Let's Discuss Geology!!

[Hellbent]

So I'm something of a Geo minor and since several people on here have shown proclivity to the sciences, I thought maybe we could get some good discussions going on some Geologic topics, specifically those relating to Earth History and paleontology as those are areas of study most interesting to me.

Little quiz to start things off. What formed the image below? When did it happen? What is its significance, if any, to earth history?

HINT: take a look at the url.

BONUS: How, if in any way, does it relate to DooM?



You know I have to say, compared to other 'special interest' forums, Doomers are quite smart!!

[GreyGhost]

Hazarding a wild guess I'd say it's the remains of an impact crater, which - depending on the magnitude of the impact - could have resulted in a global mass extinction event. Can't think of any relationship to Doom apart from crispy critters.

[Sharessa]

It's either an impact crater or a really weird caldera. Relation to Doom...is it near Mt. Erebus?

[Hellbent]

You guys are right that it's an impact crater. I'll wait for more replies before saying anything more. But I'm sure you can put on your detective hats to figure the answers out. ;p One interesting thing about the feature is that it's actually now classified as a lake because it is an enclosed body of water. Seems like a moat would be a more appropriate labeling tho.

[Remilia Scarlet]

It's an impact crator called Manicouagan Reservoir, in Quebec. The highest peak is Mount Babel (E2M8?).

[Hellbent]

DJ_Haruko said:

It's an impact crator called Manicouagan Reservoir, in Quebec. The highest peak is Mount Babel (E2M8?).

Yessir. But the question is.. why didn't it cause a mass extinction? The Chicxulub crater formed at the time the Dinosaurs were wiped out did. The craters are of similar size as well. But there is no indication of a mass extinction or a drop in fauna diversity at the time of the impact 212Ma.

[Espi]

They're both huge, sure, but not similar in size. Chicxulub is much larger.

[Chilly Willy]

Actually, id had a marketing company dig that out to promote Quake when it was first released. ;) :)

[Hellbent]

Espi said:

They're both huge, sure, but not similar in size. Chicxulub is much larger.

The Chicxulub crater is more than 180 kilometers (110 mi) in diameter, making the feature one of the largest confirmed impact structures in the world; the impacting bolide that formed the crater was at least 10 km (6 mi) in diameter.

Manicouagan Reservoir lies within the remnant of an ancient eroded impact crater (astrobleme). The crater was formed following the impact of a 5 kilometres (3 miles) diameter asteroid which excavated a crater originally about 100 km (62 mi) wide although erosion and deposition of sediments have since reduced the visible diameter to about 72 km (45 mi). It is the fifth largest impact crater known on earth (Wikipedia)

You're right, it's much larger. I confused 100 kilometers with 110 miles.... It's interesting that the relationship between asteroid size and crater size is quite similar between the two impact sites.

[GreyGhost]

Hellbent said:

Yessir. But the question is.. why didn't it cause a mass extinction? The Chicxulub crater formed at the time the Dinosaurs were wiped out did.

A recent research paper suggests that impact events on their own mightn't be sufficient to cause mass extinctions. There are indications that dinosaur populations were in decline before the Chicxulub impact, possibly as a result of the Deccan Traps eruptions which were ongoing for millions of years before and after.

[Hellbent]

GreyGhost said:

A recent research paper suggests that impact events on their own mightn't be sufficient to cause mass extinctions. There are indications that dinosaur populations were in decline before the Chicxulub impact, possibly as a result of the Deccan Traps eruptions which were ongoing for millions of years before and after.[/b]

from the paper:
Fossils were analyzed on either side of the iridium layer and the researchers found that of 52 species counted below the iridium layer (meaning before the impact), the same 52 species were found above it, meaning the asteroid hadn’t caused any extinction. But at the top of the 30 feet of sandstone overlaying the iridium claystone things were different.

"The mass extinction level can be seen above this interval," Keller says. "Not a single species went extinct as a result of the Chicxulub impact."'

