I figure you'll forgive me one more nerdy post.

Saturday morning we visited Joggins Fossil Cliffs, our final stop along the Bay of Fundy (now on the Nova Scotia side). Here a huge slab of sedimentary rock had subsided unevenly, leaving its layers slanted at an angle. That slant allows the 15 km of cliffs along the (horizontal) coastline to act as a timeline through about 15 million years' worth of (vertically deposited) sediment, all from approximately 300 million years ago. The area back then was mostly populated with plant life; giant ferns and trees.

The cliffs feature amazingly preserved fossilized tree trunks. We took a 2 hr walk with a guide who was great at pointing out the really neat ones.

The tides from the Bay of Fundy are constantly eroding the cliffs, exposing new fossils every so often. This rock broke away from the cliff this summer, right along the impression from a prehistoric tree trunk.

The tree fossils formed in 3 main stages: In the first, sediment would start piling up around the tree; in the second, the soft innards of the now dead trunk and root would rot away and be replaced by more sediment, while the hard bark remained intact and formed an impression on the sediment around it; finally, millions of years of pressure compressed the sediment into rock and the bark into coal. You can see a bit of coal around the outer edge of the fossilized root above (top left corner).