The principles of stratigraphy help us understand the relative age of rock layers. When the magnetic north pole is close to the geographic north pole as it is todayit is called normal polarity. Fossils are important for working out the relative ages of sedimentary rocks. In other words, as sediment fills a depositional basins we would expect the upper most surface of the sediment to be parallel to the horizon. University of California Press Geologists have established a set of principles that can be applied to sedimentary and volcanic rocks that are exposed at the Earth's surface to determine the relative ages of geological events preserved in the rock record. Layers of rock are deposited horizontally at the bottom of a lake principle of original horizontality.
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Dating Rocks and Fossils Using Geologic Methods
Walker, M. How to Become a Primate Fossil. Multibranched relative of starfish; lives attached to the ocean bottom; some living species "sea lilies" NAME: Locally, physical characteristics of rocks can be compared and correlated. Multibranched relative of starfish; lives attached to the ocean bottom; some living species "sea lilies". Information such as index fossils or radiometric dates can be used to correlate a particular paleomagnetic reversal to a known reversal in the GPTS. Determination of the absolute age of rocks and minerals using certain radioactive isotopes.