The theory of plate tectonicsThe outer layer of the Earth’s crust – the Lithosphere is not acontinuous structure but is split a little like the cracked shell on a hardboiled egg:The result is a series of plates floating on the hot mantle beneath.Heat in the mantle creates convection currentsthat cause theplates to move. Plate margins exist where the plates meet.The history of the Earth’s plates – see alsoThe beginning of time
Map – plates and continents of the World – today.
Plate Margins – where plates meetEarthquakes and volcanoes (evidence of unrest in the Earth), helplocate the edges of plates known as plate margins or boundaries.Take for example the ‘Ring of Fire’ around the Pacific. Volcano’s can bejoined together using a ‘dot to dot’ technique. The pattern that followsexactly matches known plate margins.
Different types of plate margin and how they contribute to the formationand deformationof rocks.As plates move; they canpush together ormove apart.1. Moving apart – CONSTRUCTIVE, e.g. Atlantic mid-ocean ridge.
The floor of the Atlantic Ocean is widening as plates are moving apart.