Relative dating geology examples online dating strictly for ireland

The Proterozoic rocks of the Grand Canyon Group have been tilted and then eroded to a flat surface prior to deposition of the younger Paleozoic rocks.

The difference in time between the youngest of the Proterozoic rocks and the oldest of the Paleozoic rocks is close to 300 million years.

Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence.

Although with clever detective work many complex time sequences or relative ages can be deduced, the ability to show that objects at two separated sites were formed at the same time requires additional information.

The simplest and most intuitive way of dating geological features is to look at the relationships between them.

There are a few simple rules for doing this, some of which we’ve already looked at in Chapter 6.

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The lava flow took place some time after the diorite cooled, was uplifted, and then eroded.

(Hammerhead for scale) [SE] Figure 8.6b Rip-up clasts of shale embedded in Gabriola Formation sandstone, Gabriola Island, B. The pieces of shale were eroded as the sandstone was deposited, so the shale is older than the sandstone.

For example, a xenolith in an igneous rock or a clast in sedimentary rock must be older than the rock that includes it (Figure 8.6).

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