Contacts between sedentary and nomad peoples<span> resulted in trade, tribute payments</span>
A coral island is a type of island formed from coral detritus and associated organic material. They occur in tropical and sub-tropical areas. <span>A group of coral islands, or an atoll, form as underwater volcanoes grow and get closer to the surface, effectively raising the sea floor. Hope this answers the question.</span>
Canada has a lot of natural resources -this is one of the reasons why it's in such a strong position. Another reason why it's so strong is that it has ports on both the Atlantic Coast and the Pacific coast - so it can trade with both Europe, Africa and Asia.
Answer:
Earth's surface is the major direct source of heat for the troposphere, but nearly all of that heat comes originally from the sun. Earth's surface absorbs sunlight and radiates it back into the atmosphere as heat.