Topic 3 Notes
Original horizontality- sedimentary rocks and some igneous rocks (extrusions
like lava flows) form in flat horizontal layers
Strata- name for layers of rock
Stratigraphy – study of the layers of rock
Deformed strata- strata that is no longer horizontal, the layers have been disturbed
Law of Superposition- oldest strata is on bottom and youngest on top
Types of Deformed strata1. Folded: (bend) by compressional forces, syncline (smile) and anticline
(frown)
2. Tilted: uplift or subsidence, strata is at an angle
3. Faulted: crack or break in the strata with displacement (they have
moved)
types of fault:
reverse fault- caused by
compressional forces (pushing
together)
normal fault- caused by
tensional forces (pulling apart)
transform fault- strike-slip
fault, lateral fault, caused by
shearing forces (sliding past
each other)
thrust fault- during mountain
building at convergent
boundaries, piece gets pushed
up on top of other continent
down fault- during rifting at
divergent boundaries
Displaced fossils – fossils that are found in locations where they do not belong
Uplift- the strata is raised up, ex. marine fossils found in the mountains
Subsidence- the strata sinks, ex. Land derived or shallow ocean fossils found
in deeper ocean
Passive margin basin- shallow basin where sediment is deposited, not at a plate
boundary, the crust subsides
Isostacy- lithosphere is in a state of equilibrium; old crust is destroyed, new is
formed;
Isostatic Rebound- the crust rises from the relief of weight, like the
Adirondacks
Orogeny- mountain building event, page 9 ESRT – ex) Grenville – 1.1 billion
years ago, created the Adirondack Mtns.
Plate tectonics – concept that Earth’s crust is changing by continental drift, seafloor spreading, and rifting
Evidence for sea floor spreading/ continental drift:
o Continents fit like a puzzle
o correlate fossils between continents (correlate means match up)
o correlate plant and animals
o animal isolation
o glacial action
o correlate rocks and minerals
o magnetic pole reversals
o age of oceanic crust in relation to the spreading ridge
Types of plate boundaries:
Divergent: (move apart)
c.c.-c.c., o.c.-o.c.
Convergent:(move toward each other)
o.c.-o.c., o.c.-c.c., c.c.-c.c.
Transform:(slide past each other)
c.c.-c.c. = San Andreas Fault