Precipitation causes erosion and weathering (a process in which large rocks are broken down into smaller ones) on the upper layer of the geosphere known as the lithosphere.
Erosion slowly breaks down large rocks into smaller ones, promoting new sedimentation.
Hydrological Cycle and the Geosphere
The movement of water among the Earth’s four systems is, in essence, a cycle.
However, not all water on Earth is in a constant state of transformation through the “hydrological cycle.”
For example, water in a glacier may remain frozen for thousands of years before melting and infiltrating into an aquifer or evaporating into the atmosphere (or even moving more slowly through the geosphere).
Rain that soaks into parched soil may be absorbed by thirsty plants, which then transpire the water back into the atmosphere.
But it will only be in the atmosphere for a short time since it is being cycled from the biosphere to the geosphere to the hydrosphere, and then back to the biosphere.
Note: A complete hydrological cycle on Earth involves the hydrosphere, geosphere, atmosphere, and biosphere.
Hydrosphere as a Medium for Chemical Reactions in the Geosphere
The geosphere is the soil, rocks, and minerals of Earth’s crust and interior.
The hydrosphere includes liquid underground water, frozen surface waters, and water vapor in the atmosphere.
The hydrosphere (an element of the Earth’s water cycle) is affected by the geosphere in many ways.
Water can be found on the surface of Earth, below ground level, and in Earth’s mantle.
This interaction between different elements is essential for both the geosphere and the hydrosphere.
Note: Chemical compounds in minerals can react with water to break down rock,
This results in a change in water properties (e.g., dissolved salts), while at the same time increasing its ability to dissolve additional minerals.
IceCaps and Vapor in Geosphere’s Lava
Much of Earth’s water is stored in the oceans.
The rest of the planet’s water is ice-locked in polar ice caps and glaciers and stored deep within the Earth’s crust in the geosphere.
However, some of this water periodically escapes into the atmosphere when lava cools above or near bodies of water.
This occurs most frequently when lava cools while submerged in seawater, but it can also happen on land if lava flows into or near a body of water.
Fact: Earth is home to about 326 million cubic miles of water. About two-thirds of this massive amount are contained in the oceans and seas.
Earth’s Convection Currents and the Geosphere
Although the oceans are entirely comprised of water, there are small amounts of dissolved solids contained in the seawater that impart a slight salinity and help make it denser than fresh water.
Because of this temperature-dependent density difference, water naturally flows from areas of higher concentration to regions of lower concentration and regions with higher temperatures to regions with lower temperatures.
Additionally, heat-related convection currents within the Earth’s mantle can also drive the process of planetary-scale ocean circulation.
Therefore, the geosphere is a source of energy that makes the global convectional cycles complete.
Hydrothermal Vents
The hydrosphere and the geosphere also influence each other in several significant ways, including their interaction at hydrothermal vents.
Hydrothermal vents are found along the Mid-Atlantic Ridge.
This rift valley separates the North American plate from the Eurasian plate (the North American plate is sliding below the Eurasian plate).
The hydrothermal vents at the Mid-Atlantic Ridge are present because seawater circulates through hot volcanic rocks, often located at the new oceanic crust being formed.
The vents are also found beneath the ocean floor aboard volcanoes.
The hot water emerges into cold water, causing minerals to precipitate out of the solution.
These minerals are rich in iron, copper, zinc, and other metals that were dissolved in hot water.
The outflow accounts for twenty percent of the heat loss on Earth.
Erosion
Water is crucial for weathering and erosion of rocks in the Earth’s geosphere.
Rocks, in turn, are responsible for creating the surface features that enable ice melts and water bodies to flow back into the oceans.
Water from the oceans evaporates and forms clouds, eventually dripping back down as rain.
These processes cause erosion, developing the land into mountains, valleys, and plains.
The geosphere's hard rock layer created by this erosion allows meltwater to form rivers that flow into oceans.
Aquifers in the Geosphere
Water is present in all the major Earth systems, notably in their respective hydrospheres.
The hydrosphere can contain water that evaporates into the atmosphere.
Water vapour in the air may be precipitated as rain, to later run across the surface of the Earth to lakes and oceans, eventually draining into rivers and streams, and then finding its way back to the ground again.
Even though a little bit of water could go with a little bit of soil when it erodes or washes away from areas near the sea or lake, or percolate through the rock into the groundwater that joins up with other bodies of water or moves into deep aquifers.
Lakes, Oceans, and the Geosphere
A body of groundwater can get confluent with another body and become part of a larger body of water (a lake, an ocean) at some later point.
Plants take up water through their roots and give it up again through their leaves in a process called transpiration.
Animals can drink from lakes, rivers, or ponds and breathe out water vapour to be re-dissolved into clouds.
This water again can fall as rain on land somewhere else to form rivers, lakes, or ponds – all over again.
The Energy Sources for the Hydrological Cycles
While it’s essential to know how does the hydrosphere interact with the geosphere, it’s equally noteworthy to understand the sources of energy to make such interaction possible.
The hydrological cycle is driven by both internal and external sources of energy.
Internal sources of energy include gravity which emanates from deep in the geosphere, pulls rain down to Earth.
This enables it to soak into subsurface soil or rock or runoff over land, and the Earth’s internal heat, which makes the inside “hotter” than the outside, causing evaporation.
External sources of energy, such as the sun, provide solar energy that warms the surface of the Earth and causes evaporation.
Note: These two forces acting simultaneously on water cause it to be cyclical.
Water Transitions Through the Spheres
The movement of water on Earth is quite complex. It’s important to note that there is never “new water” created in either the geosphere or hydrosphere. Water transitions from one sphere to another.
It can also appear in the vaporous form when it evaporates from the surface of the Earth or bodies of water, at which point it may condense and return to Earth as precipitation.
For example, in human bodies (a component of the biosphere), this dense substance makes up 70 percent of our bodies and is always on the move.
It infiltrates into the soil to recharge groundwater or runs off to join streams, rivers, and eventually the world ocean.
The movement of water on Earth encompasses every primary system of earth science:
- geology,
- meteorology,
- hydrology,
- bioscience, and
- astronomy.
Final Thought
Water cycles best explain how does the hydrosphere interact with the geosphere, which goes way beyond erosion.
The Earth’s geosphere is the solid layer that stretches from the crust to the core. It includes tectonic plates and sedimentary rock
The hydrosphere, or the water on or near the Earth, has oceans, rivers, lakes, glaciers, and snow cover on land.
Most of the water on Earth is in liquid form: it is in oceans and seas.
Earth’s solid rocky crust that covers a molten inner core within a thin form is the basis of geosphere-hydrosphere interaction through geysers, springs, and other volcanic activities happening beneath the Earth’s surface.