My Geo professor didn't think the Deccan Traps were large enough to have had enough impact to cause an extinction event on the magnitude of the K/P, but I tend to agree with the idea that they correspond with the steady decline of dinosaurs. His argument was that they simply weren't large enough. I'm also skeptical that they can age things so precisely. You're talking about sediments deposited 65 million years ago. How can you be so sure it took 300,000 years to deposit those layers? Most geologic aging of millions of years old events carry with them a +- error margin of a million years or so.

from the research paper "Dinosaur-killing asteroid may be off the hook":
[b]Recent dinosaur fossils found in the San Juan Basin in northwestern New Mexico are suspected to come from a stratum that post-dates the Cretaceous extinction. More research needs to be done on the find, but even this wouldn’t be unexpected. Even after the host declares the party’s over, there are always some stragglers who just don’t want to leave.

But one needs to be careful of the Lazarus Effect where fossils known to be extinct get reworked into newer rocks.

from "The Lazarus Dinosaurs of James Fassett":
While I am no expert on the subject and could very well have missed some finds, most of the alleged fossils are bone fragments and teeth (teeth being especially durable), fossils that easily could be exhumed and reburied (=”reworked.” “Transport” means travelling some distance away from the original site and only sometimes is such material reworked) in Paleocene deposits (thus being buried with Paleocene-age pollen). To the best of my understanding, there are no Paleocene dinosaur tracks, no articulated Paleocene dinosaur skeletons (which means there was little disturbance/no reworking), no Paleocene dinosaur skulls, no Paleocene dinosaur nests, or anything that would absolutely rule out reworking in some form or another. One of the prominent locales at which this reworking occurs is the Hell Creek Formation of Montana, and the subject has already been dealt with at length in the literature. From the 1990 Lofgren, et al. paper “Reworking of Cretaceous dinosaurs into Paleocene channel, deposits, upper Hell Creek Formation, Montana“;

And the salient quote from the just referenced paper:
Dinosaur teeth from Paleocene channel fills have been interpreted as indicating dinosaur survival into the Paleocene. However, enormous potential for reworking exists because these records are restricted to large channel fills that are deeply incised into Cretaceous strata. Identification of reworked fossils is usually equivocal. This problem is illustrated by the Black Spring Coulee channel fill, a dinosaur-bearing Paleocene deposit in the upper Hell Creek Formation of eastern Montana. In this example, the reworked nature of well-preserved dinosaur bones is apparent only after detailed sedimentological and palynological analysis.

Because of the potential for reworking, dinosaur remains derived from Paleocene fluvial deposits should not be assigned a Paleocene age unless they (1) are found in floodplain deposits, (2) are articulated, (3) are in channels that do not incise Cretaceous strata, or (4) are demonstrably reworked from Paleocene deposits. To date, reports of “Paleocene” dinosaurs do not fulfill any of these criteria. Thus, the proposal that dinosaurs persisted into the Paleocene remains unsubstantiated.

I think another problem with Keller's hypothesis is that if the dinosaurs didn't go extinct by an instantaneous event, then why does the fossil record show an abrupt end? If they were steadily on the decline, wouldn't they steadily decline until extinct and not steadily decline and then abruptly be extinct?

[Sharessa]

I remember some argument against dinosaurs and the like surviving into the modern age and it said that they MAY have lasted in small pockets here and there, but they surely would have evolved into something different in that time.

Oddly enough, I had a dream last night where someone claimed pterodactyls were still around as late as 1000 years ago or something.

I have a lot of interest in cryptozoology, so reports of relict populations always interest me. For instance, there are reports that the giant unicorn survived into historical times. Also, the occasional reports of living mammoths out in remote areas of the arctic circle.

[Hellbent]

Danarchy said:

I remember some argument against dinosaurs and the like surviving into the modern age and it said that they MAY have lasted in small pockets here and there, but they surely would have evolved into something different in that time.

Oddly enough, I had a dream last night where someone claimed pterodactyls were still around as late as 1000 years ago or something.

I have a lot of interest in cryptozoology, so reports of relict populations always interest me. For instance, there are reports that the giant unicorn survived into historical times. Also, the occasional reports of living mammoths out in remote areas of the arctic circle.

Unicorn legend comes from a rhinocerous? I thought it came from a horse with a horn. :p

My dad believes that dragons were around 1,000 years ago. I'm not sure that the fossil record quite backs that one up tho. Do you believe in big foot? And Lochness?

