It says the plate is moving, but why do you believe it? The answer is actually hidden in stone. The ancient magnetism is organized in the direction of iron ore particles in the rocks, turning the fact that the continent was connected from pure speculation to data-supported hammersBlock constructThe most theoretical chain of evidence。
How did ancient magnetism grow out of the rocks
In the 1880s, physicists noted that magnetic and iron ore particles would follow the direction of the geomagnetic field at the time when the rocks cooled, equivalent to a time stamp with stones. But really turning this magnetic clock into a quantitative tool, it was only in the 1950s that ancient magnetism evolved from a geology marginal subject to an independent discipline, with its own measurement standards, databases and peer-reviewed journals。
The early method is rough, a rock cuts a thin piece, and the remaining magnetic direction is measured by magnetic force, so the precision is a bit of a bit of a bit. When the gas-phase rotation magnetometer spread in the 1970s, sensitivity was raised from a negative of 10 to a negative of 6 per metre by a negative of 8 per metre and the same sample was capable of repeated detection of damage. When the amount of data comes up, the global ancient magnetic map is actually drawn, and the global coverage of the global magnetism is created。
Why would an iron particle be a compass
When magma drops from more than 700 degrees to less than half a mile (about 580°c in magnetite) the iron oxide particles will stand in the direction of the magnetic field, frozen in cyngrella, which is called thermal residual magnetism. Sedimentary rock is slower, with particles taken down in the field of geomagnetic fields after sedimentation with magnetic minerals, and then locked in the direction after hundreds of years of pressure. Both rocks record the same thing。
But when evidence is used, there are two premises: a sufficient amount of magnetic minerals, which are formed without being erased by high temperatures or chemical erosion. Therefore, researchers have given priority to the selection of basalt and ansan rock, avoiding old rock layers that have experienced regional deterioration. If a sample has a complex heat history, the direction to be measured may be a false memory and the data must be used only after a gradual demagnetic experiment to confirm the main magnetic orientation。
How do you spell the continent back
Linking the ancient magnetic poles of rocks of different ages in the same area over time is a polar shift curve. If magnetic poles run on their own, europe and north america should have a completely different curve. But it is the continent itself, not the magnetic pole, that actually moves, as the two curves are condensed together at a certain angle. This discovery deprived the magnetic polar drift hypothesis of space and continental drift became a quantifiable scientific problem。
The conclusion that the magnetic pole was not drifting was repeatedly validated by multinational teams using independent data around 1968, essentially blocking the interpretation space where the magnetic pole ran on its own. Since then, the continental drift from the 1912 weignana book, which had been mocked for decades by geology, to a geological fact supported by quantitative data, has led to a real tectonic theory。
Who saw it first
In 1905, french physicist briner detected a set of remaining magnetic direction opposite the modern magnetic field in the volcanoes of ofne, but he did not pursue it further. In 1929, after taking samples of basalts from different ages in japan and china’s north-east system, the japanese matsuyama ki-van, after queuing by geological age, found that polarity was indeed positive and negative, and that the geomagnetic reversal was considered a real phenomenon rather than a measurement error。
It was cox and del who did it between 1958 and 1961 that really turned the clock around. The fact that the two men are running through the united states, south america and africa, and that they rank hundreds of thousands to billions of years of magnetic polarity in a global calendar, both provides a year-by-year tool for geo-scientific science independent of the year of radioactivity and leaves a polar comparison for later interpretation of the seafloor magnetic strip。
What about the bottom zebra
In the aftermath of the second world war, the submarine magnetography was opened, and matthews, wan and molly made a profile of the data on both sides of the mid-atlantic ridge and found that the magnetic anomaly strip was symmetrical, like zebra strips, and space was symmetrical. The same belt is as far from the mid-ridge as the eastern ridge, suggesting that the new crust is indeed pushed from the mid-ridge to both sides at an annual rate of about 2 to 5 centimetres, which is consistent with the heat flow of the mid-ocean ridge and seismic distribution data。
A question was raised as to whether the strip could be explained by different types of rock. The answer is no: the rock of the ocean floor is clean and has no space. The only variable is whether the magnetic pole is positive or negative when the rock is formed. In 1963, the seafloor expansion model officially proposed that the plate structure be upgraded from a hypothesis to a theory with direct observation evidence and that the entire geological pattern be completely rewritten。
What are ancient magnetism still working on
Now ancient magnetism has passed the stage of proof that the plate is moving, how fast and how to turn. Magnetic anomalies from high-precision vessels, combined with satellite gravity data, can reverse the average annual rate of movement of the large plates over the past 20 to 300 million years, with precision at zero millimeters per year. The relative rotation angles of antarctica and australia have also been re-readed with ancient magnetic data and are largely in line with gps measurements。
Outside the solar system, martian insight and curiosity brought back magnetic rock data that showed that, four billion years ago, mars had a global geomagnetic field, which later became so cold that it could no longer drive a convection, that the magnetic field was completely extinguished and the surface was hit by more asteroids that did not preserve the atmosphere and liquid water like the earth. The ancient magnetic system has moved from earth to another planet。
You're on top of this land 200 million years ago. Have you checked the ancient geographical coordinates of your city? Welcome to the comment section, where you belong, where you belong 200 million years ago, probably today. If you think it's useful, just say it to your friend who's as curious as it is。
