OCT 24: SEASON 1, episode 2: let's explore the dundee formation (part 2)
Mid-autumn is, for me, the ideal time for walking in the woods and looking for fossils: the temperature is neither too hot nor too cold; the underbrush that smothered the rock outcrops has thinned; no being attacked by swarms of springtime blackflies or mosquitoes, and no angry pladges of September wasps.
Today I ventured deeper into the Boler Mountain forest, encountering a white tail deer, a heron, and generally enjoying the boughs of now golden maples. And, of course, what the camera can never capture: the unique smell of an autumn forest that (at least for me) is its own form of exquisite nostalgia.
Today’s journey was perhaps as minimally eventful on the fossil front as last time. The Dundee Formation is not exactly the most thrilling when it comes to discovering fossil flora and fauna. This contrasts with the real excitement when you know the Middle to Late Devonian story - but more on that below. I did, however, encounter some rugose coral (the horn-shaped fellows), and another little brachiopod. It seems thus far that this area is almost entirely dominated by rather large anthozoan colonies. The amount of reef-building during this time must have been mind-bogglingly spectacular, especially for those who study coral reefs today.
Today I ventured deeper into the Boler Mountain forest, encountering a white tail deer, a heron, and generally enjoying the boughs of now golden maples. And, of course, what the camera can never capture: the unique smell of an autumn forest that (at least for me) is its own form of exquisite nostalgia.
Today’s journey was perhaps as minimally eventful on the fossil front as last time. The Dundee Formation is not exactly the most thrilling when it comes to discovering fossil flora and fauna. This contrasts with the real excitement when you know the Middle to Late Devonian story - but more on that below. I did, however, encounter some rugose coral (the horn-shaped fellows), and another little brachiopod. It seems thus far that this area is almost entirely dominated by rather large anthozoan colonies. The amount of reef-building during this time must have been mind-bogglingly spectacular, especially for those who study coral reefs today.
Following a shallow stream not too far from a cornfield
Just your run-of-the-mill calcified coral fragment (tabulate colonial). Much of the definition of the tabulae is obscured in this specimen. One of the features of the tabula corals is, unlike their rugosa cousins, they lack septae. And yet they still thrived just fine - for a time.
One of two specimens of solitary rugose coral. The significant weathering of the stone reveals its septa - how indecent! This one grew fairly straight (i.e., no bends) and so was likely orientated toward the sun with no difficulty, or water turbidity of the paleo-environment wasn't too high.
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Snapshot of your intrepid (and heavily bearded) amateur naturalist in his element.
Living the Devonian Dream
But let's provide a bit of context about the Dundee Formation and where it sits in the geochronology. 390-380 mya, much of the earth was covered in shallow, mild to sub-tropical seas. Some plants had already begun to populate the land, starting off the Devonian at about a foot tall to over a neck-craning 90 feet by the end of the Devonian. The seas were home to trilobites, corals, bivalves, cephalopods, and bony fish. If you look at the paleomap to the left, where I am hunting was once a fairly shallow reef-area near a landmass. Unless you were particularly tiny, swimming in the middle Devonian sea would have been somewhat pleasant, like taking a dip in the Bahamas. However, stick around for just a few million years and you get the double whammy of the Fellwasser and Hangenberg extinction events that bring the curtain down on the Devonian, and wipe out nearly 70% of all species. Waters became more turbid and anoxic after that, temperatures dropped, and dead things were not rotting very quickly (because of the anoxia). The end of the Devonian was a really bad time to be a trilobite or a tabula coral as both vanished as we step into the Carboniferous period. There is still a lot of debate and little fossil evidence as to what exactly precipitated this significant double extinction event. Some argue that it was an asteroid impact, while others increasing anoxia, and still others point the finger at rapid terrestrial plant development that might have led to increased global cooling since these plants functioned as a big carbon sink. A Simple and Pleasant Geology?
The most common stone in the Dundee Formation is limestone, coming in the exciting and festive colours of dull grey or sleepy beige. Atop these would sit a thin layer of anoxic shale, but London was not so lucky to have much record of the late Devonian extinction events. Instead, it is a coral-heavy fossil record of gentler, more tropical times. If this were a photo album, it would be a somewhat dull and repetitive one where the pictures are a bit hard to make out at times when the fossils and their rocky homes are grey on grey. If you are thinking "that reminds me of gravel," you are more right than you know given that this is precisely the stuff that gets made into gravel. We can, of course, get a bit of a perk of excitement if we take a drive up to Arkona or nearby Hungry Hollow that will be veritably stuffed with more coral, bryozoans, spirifers, etc., than you would ever possibly need (err... if you actually need them in the first place). I have heard even dim rumours that others have found specimens of phacops rana - it is a dream of mine to find one! The better we are at reading the rocks, the more interesting the stories they tell. Behind the gravelly-grey appearance are tales of occasionally violent seas, sudden deposit rushes, corals kinking in any which way to get at the light, and other heart-racing climate-based adventures of extreme weather events. Below is what London would have looked like 390 mya: 
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A tiny brachiopod (most likely schizophoria, and so a non-spiriferid brachiopod) next to a Canadian dime. Last week I neglected to bring any pocket change to show scale.
Apart from this, I did encounter some fairly interesting (to me) erosion patterns where water had cut deep fissures into the soil, and there is some bowl-effect in a few of the forested areas I tramped through.
Unless you are absolutely spellbound by endless outcrops of fossil corals, the Dundee Formation does not boast very much else with the exception of a few brachiopods - at least here in London.
In next week's episode, I will be taking my camera to campus to snap some pictures of fossils at Western (no, no, not the professors!). Stay tuned!
Apart from this, I did encounter some fairly interesting (to me) erosion patterns where water had cut deep fissures into the soil, and there is some bowl-effect in a few of the forested areas I tramped through.
Unless you are absolutely spellbound by endless outcrops of fossil corals, the Dundee Formation does not boast very much else with the exception of a few brachiopods - at least here in London.
In next week's episode, I will be taking my camera to campus to snap some pictures of fossils at Western (no, no, not the professors!). Stay tuned!
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Click on the button to view the next instalment where I creep the fossils at Western without arousing any suspicion. From landscaped slabs to an arts building, we'll encounter our usual Dundee regulars like corals and a few brachiopods, but also some imported limestone sporting nautiloids and a few other oddities.
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