Section 5.2 – Convection & the Mantle Radiation = Transfer of energy (heat) through open space. Conduction = Heat transfer within a material or between materials that are touching. Convection = Heat transfer by the movement of currents within a fluid.

Convection Currents = Set in motion by the heating & cooling of a fluid, changes in fluid’s density, and the force of gravity combined. Within the mantle, heat from the core & the mantle itself causes convection currents.

Section 5.3 – Drifting Continents Alfred Wegener Said that all continents were once joined together in a single landmass & have since drifted apart. His theory has come to be known as “continental drift.” “Pangaea” was the supercontinent the continents once formed around 300 million years ago. He gathered evidence from land features, fossils, and climate change from different continents to support his theory. Published “The Origin of Continents & Oceans.”

Evidence from Land Features Mountain ranges, coal deposits, & other features on the continents line up / match up with each other.

Evidence from Fossils Fossils of the same plant and/or animals have been found in places separated by oceans. Plants & large reptiles can’t swim!!

Evidence from Climate Fossils of tropical plants have been found on islands in the Arctic Ocean. Scratches in rocks in southern Africa show that glaciers once covered the land.

Wegener’s Theory Rejected… At first. Theory was initially rejected because he could not explain what force was causing the push/pull of the continents. Other geologists said mountains are formed by the cooling & shrinking of the Earth – like the “skin of a dried-up apple.” Wegener theorized that because mountains occur in narrow bands along the edges of continents that their edges must crumple together when they collide – forming the mountains. His theories were eventually determined to be true!