Use this information to sequence the cards in a vertical stack of fossils in rock strata. 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. If the amount of radiation to which an object is exposed remains constant, the amount of electrons trapped in the imperfections in the crystal structure of the material will be proportional to the age of the material. Relative dating by biostratigraphy is the preferred method in paleontology and is, in some respects, more accurate. Determining the number of years that have elapsed since an event occurred or the specific time when that event occurred. Squid-like animal with coiled, chambered shell; related to modern-day Nautilus.
A fossil can be studied to determine what kind of organism it represents, how the organism lived, and how it was preserved. Many of these organisms have left their remains as fossils in sedimentary rocks. Concepts Deep time Geological history of Earth Geological time units. Geologists also use other methods - such as electron spin resonance and thermoluminescencewhich assess the effects of radioactivity on the accumulation of electrons in imperfections, or "traps," in the crystal structure of a mineral - to determine the age of the rocks or fossils. A fossil that can be used to determine the age of the strata in which it is found and to help correlate between rock units. Positively charged subatomic particles found in the nucleus of an atom radioactivity radioactive: