For example, most limestones represent marine environments, whereas, sandstones with ripple marks might indicate a shoreline habitat or a riverbed.
The Law of Superposition, which states that in an undisturbed horizontal sequence of rocks, the oldest rock layers will be on the bottom, with successively younger rocks on top of these, helps geologists correlate rock layers around the world.
This also means that fossils found in the lowest levels in a sequence of layered rocks represent the oldest record of life there.
This interactive asks you to use your knowledge of relative dating. Help us work out the relative ages of the layers of sedimentary rocks.
You need to work out the order in which rocks were formed, from youngest to oldest. Remember that younger sedimentary rocks lie on top of older ones and were horizontal when formed.
Sequencing the rock layers will show students how paleontologists use fossils to give relative dates to rock strata.
Once students begin to grasp "relative" dating, they can extend their knowledge of geologic time by exploring radiometric dating and developing a timeline of Earth's history.
These major concepts are part of the Denver Earth Science Project's "Paleontology and Dinosaurs" module written for students in grades 7-10.
The module is an integrated unit which addresses the following National Science Education Standards: *Science as Inquiry: Students develop the abilities necessary to do scientific inquiry identify questions, design and conduct scientific investigations, use appropriate tools and technologies to gather, analyze and interpret data, think critically and logically to make the relationships between evidence and explanations, communicate results, and use mathematics in all aspects of scientific inquiry.
Locally, physical characteristics of rocks can be compared and correlated.