Name________________________
Guide Notes Relative Dating
Relative Dating- is used to arrange__________________ ___________, and the
rocks they leave behind, in a _____________. The method of reading the order is
called _____________________ (layers of rock are called ____________). Relative
dating does not provide actual _______________ _______/_____ for the rocks.
Relative Age - is the “age” of a _______________ or _____________ compared to
the ages of other rocks or strata.
Principle of Superposition - as ________________ rocks form, they are deposited
on ____________ rock layers. Principle of Superposition in undisturbed layers,
the oldest is on the ___________ and ___________ layers are younger.
Principle of Original Horizontality - The law states that layers of sediment were
originally _______________ horizontally under the action of gravity.
Principal of Fossil Succession- Also known as the ___________________
_________________, is based on the observation that sedimentary rock strata
contain fossilized flora (plants) and fauna (animals), and that these
_________________ succeed each other vertically in a specific, reliable order that
can be identified over wide horizontal distances.
Principle of Cross-Cutting Relationships- An igneous/metamorphic rock,
____________, or other _______________ must be younger than any rock across
which it cuts.
Uniformitarianism- is the idea that the ___________ occurring on earth today are
____________ to those that occurred in the past. Uniformitarianism basically says
“The ______________ is the key to the ________________.” Uniformitarianism is
the idea that geological features formed _____________ over
____________periods of time. Uniformitarianism claims the Earth is
___________________years old.
CROSS-CUTTING RELATIONSHIPS
Extrusions- are _____________ rocks layers that form on the surface when
_________________ hardens. Extrusions are always _____________________
than the layers over which they form.
Intrusions are igneous rocks that form when _______________ pushes up into
rock layers. Intrusions are always ______________ than the rock layers they
invade.
Faults- are _______________ in the earth’s crust. A fault is always
________________ than the rock it cuts through.
Folds- occur when rock layers are _________________ together and
_____________ or ______________.
Unconformities- are gaps in the rock sequence (caused by the ________________
of rock layers).
Angular Unconformity- occur when rock layers are ______________ or
_______________, and then worn down by erosion and weathering.
Disconformities- are ___________________ created when erosion occurs on an
overlying rock layer.
Nonconformity- are formed when ________________ rock overlays igneous or
metamorphic rocks.
INDEX FOSSILS AND CORRELATION
Correlation- is using rock and fossil evidence to ____ _________ dating at
different ____________________.
Index Fossils are used for _______________ the rock _______________ in which
they are found. Index Fossils are species that were _________________ all over
the earth, but existed for shorter periods of time.