Earths History (1).pdf

PLATE BOUNDARIES 1. CONVERGENT 2. DIVERGENT 3. TRANSFORM CONVERGENT BOUNDARIES Plates move towards each other, leading to subduction, mountain building, or volcanic activity. DIVERGENT BOUNDARIES Plates move apart, creating new oceanic crust (e.g., Mid-Atlantic Ridge). TRA...

PLATE BOUNDARIES 1. CONVERGENT 2. DIVERGENT 3. TRANSFORM CONVERGENT BOUNDARIES Plates move towards each other, leading to subduction, mountain building, or volcanic activity. DIVERGENT BOUNDARIES Plates move apart, creating new oceanic crust (e.g., Mid-Atlantic Ridge). TRANSFORM BOUNDARIES Plates slide past each other, causing earthquakes (e.g., San Andreas Fault). EARTH’S HISTORY Earth’s History Geologist are able to trace the history of the Earth with the used of relative and absolute dating. RELATIVE DATING means putting events or objects in chronological order without including actual dates or ages. BASIC PRINCIPLES ON Relative Dating 1. Law of Superposition 2. Principle of Original Horizontality 3. Principle of Cross- Cutting Relationship 4. Unconformities LAW OF SUPERPOSITION It states that in an undeformed sequence of sedimentary rock, the layers found on the top are the youngest rocks and the layers at the bottom are the oldest rocks. Nicolaus Steno PRINCIPLE OF ORIGINAL HORIZONTALITY Steno stated that an undeformed sequence of sedimentary rock is the one where the layers are still in a horizontal position. PRINCIPLE OF CROSS - CUTTING RELATIONSHIP It determines which events happened first depending on which rocks were affected. The geologic layer that cuts another is younger than the layer it cuts across. UNCONFORMITIES Conformable - rock layers that have not been interrupted. These sites represent spans of geologic time. UNCONFORMITIES geological features that represent gaps in the geological record, where rock layers are missing due to erosion or non-deposition over a period of time 3 BASIC TYPES OF UNCONFORMITIES ABSOLUTE DATING In geology or archaeology, it is the process of finding a numeric or exact age of rocks or fossils using radiometric dating. RADIOMETRIC DATING Examines the ratio of one isotope to another in rock to determine its age.  ISOTOPE Elements that have the same number of protons but different number of neutrons. Most isotopes are stable but some are unstable isotope known as radioactive/parent isotopes.  FOSSILS The remains of living organisms used in understanding the history of the Earth. Body Fossils - fossils formed from parts of an organism. Trace Fossils - give signs or clues that life was present at that time. Index Fossils - fossils used to determine the age of a rock and these are only found in rocks of particular age. GEOLOGIC TIME SCALE GEOLOGIC TIME SCALE The geological time scale is a record of the life forms and geological events in Earth’s history. PALEOZOIC ERA: ERA OF OLD LIFE - The Cambrian period - Explosion of life in the oceans - Formation of Pangaea - Age of invertebrates - Fish led to the arrival of amphibians (The end of the Paleozoic era is called the “Age of Amphibians”) TRILOBITES CEPHALOPODS MESOZOIC ERA: THE AGE OF REPTILES - Extinction of dinosaurs and few reptiles survive - Break up of Pangaea - Formation of modern ocean basins CENOZOIC ERA: THE ERA OF RECENT LIFE - Represents a small portion of the geologic time scale - Age of mammals - Humans evolved  TYPE OF TESTS: MULTIPLE CHOICE IDENTIFICATION TRUE OR FALSE ILLUSTRATING CONSTRUCTED RESPONSE