Global View
Breaking News on Geologic Time: In 2004, for the first time in 120 years, geologists made a major modification to the geologic time scale. The Ediacaran time period (approximately 620 to 542 million years before the present) was adopted by an International Commission of Scientists as the first official time period of the Proterozoic Era. The Ediacaran is defined as a period of explosive growth of soft bodied animals, sponge-like and jellyfish-like creatures. The Ediacaran represents the time when complex life first developed. The time period ends when hard bodied (bony) animals evolved in the Cambrian. The best known Ediacaran creatures appear to be immobile blobs, disks, fronds, and mattress-like shapes that went extinct and failed to develop ancestors.
The founding of geologic time was based on the observational science of early geologists in the 1800s. A century later, the emerging field of radioactivity verified that the Earth was billions of years old. Although geologic time is a tenant of all sciences, biologists and geologists struggle alike in having the science of evolution and geologic time taught in the primary and secondary school systems.
Geologic time leads to some of the ideas of plate tectonics; essentially, that, given massive amounts of time, big things can happen. Originally proposed as Continental Drift in the early 1900s, plate tectonics did not become a theory until modern scientific equipment answered the remaining questions geologists had on how continents could possibly move.
The discoveries of geologic time and plate tectonics were lead by average people making interesting observations about their surroundings. These initial discoveries have been supplemented by decades of scientific experiments that have continued to prove the ideas correct, discover new evidence, and pose new questions.
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