Classify each planet as an inner planet or an outer planet.
over the last 250 million years, the world changed from a single land mass to a number of different continents. one reason for the change is expanding ocean floors. what causes ocean floors to expand?

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other