Describe why echo sounding is a better method of mapping the ocean floor than the lead weight on a line

The lines marked by the letters a, b, and c on the map above represent a. chains of volcanoes b. earthquake fault lines c. thin strips of heavy forests d. major rivers that flow from north to south

The mantle is made up of which structural zones?

Which of the following is a measure of the amount of light a star directly emits? a. luminosity b. wavelength c. brightness d. intensity