Physical Geology Laboratory

Tuesday

Tom Burbinetomburbine@astro.umass.edu

Course

• Course Website:– http://blogs.umass.edu/tburbine/

• Textbook:– Laboratory Manual in Physical Geology, 8th Edition (2009)

Busch• You also will need a calculator that you will bring to class.

Virtual office hours

• You can IM me at tomburbine on AOL

• Student: and who are u? lolStudent: u gotta answer cuz i asked first both timestomburbine: why r u Iming meStudent: cuz u added my sn for some reason so i wana know whytomburbine: sn?Student: screen name? Student: loltomburbine: no I didntStudent: ok..tomburbine: do u live in massachusetts?Student: do u?tomburbine: do u live in cambridge?Student: notomburbine: is it snowing?Student: yeatomburbine: do u have a xnga?Student: no joke who the f**k are ya?Student: yes i do live in MAtomburbine: i never heard of u until u Imed meStudent: then how the h**l did u know i lived in MA?

• Student: and yes i do go to umasstomburbine: r u in astronomy 100Student: how do u know all this?tomburbine: because I am the professorStudent: OHHHHH OOOPS!tomburbine: i think u must have added meStudent: omg loltomburbine: and then forgot who I wasStudent: ya i didStudent: sorry for all that tomburbine: my name is my screen nametomburbine: seem familar nowStudent: didnt mean to use language but it happenedtomburbine: no problemtomburbine: funnyStudent: hehtomburbine: i actually dont know who u rStudent: good thing we got an exta 2 days for the hwtomburbine: yestomburbine: u can Im me anytimetomburbine: and Student: ill tell ya if u promiss not to fail metomburbine: I cant add my name to ur aimtomburbine: only u cantomburbine: i am fine not knowingStudent: okStudent: well i have to go ill cya on thursday. take caretomburbine: bye!

Plate Tectonics

• Plate Tectonics describes the large scale motions of Earth's lithosphere

Continental Drift Hypothesis

• Alfred Wegener (1915) thought that all continents were part of a single supercontinent called Pangea

Pangea

• Pangea - One large supercontinent

http://geology.csupomona.edu/drjessey/class/Gsc101/pangea.gif

Principles of Plate Tectonics

1. The surface of the Earth is composed of lithospheric plates that are in constant motion.

2. The plates move in response to plastic flow in the athenosphere.

3. Motion in the asthenosphere is caused by convection driven by the Earth’s internal heat.

4. The internal heat comes from radioactive decay and the latent heat from the Earth’s formation.

Plate Tectonics

• Earth has a thin rigid lithosphere that is underlain by a plastic asthenosphere

• Seafloor crust is created along mid-ocean ridges where magma upwells from the mantle

• Ocean basins are generally younger than continents

• Seaflloor spreads until it encounters a trench and descends back into the mantle

• Rocks can deform and flow

• Easier for rock to deform and flow when it is warmer

Heating of Planet

Lithosphere

• Lithosphere is a planet’s outer layer of cool and relatively rigid rock

• Asthenosphere is the region in the upper mantle characterized by low-density, semiplastic (or partially molten) rock material chemically similar to the overlying lithosphere

Three Types of Plate Tectonic Boundaries• Divergent – plates move apart, space is filled with

molten magma

• Convergent – plates collide

• Transform – plates slide horizontally past each other

Divergent plate boundary

Convergent Plate Boundary

Transform Boundaries

Magma

• Magma – a mixture of molten rock, volatiles, and solids

• Lava is magma that erupts on the surface

Melting Point

• Melting point – temperature that crystals of a given mineral melt

• All minerals have different melting points

• Partial melting – part of a rock melts before another rock

Geothermal Gradient• Increasing temperature with depth

Pressure• Pressure is force per unit area

• Pressure increases as you go deeper in Earth because of the weight of the surrounding rock

Pressure

• Raising the confining pressure increases the melting point of the rock

• Lowering the confining pressure lowers the melting point of a rock

P-T (pressure-temperature) diagram

Hot Spots

Any Questions?