Answer:
Sea-floor spreading occurs in the oceanic ridges. In there, volcanic activity, together with the gradual movement of the bottom, form new oceanic crust. This allows a better understanding of the continental drift explained by the theory of plate tectonics.
The greatest evidence for Sea-floor spreading is the oceanic trenches, the oceanic ridges, the magma protruding to the surface and the new seafloor.
In previous theories, continents were assumed to be transported across the sea. Harry Hess, in the 1960s, proposed the idea that the seabed itself moves as it expands from a central point. The theory is now accepted, and the phenomenon is thought to be caused by convection currents in the upper layer of the mantle.
Answer:
Higher percentage of runoff water is absorbed by the vegetation whereas 100 % of water runoff on the roofed area.
Explanation:
Higher percentage of runoff water is absorbed by the vegetation and very little amount of runoff water is received on the end of vegetative cover while on the other hand, 100 percent of precipitation water runoff on the surface of roofed or paved area because no water is absorbed by the roof due to its solid surface. The percentage of runoff depends on the factors such as rainfall intensity, slope, soil water storage capacity, and infiltration rate.
<h2><u>Q</u><u>u</u><u>e</u><u>s</u><u>t</u><u>i</u><u>o</u><u>n</u>:-</h2>
The speed of a wave is 40 m/s. If the wavelength is 80 centimeters, what is the frequency of the wave ?
<h2><u>A</u><u>n</u><u>s</u><u>w</u><u>e</u><u>r</u>:-</h2>
<h3>Given:-</h3>
Velocity (V) = 40 m/s
Wavelength
= 80 cm = 0.8 m
<h3>To Find:-</h3>
The frequency (F) of the wave.
<h2>Solution:-</h2>
We know,

40 = F × 0.8
F = 
F = 50
<h3>The frequency of the wave is <u>5</u><u>0</u><u> </u><u>H</u><u>z</u>. [Answer]</h3>
Echo sounding is the key method scientists use to map,uses sound waves bounced off the ocean bottom.