The theory of continental drift was modified based on the new observations to become the theory of plate tectonics. The theory of continental drift was proven false, and the law of plate tectonics took its place.

Fossil Evidence One type of evidence that strongly supported the Theory of Continental Drift is the fossil record. Fossils of similar types of plants and animals in rocks of a similar age have been found on the shores of different continents, suggesting that the continents were once joined.

What is the continental drift hypothesis? Proposed by Alfred Wegener, it states that Earth’s continents have moved slowly to their current locations. All the continents were once connected as one landmass that broke apart 250 million years ago. This one landmass is called “Pangea,” meaning “all land.”

Continental convergent plate boundaries

There are three types of convergent plate boundaries: oceanic-oceanic boundaries, oceanic-continental boundaries, and continental-continental boundaries.

Divergent boundaries — where new crust is generated as the plates pull away from each other. Convergent boundaries — where crust is destroyed as one plate dives under another.

Examples of Convergent Boundaries The West Coast of South America is a convergent boundary between the Nazca Plate and the South American Plate. The collision of this oceanic and continental plate was how the Andes Mountains were formed. Convergent boundaries can also form islands.

A divergent plate boundary often forms a mountain chain known as a ridge. This feature forms as magma escapes into the space between the spreading tectonic plates.

mid-ocean ridge system

What is the main cause of uplift during a continental collision? enters a subduction zone, where it is scraped off the subducting plate and added to the continent. a wedge-shaped zone of faults, folds, and metamorphosed rocks formed along the upper parts of a subduction zone as material is scraped off.

Examples of ocean-continent convergent boundaries are subduction of the Nazca Plate under South America (which has created the Andes Mountains and the Peru Trench) and subduction of the Juan de Fuca Plate under North America (creating the Cascade Range).

Ancient plates and cratons Cratons are the oldest and most stable parts of the continental lithosphere and shields are the exposed area of a craton(s).

The plates are always moving and interacting in a process called plate tectonics. The continents are still moving today. Some of the most dynamic sites of tectonic activity are seafloor spreading zones and giant rift valleys.