<Tr> <Td> </Td> <Td> This article relies largely or entirely on a single source . Relevant discussion may be found on the talk page . Please help improve this article by introducing citations to additional sources . (January 2016) </Td> </Tr> <P> Tectonic plate interactions are of three different basic types: </P> <Ul> <Li> Divergent boundaries are areas where plates move away from each other, forming either mid-oceanic ridges or rift valleys . These are also known as constructive boundaries . </Li> <Li> Convergent boundaries are areas where plates move toward each other and collide . These are also known as compressional or destructive boundaries . <Ul> <Li> Subduction zones occur where an oceanic plate meets a continental plate and is pushed underneath it . Subduction zones are marked by oceanic trenches . The descending end of the oceanic plate melts and creates pressure in the mantle, causing volcanoes to form . </Li> <Li> Obduction occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate . This causes the oceanic plate to buckle and usually results in a new mid ocean ridge forming and turning the obduction into subduction </Li> <Li> Orogenic belts occur where two continental plates collide and push upwards to form large mountain ranges . These are also known as collision boundaries . </Li> </Ul> </Li> <Li> Transform boundaries occur when two plates grind past each other with only limited convergent or divergent activity . </Li> </Ul> <Li> Divergent boundaries are areas where plates move away from each other, forming either mid-oceanic ridges or rift valleys . These are also known as constructive boundaries . </Li>

What are the three basic tectonic plate boundaries