Relative dating rock layers worksheet answers

Relative dating rock layers worksheet answers

All of the fossils represented wouldThe following is aThe brachiopod crinoid

By correlating fossils from various parts of the world, scientists are able to give relative ages to particular strata. The cards in Set B represent rock layers containing various fossils. The brachiopod, crinoid, eurypterid, foraminifera, gastropod, horn coral, pelecypod, and trilobite could probably not be used as index fossils since they overlap more than one stratum.

It may be useful to share with students after they have completed Set B and answered the Interpretation Questions. Find a rock layer that has at least one of the fossils you found in the oldest rock layer.

Marine sedimentary rocks such as limestone, shale, and sandstone might contain fossils similar to those depicted in this activity. This also means that fossils found in the lowest levels in a sequence of layered rocks represent the oldest record of life there. Scientific measurements such as radiometric dating use the natural radioactivity of certain elements found in rocks to help determine their age. The nonsense syllables or letters sometimes overlap other cards and are being used to introduce the students to the concept of sequencing. By matching partial sequences, the truly oldest layers with fossils can be worked out.

It is recommended that students complete Procedure Set A and answer the associated Interpretation Questions correctly before proceeding to Set B. Return to top To enhance this activity, have students match the fossil sketches to real fossils.

Sequence the remaining cards by using the same process. This is called relative dating. For example, most limestones represent marine environments, whereas, sandstones with ripple marks might indicate a shoreline habitat or a riverbed. Locally, physical characteristics of rocks can be compared and correlated. Each card represents a particular rock layer with a collection of fossils that are found in that particular rock stratum.

The following question may help clarify this point. On a larger scale, even between continents, fossil evidence can help in correlating rock layers.

This will enable your teacher to quickly check whether you have the correct sequence.

The cards in Set B representBy correlating fossils from

If certain fossils are typically found only in a particular rock unit and are found in many places worldwide, they may be useful as index or guide fossils in determining the age of undated strata. The cards should be duplicated, laminated, and cut into sets and randomly mixed when given to the students. Scientists also use direct evidence from observations of the rock layers themselves to help determine the relative age of rock layers. Keep in mind that extinction is forever.

Specific rock formations are indicative of

Specific rock formations are indicative of a particular type of environment existing when the rock was being formed. The sequence must be exactly in the order as written.

All of the fossils represented would be found in sedimentary rocks of marine origin. The following is a list of fossils in the John Hanley Fossil Teaching Set that may be useful in this activity. The graptolite, placoderm, ammonite, ichthyosaur, and shark's tooth could possibly be used as index fossils since they are found in only one layer. Stratigraphic Section for Set B. This would also mean that fossils found in the deepest layer of rocks in an area would represent the oldest forms of life in that particular rock formation.

The sequence must