Overview:
The oldest fossils found on Earth are not dinosaur bones or the insect creatures known as trilobites. They are one-celled organisms that left ancient deposits over 3.5 billion years ago. Some forms of those one-celled organisms still exist today, and are forming similar structures throughout many places in the world.
What Are Stromatolites?
Stromatolites are distinctive rock formations in which layers of sediment are formed in narrow bands. Microbes trapped different particles in layers as they decayed, resulting in unusual wavy patterns as the rock was formed. Organic material buried deep within the darker strands of rock provides evidence that the patterns were formed by microscopic living organisms, although some may have occurred during other geological processes.
Where Are They Found?
Stromatolites are found in many different parts of the world, wherever the oldest rocks have been found. Some have been found in rock formations in Banff National Park, Glacier National Park, in Estonia, Greenland, Namibia in Africa, and in many parts of Australia. They occur in several different shapes and sizes. Many of the stromatolite formations may have been worn away by erosion, as well as other geologic processes.
Why Are They Important?
The one-celled organisms that resulted in stromatolites used water, carbon dioxide, and sunlight to sustain themselves through photosynthesis. In the process, they released large amounts of free oxygen into the atmosphere. Some of that free oxygen combined with iron and other metals , causing oxides to form, while other amounts stayed in the atmosphere. The oxygen-rich atmosphere could sustain more complex forms of life.
How Are They Formed?
When stromatolites were first discovered, they were thought to be formed from only one type of one-celled organism, blue-green algae. However, there were probably other types of one-celled organisms that used photosynthesis to sustain themselves. The microorganisms that were living at the time protected themselves from ultraviolet light by a sticky substance that trapped sediment in its layers. As one layer became opaque from the trapped sediment, another layer of organisms grew in order to take advantage of the sun’s energy. That layer of organisms protected itself by a sticky substance, so the cycle was repeated.
Interested in Science tutoring services? Learn more about how we are assisting thousands of students each academic year.
SchoolTutoring Academy is the premier educational services company for K-12 and college students. We offer tutoring programs for students in K-12, AP classes, and college. To learn more about how we help parents and students in Fredericton, NB, Canada visit: Tutoring in Fredericton, NB, Canada