There are two different type of sources of information about the Interior. The first one is indirect information, which means that they show data in a way that gives us an idea about the Interior, but they don’t give direct measurements. These sources are useful in determining what might be inside our planet. The other type is direct measurements. These measurements were only made very recently and there are still some uncertainties, since these accounts use new techniques to get the data.
1. Direct Sources:
Direct or primary sources provide information about the topic under consideration which they possess. These sources yield an evidential decision as they can be checked and evaluated as original, raw data.
Scientists have taken up a number of projects to penetrate deeper depths to explore the conditions in the crustal portions.
Example- Scientists world over are working on two major projects such as “Deep Ocean Drilling Project” and “Integrated Ocean Drilling Project”.
2. Indirect Sources:
We know through the mining activity that temperature and pressure increase with the increasing distance from the surface towards the interior in deeper depths.
Moreover, it is also known that the density of the material also increases with depth. It is possible to find the rate of change of these characteristics.
Knowing the total thickness of the earth, scientists have estimated the values of temperature, pressure and the density of materials at different depths.
Another source of information are the meteors that at times reach the earth.
The other indirect sources include gravitation, magnetic field, and seismic activity.
The reading of the gravity at different places is influenced by many other factors. These readings differ from the expected values. Such a difference is called gravity anomaly.
Gravity anomalies give us information about the distribution of mass of the material in the crust of the earth. Seismic activity is one of the most important sources of information about the interior of the earth.
