sedimentary, wisconsin

Can you spot the unconformity?

This photo displays a pretty spectacular unconformity—an erosional/non-depositional surface where rock units deposited during different intervals of time appear to be continuous.

In the bottom half of the image, you can see Paleoproterozoic pink quartzite ~1.7 Ga in age, while in the top half of the image—directly overlying the quartzite—is Cambrian sandstone conglomerate ~540 Ma in age.

That means that there’s a missing gap of over one billion years between the time when these two rock units were deposited!

Location: Devil’s Lake State Park // Baraboo, Wisconsin

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