Prehistoric Rocks Tell Plate-tectonic ProcessRocks discovered by Chinese geologists reveal that plate-tectonic process, which scientists worldwide have come to understand for only three decades, began at least 2.5 billion years ago.GSA Today, a US-based geology magazine, published a cover story Wednesday on the findings of Li Jianghai, a geologist with the Beijing University. Li and his colleagues discovered some mantle rocks, all with original textures and minerals, at the foot of the Great Wall in north China's Hebei Province in May 2001. Experts at Rutgers University and St. Louis University confirmed in April this year that the rocks were formed during seafloor expansions in the Archean Age, earth's earliest geologic period, some 2.5 billion years ago. Prior to the discovery, most scientists believed plate-tectonic process started two billion years ago. GSA Today described Li's discovery as "important" and "fantastic", and called on international academic circles to carry out further research on the north China craton. Similar mantle rocks found in LiaoningThe plate-tectonic theory, which was formed in 1968, says the earth consists of six major plates -- Euroasia, the Pacific area, Africa, the Indian Ocean, American and Antarctica -- and some minor plates, all of which move horizontally.The theory also holds that ocean basins are formed where these plates expanded, and mountains appeared when they collided. The new discovery may help scientists explore further the formation and evolution of primitive marine lives and the origins of life on earth, Li said. The scientist said he would try to discover traces of pre-historic lives in his future research. Li also revealed his recent discovery of similar mantle rocks in Liaoning Province, northeast China, and believes relics of prehistoric plate collisions would be found some 700 kilometers north of Beijing. Interestingly, Liaoning Province is also home to some fossils of the world's oldest flowers and feathered dinosaurs that are taken as evidence for the possible evolution of the mammoth creatures into birds. |
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