Evidence shows that life probably began in the ocean at least 3.5 billion years ago.
Photosynthesis began more than 2.5 billion years ago—the Great Oxidation Event. But it took hundreds of millions of years for enough oxygen to build up in the atmosphere and ocean to support complex life.
The first organisms were single-celled microbes. For nearly 2.3 billion years, life consisted of these alone. Then, about 1.2 billion years ago, more complex multi-celled organisms evolved.
Since then, life forms have grown much more diverse—though not continuously. The record reveals bursts of evolution and expansion interrupted by massive extinctions. Big changes happen through small steps over geologic time. We can trace the path of evolution in Earth’s rocks and fossils.
This image gallery shows renderings of what sea life looked like during various periods of deep time.
FAQs
Plate tectonics, for example, has caused the formation and movement of oceanic plates, which has led to changes in ocean currents, sea level, and climate over millions of years. Volcanic activity has also played a role in the evolution of the oceans.
When did oceans first appear on the geological time scale? ›
4400 mya – The Earth's first oceans formed.
It then cooled, fell back down as rain, and formed the Earth's first oceans. Some water may also have been brought to Earth by comets and asteroids.
What is the study of the history of the oceans in the geologic past? ›
Paleoceanography is the study of the history of the oceans in the geologic past with regard to circulation, chemistry, biology, geology and patterns of sedimentation and biological productivity.
What is the geological process of the ocean? ›
Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth's lithosphere—split apart from each other. Seafloor spreading and other tectonic activity processes are the result of mantle convection. Mantle convection is the slow, churning motion of Earth's mantle.
What are the 4 geological features? ›
These processes include plate tectonics, weathering, erosion, deposition, and weather. Plate tectonics is the movement of lithospheric plates driven by the internal heat of Earth and the force of gravity. Weathering, erosion, and deposition result from the water cycle, wind, and gravity.
What is the geologic process? ›
Geologic Processes
These include: diagenesis, Earthquakes, erosion, glaciation, hydrothermal processes, isostacy, land subsidence, liquefaction, metamorphism, sediment transport, sedimentation, tectonic processes, volcanic activity, Earth tides, deformation, soil formation, magnetic storms, and mass wasting.
Did all life come from the ocean? ›
Evidence shows that life probably began in the ocean at least 3.5 billion years ago. Photosynthesis began more than 2.5 billion years ago—the Great Oxidation Event. But it took hundreds of millions of years for enough oxygen to build up in the atmosphere and ocean to support complex life.
Was there a time when Earth had no ocean? ›
Earth has been around for about 4.5 billion years, but there was no ocean in sight for the first billion or so. That's in part because the planet was too hot for water to accumulate in liquid form.
How did the ocean get so deep? ›
The extreme depth of the Mariana Trench and other oceanic trenches is caused by subduction. This is where on the boundary of two converging tectonic plates, one descends down into Earth's mantle, creating a deep trough.
What is the deepest part of the ocean? ›
The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred kilometers southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 10,935 meters (35,876 feet) deep.
Most of the ocean consists of total darkness.
Light does not penetrate beyond a surface layer of about 600 feet, which is where all photosynthesis in the ocean takes place. Almost all life at deeper levels is supported by “marine snow” falling down from the ecosystem at the ocean surface.
Is 80% of life on Earth in the ocean? ›
The ocean covers 71 percent of the Earth's surface, and 50-80 percent of all life is found under its surface. Millions of people rely on the ocean for their livelihood.
How have the oceans changed? ›
When averaged over all of the world's oceans, sea level has risen at a rate of roughly six-tenths of an inch per decade since 1880. The rate of increase has accelerated in recent years to more than an inch per decade. Changes in sea level relative to the land vary by region.
How have sea levels changed over Earth's history? ›
Over geologic time sea level has fluctuated by more than 300 metres, possibly more than 400 metres. The main reasons for sea level fluctuations in the last 15 million years are the Antarctic ice sheet and Antarctic post-glacial rebound during warm periods.
What is the geological development of the Earth's oceans? ›
Development of the oceans
Volcanic degassing of volatiles, including water vapour, occurred during the early stages of crustal formation and gave rise to the atmosphere. When the surface of Earth had cooled to below 100 °C (212 °F), the hot water vapour in the atmosphere would have condensed to form the early oceans.
How did Earth's oceans evolved? ›
The ocean formed billions of years ago.
Water remained a gas until the Earth cooled below 212 degrees Fahrenheit . At this time, about 3.8 billion years ago, the water condensed into rain which filled the basins that we now know as our world ocean.
