The modern land and sea are now well distributed on the surface of the earth, becoming homes for various animals and plants to thrive. Have you ever known that in the long history of the earth, terrestrial plates have gathered and separated, constantly changing their positions. It is a traditional geological research method to infer the position changes of land plates by measuring paleomagnetic data. Professor Liu Benpei of China University of Geosciences can also know whether the land plates have been rotated by observing the growth rings of ancient plant fossils. Next, let us bring a compass and a magnifying glass, approach the plant stem fossils-wood fossils, and explore the secrets of the earth’s circle by measuring and observing the tree rings.
Find the secrets of tree growth in the northern hemisphere
In the northern hemisphere, plants all have the characteristics of growing toward the sun, showing an asymmetric growth trend of large in the south and small in the north. The center of the tree, that is, the pith of the tree, is often not in the center of the tree ring. The more the tree goes to the north, the more the tree ring center shifts to the north. The deviation of the annual ring center is precisely the tree showing the characteristics of sunny growth.
The following figure shows the tree rings in four latitude directions from left to right. For Russian pine at about 60°north latitude, the center of the tree rings is obviously biased to the north; for fir at about 45°north latitude, the tree rings show obvious asymmetric growth on both sides; the trees of Laojun Mountain, Lijiang, Yunnan at about 25°north latitude, still It can be seen that the tree rings grow asymmetrically on both sides of the tree; while the trees in the tropical rain forest area within 10° north latitude, the center of the tree rings has no obvious deviation.
Positive measurement of lone wood stump
From the figure, we know that the deviation of the tree ring center from north to south shows a growth pattern from strong to weak to no (the closer it is to the North Pole, the more it shifts). So is the direction in which tree rings grow in the sun in the northern hemisphere is due south? After measurement, we found that the positive shift of the tree rings is south to west. This is because the most prosperous time for tree growth is in the afternoon, when the sun is not in the southerly direction, but in the west-south direction, so we speculate that the maximum growth direction of trees is the west-south direction.
Positive measurement of existing trees
In order to verify the above rules, we used the existing trees located in Beijing Xiangshan Wofo Temple Bus Station (about 40°N latitude) and Jilin Huadian Forest Farm (about 43°N latitude) to carry out positive measurement of tree rings. The experimental results show that between 39° and 43° north latitude, the measured tree rings on a flat ground, unobstructed and far from the water source, face the positive direction (maximum growth direction) of 219°± 5°. And this experimental result also fully confirmed the law of tree ring center deviation.
Why choose flat ground, no shelter, and away from water sources? Because tree rings are very sensitive to external disturbance factors. Generally speaking, the gravitational growth of trees in the mountains (both the south slope and the north slope) exceeds the positive growth, which will cause the deviation of the annual ring to be inaccurate, so you can only choose flat land. In addition, if the two trees A and B block each other, the A tree is very large and it blocks the B tree, and the B tree will bypass the A tree and continue to grow toward the light. The direction of the annual ring offset is also inaccurate for the B tree. of. In addition, we found on the stumps next to the Gansu canal that all trees have a tendency to grow toward the water. Based on the above factors, we selected tree stumps that are only affected by sunlight for measurement.
Positive measurement of petrified wood
After investigating the positive direction regularity of existing trees, we discovered in-situ and upright silicified wood in the same area in the same latitude zone, and then imagined whether trees in the Jurassic period should also have the same regularity. Petrified wood is a kind of wood fossil. Hundreds of millions of years ago, trees were buried deeply in the ground for various reasons. Chemical substances around the trunks entered the trees under the action of groundwater, replacing the original wood components, retaining the shape of the trees, and forming fossil woods through petrification. Since petrified wood is often stored horizontally and upright in high ground and far away from water sources, a little attention can be used to eliminate obstructing factors during field observation. Therefore, we speculate that petrified wood stored in situ and upright also has the characteristics of sunny growth.
Plate rotation in the Jurassic period
After measuring the above petrified wood, it is found that there is a deviation between the positive data of petrified wood and the positive data of existing tree stumps. Specifically, the positive data of silicified wood in western Liaoning during the middle and late Jurassic is 237°, which is 13°～23° different from the existing 219°±5°, while the positive data of silicified wood stumps in Yanqing, Beijing in the late Jurassic It is 233.5°, which is 9.5°～19.5° from the current data. Paleomagnetic data show that the North China Plate has shifted in geological history. It has rotated from the middle and late Jurassic to the present, but how to rotate is still controversial. We observe the above data. The difference between the data in the middle and late Jurassic and the current data is 13°～23°, which indicates that the latitude of the silicified wood is higher than the current period, so a clockwise rotation occurred, and the data in the late Jurassic changed. It is small, but still 9.5°～19.5° larger than the current data, indicating that the plate continues to rotate clockwise. This conclusion verifies that the North China Plate has rotated clockwise from the middle and late Jurassic to the present, and also verifies the views of mainstream paleomagnetologists.
It is a cross-discipline of paleontology and geotectonics to verify the continuous circle of the earth by measuring the positive data of trees. It is also a cross and verification between multiple disciplines. From a small tree to positive data, it can be inferred. The theory of rotation of the earth’s plate. In fact, starting from the details of life, as long as you are good at observation, you can also explore more scientific mysteries!