Monday, October 29, 2018
The Earth’s Biosphere
The biosphere is defined as the sphere or area around the planet Earth where life exists. This zone of life is vast. Most lifeforms live on or near the surface of Earth. However, some live deep within the hydrosphere (oceans, lakes and streams), while others thrive in the depths of the lithosphere (solid portion of Earth). For this reason, mapping the exact borders of the biosphere is quite challenging.
Life Affects the Landscape
The lifeforms that make up the biosphere do more than just live on Earth. They also interact with it and are responsible for making great changes in the way that the Earth has evolved.
Consider the atmosphere. Our atmosphere is comprised of approximately 21% oxygen. Where did that oxygen come from? The early Earth did not have very much oxygen in the air. Most of it had been trapped by the seas, and locked up in the rocks and soil. Slowly over millions of years, plants released oxygen into the air, greatly increasing its abundance, and making animal life possible.
Life affects the landscape in many other ways. Plant roots help keep soil from being carried away by rain water. Small rodents and reptiles dig tunnels, beavers build dams, creating temporary lakes and ponds, and humans build a variety of projects large and small.
Without life, the planet Earth would have evolved very differently indeed.
Cycles, Balance, and Life
For hundreds of millions of years, the chemicals and elements found on Earth have remained relatively constant, or in other words, they have changed very little. The amount of one element or chemical in the Earth’s surface is practically the same as it was many millions of years ago. This consistency is one of the things that makes life on Earth possible.
This balance is maintained via complex interactions or cycles between the Earth and its organisms, or lifeforms. The elements of the Earth are taken into lifeforms, used to sustain the organism, and later released in the form of waste, or through decomposition upon the death of the organism.
Most of these cycles only take a few months or a few years to complete. However, some can take many millions of years.
https://kidsgeo.com/geography-for-kids/the-earths-biosphere/
Look at the picture and identify the Biosphere:
Wednesday, October 3, 2018
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