In the late 1700s scientists proposed that the layers in the rocks of mountains and canyons represented a record of the passage of time, with the younger layers lying on top of the older layers. What could they determine about the fossils they were finding in the rocks based on this observation?

Question

anonymous · Answer

Fossils in upper layers were younger than fossils in lower layers.
		Fossils in upper layers were less weathered and more detailed than those in lower layers.
		The exact age of a fossil could be determined by counting the rock layers.
		The oldest fossils were the same as the ones found in younger rock layers.

blues · Answer

It tells you that the strata in rocks provides info on the *relative* ages of the rocks. That is, lower rock stratas are older than higher rocks stratas. The key is that any fossils in the lower rock stratas are also older than fossils in the upper rock stratas.

anonymous · Answer

so its its D?

blues · Answer

Well if rocks in the lower layers are older than rocks in the upper layers, and the fossils in the rocks are the same age as the rocks themselves...

anonymous · Answer

now im between C and D :/

blues · Answer

Rock strata give you the age of rocks, relative to other the rocks in the strata. They do not give you the exact or absolute age of either new rocks or older rocks - they just give you that some rocks are older or younger than others...

And if the rocks were formed at different times, and the fossils were formed at the same time as the rocks) it is plainly not D either...

anonymous · Answer

ooooh! A is the answer ! am i right?

blues · Answer

Yes, I think it is A too. Thanks for working through it.

anonymous · Answer

thank you for explaining it !