Years Were Longer 1.3bln Years ago: Chinese Scientists

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Last updated at: (Beijing Time) Monday, July 21, 2003

Years Were Longer 1.3bln Years ago: Chinese Scientists

People who complain that there aren't enough hours in the day might have preferred to live 1.3 billion years ago.

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People who complain that there aren't enough hours in the day might have preferred to live 1.3 billion years ago.

At that time, according to the latest research by a group of Chinese scientists, there were 15 hours in one day, 42 days in a month, and 13 to 14 months, or more than 540 days, in a year.

The finding was obtained through a five-year systematic study of stromatolite samples, known as "stone with memory", by several researchers with the Tianjin geology and minerals research institute under the China Geological Survey Bureau.

Stromatolite mainly consists of the fossil of blue algae, which,rich in chlorophyll, was the first procaryote to emerge on the earth. Blue alga also contains a special phycobilin, which includes phycoerythrin and phycocyanin.

While phycoerythrin mainly absorbs green light, phycocyanin is particularly sensitive to orange light and, therefore, they jointly record the traces of daylight and moonlight in each day.

As a result, well preserved blue algae fossils can also contain information about the ancient climate, geology and geography from more than one billion years ago.

The stromatolite samples used during the research this time were collected from a section of Yanshan mountain in Jixian county of Tianjin city in north China, where the most complete and informative stromatolite are widely acknowledged to be preserved.

According to Zhu Shixing, one of the researchers, the stromatolite of their research was formed between 2.5 billion years to 1.3 billion years ago and contains blue alga fossil as thick as 3,336 meters.

Starting from 1998, Zhu and his colleagues began to collect stromatolite samples containing blue algae fossils, which were finally sliced into more than 2,000 ultra-thin pieces.

Under a high-power microscope, the growth trace of blue algae can be clearly seen: in daylight, it grew upright and the growth layer was thick and transparent; while in moonlight, the blue algae grew horizontally, and the growth layer turned thin and gray.The two different traces thus make up a complete daily growth layer.

Further research backed by high technologies and geomagnetism, petrosus, paleoclimatology and paleotemperature knowledge indicatethat the blue algae fossil has three rhythms, namely a daily, monthly and yearly rhythm.

An in-depth study of the microstructure of the stromatolite showed that the daily rhythm is represented by the basic layer, which is made up of a gray layer 0.01 mm to 0.05 mm thick and another transparent layer 0.3 mm to 0.8 mm thick.

Regularly, some 42 basic layers would form a group, which is the monthly rhythm, and some 13 to 14 groups would regularly form a band generally 2 cm to 8 cm thick, which is the yearly rhythm.

According to Zhu Shixing, the research result is particularly significant in that it helps to provide time coordinates for understanding the evolution of the earth and even the entire solarsystem.

The earth was formed about 4.7 billion years ago, and the speedof its rotation is believed to have gradually slowed. However, no scientific evidence proving this had previously been discovered.

Another important aspect it carries is that it has laid a basic foundation for the formation of a global stromatolite timepiece model, a brand-new scientific branch pursued by both Chinese and foreign scientists.

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