The statement is true.
As weird as it may sound, helium was indeed first discovered on the Sun, and after some time on Earth. The first evidence of helium was observed on August 18 1868, as a bright yellow line with a wavelength of 587.49 nanometers in the spectrum of the Sun's chromosphere. This line has been detected by a French astronomer by the name of Jules Janssen during a total solar eclipse in Gantur, India.
In geology, a graded<span> bed is one </span>characterized by<span> a systematic change in grain or clast size from one side of the bed to the other. Most commonly this takes the form of normal grading, with coarser sediments at the base, which grade upward into progressively finer ones.</span>
Answer:
1. Viscous Drag
2. Slab-Pull Force
3. Ridge-Push Force
Explanation:
The three factors that drive plate motion in the asthenosphere are as follows:
1. Viscous Drag
2. Slab-Pull Force
3. Ridge-Push Force
Asthenosphere is the upper layer of the earth's mantle. This layer lies below the lithosphere at depths between approximately 80 and 200 km below the surface.
LAB refers to the lithosphere–asthenosphere boundary.
