Two layers of rock contain trilobites that have the same body morphology;however,one rock layer is a shale and the other is an ironstone.Can these two layers be used for correlation?
A)No,layers with the same lithology can only be used for correlation purposes.
B)No,the ironstone has been altered by oxidation and thus is older than the shale.
C)Yes,if the trilobites are the same,then the layers were formed at the same time.
D)Yes,the ironstone is the altered remains of the shale and thus the layers are the same.

Question

Quizplus · Accepted Answer

The presence of trilobites with the same body morphology in both layers indicates that they were most likely formed during the same geological time period. The fact that one is shale and the other is ironstone does not preclude the use of these layers for correlation. Lithology (rock type) can vary within a single time period, so it is not necessary for the layers to have the same lithology to be correlated. Option A is incorrect, as layers with different lithologies can also be used for correlation. Option B is incorrect, as ironstone formation does not necessarily indicate that the rock is older than the shale. Option D is incorrect, as ironstone is not the altered remains of shale.

Two Layers of Rock Contain Trilobites That Have the Same