Fossils and Faults Activity Background – Stress The movement of Earth’s plates creates enormous forces that squeeze or pull the rock in the crust. Since the outer part of the Earth crust is relatively cold, when it is stressed it tends to break. Any force that acts on rock to change its shape or volume is called _______________. Stress adds energy to the rock. The energy is stored in the rock until it changes shape or breaks. There are 3 basic types of stress acting upon the Earth’s crust: tension, compression and shearing. ________________pulls on the crust, stretching rock so that it becomes thinner in the middle. *We call this a ___________ boundary when discussing plate tectonics. _____________________ Fault ______________________squeezes rock until it folds or breaks. *We call this a _________________________ boundary when discussing plate tectonics. _____________________ Fault ______________________ pushes a mass of rock in two opposite directions *We call this a _______________boundary when discussing plate tectonics._____________________ Fault Background - Faults When enough stress builds up in rock, the rock breaks, creating a fault. These breaks are called ____________________________. Most faults occur along plate boundaries, where the forces of plate motion push or pull the crust so much that the crust breaks. There are three main types of faults: normal faults, reverse faults, and strike-slip faults. The most obvious result of movement along a fault is an _____________________. Earthquakes tend to happen along the boundaries between plates ________________ causes a normal fault. In a _____________________ ___________, the fault is at an angle, and one block of rock lies above the fault while the other block lies below the fault. The block of rock that lies above is called the _____________________________ The rock that lies below is called the ________________________________. _____________________ causes reverse faults. A ____________________ fault has the same structure as a normal fault, but the blocks move in the opposite direction. ____________________creates strike-slip faults. In a _______________- _______________ fault, the rocks on either side of the fault slip past each sideways, with little up or down motion. Background - Fossils and Superposition The ______________ ______ ______________________ states that in undisturbed rock layers the oldest rock is on the bottom and the youngest is on the top. This makes it simple to determine the relative age of fossils in the different layers of rock. The rock layers, however, are often disturbed (mixed) because of plate motion. Faulting and folding take old rock and push it on top of young rock. Over millions of years, the forces of plate movement can change a flat plain into landforms such as anticlines and synclines, folded mountains, fault-block mountains, and plateaus. A fold in rock that bends upward into an arch is an ________________________. A fold in rock that bends _________________ to form a ________________ is a _________________. Anticlines and synclines are found on many parts of the Earth’s surface where _____________________ forces have folded the crust. Plate movements and stress also create reverse, normal, strike slip and thrust faults. The constantly shifting plates make it difficult to date the age of the Earth’s rocks. A paleontologist (scientist that studies fossils) has to know geology to read the fossil record of life on earth. Directions 1. Color the fossils and faults model according to the color key provided. 2. Cut out the fossils and faults model and form into a box with the surface features on the top. 3. Use the shaded tabs to tape the corners together. 4. Carefully cut the model in half along the dotted line. 5. Cut out and tape the fault face pieces to the open fault face of the two halves. 6. Label the two halves as hanging wall and footwall as shown below. 7. Use the model to answer the questions. .