Thermal Convection, ridge push and slab pull are believed to be the
processes that cause plate tectonics to move.
Thermal convection is a process when the core of the Earth’s heat is
transferred to Earth’s surface by mantle.
Ridge push is when the mantle wells upward
due to convection and raises the edge of spreading oceanic plates. Since the
plates are higher at the spreading center, they are forced downhill because of
gravity as a result, the ocean floor is flatten.
Slab pull is the part of tectonic plates’
motion which can be accounted for through its subduction.
B. france purchased louisiana to take over mexico
The illegal smuggling caused economic hardship in the Portuguese empire. During the 8th and 9th Centuries, tobacco became the major product in the Portugal. Tobacco’s importance as a commercial product had in fact grown steadily after 1620, and by the early 1700s, the monopoly on its sale had become one of the country’s most precious sources of income.
Together with spices, tobacco became the principle item of exchange for products from the Far East and for slaves taken from the coast from the West Africa.
The greeks had victory over
marathon
salamis
and Plataea in the 5th century BCE
