Earth's History Notes PDF

EARTH’S HISTORY PRINCIPLE OF ORIGINAL Prepared by: Ms. Emilou C. Aron HORIZONTALITY o All rock layers were originally Stratified Rocks...

EARTH’S HISTORY PRINCIPLE OF ORIGINAL Prepared by: Ms. Emilou C. Aron HORIZONTALITY o All rock layers were originally Stratified Rocks deposited horizontally. ARE LAYERED ROCKS FORMED DUE PRINCIPLE OF SUPERPOSITION TO THE DEPOSITION OF ITEMS SUCH o It states that each layer of AS SAND AND SILT NEAR THE sediments or rocks is piled RIVERBEDS, FORMING LAYERS ON on top of another layer, TOP OF EACH OTHER making the one on top of the Methods strata the youngest one. o RELATIVE DATING - a method While the layer at the bottom of determining the age of of the strata is the oldest. rocks in each layer by PRINCIPLE OF CROSS-CUTTING identifying the relative order of RELATIONSHIPS previous events. Relative o It states that an igneous dating can usually be intrusion is always younger established based on fossils than the rock it cuts across. o ABSOLUTE DATING - a method PRINCIPLE OF INCLUSIONS of determining the numerical o The rocks that are mixed up age of rocks using different in the formation of methods sediments is called Relative Dating inclusions. These rocks are always older than the layer of FOSSILS - Most of these life-forms are found as sediments it is embedded in. fossils, which are the remains or traces of an PRINCIPLE OF FOSSIL SUCCESSION organism from the geologic past that has been o Fossils of plants and animals preserved in sediment or rock. Without fossils, are grouped according to the scientists may not have concluded that the period of geologic time they earth has a history that long precedes appeared. Strata containing mankind. those groups of fossils are also formed during that STRATIGRAPHY - This technique assumes that particular time. the lowest layer is the oldest while the topmost layer is the youngest layer. It is one of the Absolute Dating oldest methods of relative dating BIOSTRATIGRAPHY - In this technique, the METHODS faunal deposits such as fossils of dead animals are used to establish a strategy for Radiometric dating - It determines the age of dating. It is an extended version of the the sample by measuring the amount of a stratigraphy. particular radioactive isotope present in the sample. CROSS DATING - In this method, the fossils of one layer are compared with another layer Radiometric dating - The age can be with known dating. determined by the rate of decay of that isotope. PRINCIPLES OF RELATIVE DATING Amino acid dating - The change in the protein content of a biological sample can be used to determine the age. A particular form of living being may have a defined protein content in their bodies that deteriorates with time. Dendrochronology - The number of annual growth rings of a dicot is used in this technique to determine the age of the tree Thermoluminescence - This technique determines the final period during which the object absorbs light, emitting electrons. The age is determined for the emissions. RELATIVE VS ABSOLUTE Relative Dating can be referred to as its physical aspects found in rocks, while Absolute Dating refers to the measurements taken to determine the actual time it expires.