PLATE TECTONICS HISTORY
- Scientific theory explaining the movement of Alfred Wegener (1880-1930)
the earth’s lithospheric plates. - Continental Drift Theory – the movement and
- These plates float on the semi-fluid distribution of the continents. This started the
stenosphere beneath them causing formation of the Plate Tectonics Theory.
continental drift, earthquakes, and the - 200 million years ago, the continents are not
formation of mountain ranges and oceanic that drifted compare today.
trenches. - PANGAEA “All the Earth” -> supercontinent
- The interaction of these plates occurs in Pan = all, Gaea = Earth
boundaries that can be divergent,
convergent or transform shaping the earth’s Plate Tectonics Theory
surface over millions of years. - The earth’s outer mechanical layer, the
lithosphere, is divided into large continent
sized plates that are constantly moving.
2 TYPES OF LAYERS
- The movement is measured 1-2 inches per
1. Compositional Layers – classified based on year.
composition - The earth is constantly making new
- Crust (10-70 km) lithosphere.
- Mantle - The earthquake happens in the same area.
- Core (2900 km) Happens along plate boundaries. They are
manifestation for these movement.
2. Mechanical Layers – used in order to - Discovery of many fossils in random areas.
understand plate tectonics
- Lithosphere (10-200 km) – outer most layer,
composed of the entire crust plus the EVIDENCE
topmost portion of the mantle. Rigid and 1. DIKES – heated magma rises up through
solid. cracks in the oceanic crust.
- Asthenosphere (660 km) – where the plates - New rock/land is created new materials
are floating on. Semi solid and semi liquid = - Constant creation of new land masses
FLUID, why? Because it’s extremely hot. Has reforming and reshaping.
the greatest impact on the plates. These
plates are in a constant movement.
2. EARTHQUAKES – earthquakes/volcanic
- Mesosphere (2900 km) – these are solid
activity happened in the same location as the
because the pressure is greater compared to
plate boundaries.
Asthenosphere. NOT AS INFLUENTIAL AS
ASTHENOSPHERE BUT DEEPER. Pressure is
pushing things down the mantle. 3. FOSSILS – tropical animal and plats species
- Outer Core (5, 100 km) – 2nd deepest layer. have been found in Africa and other places on
Liquid, greater fluidity than asthenosphere earth that are less tropical which proves that
due to temperature. Mainly made out of the continents are moving. One of the most
metals, rocks. Just imagine lava, and this is significant evidences.
mainly made up of it.
- Inner Core – solid because of high pressure
despite being the hottest layer which is the
HOW IT ALL WORKS
source of heat that will affect Asthenosphere 1. Convergent Boundaries
that will then affect the Lithosphere. - Ring of Fire -> Subduction Zone
- Mt. Everest increases 1-2 inches every year
- Earthquakes can be experienced here
2. Transform Boundaries
- Earthquakes -> San Andreas Fault
- Pressure builds up as plates slide past each
other until pressure is released.
- Creates cracks/faults
3. Divergent Boundaries
- Continental: space widen and become a large
crack/rift East African Great Rift Valley
- Oceanic: oozing of magma since the oceanic
plate is much thinner than the continental
plate Seafloor spreading Mid-Atlantic
Bridge
RELATIVE AND ABSOLUTE DATING
Relative Dating – places events or rocks in order of
their position or relationships to other layers without
specifying the exact age.
- Absolute Dating – provides precise age
using methods like radiometric dating to
determine the actual time a rock or time
occur.
RELATIVE DATING
