Rock Layers Absolute Age Relative Age Law of Superposition Fault

Who Dunit? Someone took the last cookie in the cookie jar last night. The last person to leave the scene is the culprit. Who was it? Clues The butler walks to work The handyman rides a bike The cook rides a motorcycle The maid drives a car The nephew has a seeing-eye dog

Who Dunit?

Objectives 8.E.2 - Understand the history of Earth and its life forms based on evidence of change recorded in fossil records and landforms. What to expect this unit?? 2 quizzes – 3/11 & 3/18 1 test – 3/22 Project

Types of Rocks (review) Igneous Rock (formed when magma cools) Metamorphic Rock (other rock types transformed by heat and pressure) Sedimentary Rock (rock formed from minerals deposited near bodies of water; forms rock layers)

Relative Age vs. Absolute Age The age based on compared position relative to other rocks – applies to both sedimentary and igneous rocks Absolute Age The number of years since the rock has formed based on radioactive decay of atoms in minerals in Igneous rock and some metamorphic rock

Half-Life the time taken for the radioactivity of a specified isotope to fall to half its original value.

Law of Superposition In horizontal layers of sedimentary rocks, the oldest layer is at the bottom. Each layer above is younger than the layers below it.

Law of Superposition Which layer is the oldest? Which layer is the youngest?

Faults a break or crack along which rocks move. Sometimes an igneous intrusion or fault will cut across or into the rock layers. The intrusion or fault will always be younger than the rocks being intruded or displaced.

Principle of Cross-cutting Intrusion: is any formation of intrusive igneous rock; rock formed from magma that cools and solidifies within the crust of the planet. During some plate movement, igneous rock forms in the process.

Unconformity Erosion causes new rock layers to meet older rock layers. This leads to a “gap in the geologic record” (missing rocks layers and fossils).

Principle of Superposition

Principle of Superposition Number the events below in the order they occurred in time, 1-9 __ earthquake __ deposit D __ deposit B __ deposit G __ intrusive lava __ rocky deposit R __ river cuts through __ deposit E __ deposit A

Video While watching the video answer – How does the Grand Canyon form and what is the evidence to support this? https://www.youtube.com/watch?v=YgE-dSx-fPc