DO NOW 1.What is the Geologic Time Scale based on? 2.What 2 events characterize the Cenozoic Era? 3.What 2 events characterize the Quaternary Period? 4.What are the two types of crust and how are they different? 5.Describe the consistency of the upper portions of Earth’s mantle

Unit 1- Earth Systems and Resources Plate Tectonics

AIM: What are tectonic plates and how have they moved over time?

Lithosphere The solid, outer part of Earth Consists of the crust, and the uppermost mantle

Asthenosphere Upper portion of the mantle that has a “plastic-like” consistency

Asthenosphere – “plastic like” Lithosphere – Solid

Earth’s lithosphere is divided into several large pieces called “tectonic plates”

The plates are constantly moving, a phenomena known as “plate tectonics” – 2-5 cm a year The plates (lithosphere) are able to glide on the plastic-like portion of the mantle, known as the asthenosphere

The lithosphere glides on the asthenosphere Slow creeping motion of the mantle is caused by convection currents, carrying heat from Earth’s interior to the surface

Convection currents in the asthenosphere move plates in the lithosphere

Theory of Plate Tectonics.. The theory of plate tectonics arose out of 2 separation geological observations: – The continental drift theory – The seafloor spreading theory

Continental Drift Alfred Wegner proposed that all present-day continents originally form one land-mass- Pangaea Wegner proposed that this supercontinent began to break up 200 million years ago

1.Fossilized tropical plants were found in Greendland’s icecaps 2.Tropical regions on some continents had polar climates in the past 3.The continents fit together like puzzle pieces 4.Similarities existed in rocks between the east coast of North and South America and the west coasts of Africa and Europe 5.Fossils of extinct land animals were found on separated land masses

Tropical plants fossils in cold climates Continents fit like a puzzle Coasts of different continents have same rocks Fossils of extinct species found on separated landmasses

Plate Tectonics Earth’s lithosphere is divided into 8 major plates Divisions between plates are called boundaries

Plates interact at their boundaries There are 3 types of plate boundaries – Transform boundaries – Divergent boundaries – Convergent boundaries

Transform Boundaries Two plates slide past each other

Divergent Boundaries Two plates slide apart from each other

Convergent Boundaries Two plates slide towards each other If an oceanic plate and a continental plate are colliding, the oceanic plate will slide under the continental plate – The oceanic plate is more dense – This is called SUBDUCTION