One reason is that the plates float on a hot boiling mentle. when the heat rises and the mentle expands the plates above it also moves.
the other reason is that the plates themselves move.plates have warmer inner sides that tend to rise. and colder outer side that tends to sink. this tug of war between the hotter and colder sides of the plate also helps them move.
Triangular trade refers to the three legs of the trade system. -The first leg was the of trade was from Europe to Africa where goods were exchanged for slaves. -The second or middleleg of the trade was the transportation of slaves to the Americas