[Necros20]

There always have been urban legends of prehistoric animals still existing.

[Sharessa]

Hellbent said:

My dad believes that dragons were around 1,000 years ago. I'm not sure that the fossil record quite backs that one up tho. Do you believe in big foot? And Lochness?

Bigfoot, yes. Nessie, no.

[Hellbent]

Danarchy said:

Bigfoot, yes. Nessie, no.

i wonder what keeps the populations down. Big Foot seems like it'd be an apex predator like humans. Humans obviously aren't a threat to them.

[Butts]

There is a record of coal miners around 200 years ago or so who found a preserved pterodactyl encased in some sort of mineral. I read it in some book about random logic-defying events that sound really untrue, but supposedly are.

[Hellbent]

Butts said:

There is a record of coal miners around 200 years ago or so who found a preserved pterodactyl encased in some sort of mineral. I read it in some book about random logic-defying events that sound really untrue, but supposedly are.

Google Cretaceous Lagerstatten or Burgess Shale... pretty cool stuff!!

[Sharessa]

Hellbent said:

i wonder what keeps the populations down. Big Foot seems like it'd be an apex predator like humans. Humans obviously aren't a threat to them.

They definitely are an apex predator. I don't think it has much to do with them being particularly scarce (though they aren't too, at least in most of the country) so much as them avoiding humans.

First of all, they tend to live in places very remote. Secondly, they're very smart. Smarter than any other critter out there aside from humans. Third, they're far more adept in the forest than humans. They seem to be able to stalk noiselessly through the forest and blend in well with the shadows. Many witnesses have claimed to suddenly notice one standing not too far away from them and speculating that it had been standing there for quite a while...or seeing an odd stump in the forest, turning away for a minute then noticing it's gone. Fourth, I think sightings of them are rather under-reported. Many witnesses who report their encounters are reporting things that happened years or decades ago, and were afraid to say anything out of fear of ridicule or fear that they were losing their minds. There's also the factor of witnesses in certain rural areas not reporting them because they're just too used to them.

That being said, the number of sightings does seem to be on the rise. I think this can be accounted for due to several factors. First, environmental concerns over the last few decades have actually helped the wildlife in North America considerably. Endangered species have bounced back, other species have thrived more, and as a result sasquatch populations are likely on the rise. Secondly, there is a shift in human population. More development is going on in wilderness areas bringing humans into the territories of wildlife (leading to things such as cougar attacks in people's backyards going up in the West Coast). At the same time, many farms and rock quarries have been abandoned in the last half-century or so, leading to the factors of my first point. Third, as more scientific information about sasquatches pours in, more people are getting interested and actively searching for them. The internet is also getting people together to pool their resources. It's also getting a lot of people to come forth with their sightings.

Anyway, yeah. It's a pretty fascinating subject, and if you're interested in theoretical discussions of this nature, I'd suggest reading the forums here.

[destx]

I heard sasquatch bitches are total freaks in the sack.

[Hellbent]

destx said:

I heard sasquatch bitches are total freaks in the sack.

Yes, but are human and Sasquatch offspring fertile?

[Fletcher`]

Hellbent said:

Yes, but are human and Sasquatch offspring fertile?

I warned your mom of the dangers, but damn man.

[myk]

Hellbent said:
But the question is.. why didn't it cause a mass extinction? The Chicxulub crater formed at the time the Dinosaurs were wiped out did. The craters are of similar size as well. But there is no indication of a mass extinction or a drop in fauna diversity at the time of the impact 212Ma.

Aside from the size difference you guys addressed above, perhaps you don't always get the same effects from large impacts, depending on the current climate conditions. If a meteor strike were to have enhanced a prolonged dry period, maybe partly caused by huge populations of dinosaurs, it might have devastated plant life the dinosaurs depended on, producing widespread death by starvation, thirst and disease.

Danarchy said:
I remember some argument against dinosaurs and the like surviving into the modern age and it said that they MAY have lasted in small pockets here and there, but they surely would have evolved into something different in that time.

[Technician]

Danarchy said:

I remember some argument against dinosaurs and the like surviving into the modern age and it said that they MAY have lasted in small pockets here and there, but they surely would have evolved into something different in that time.

[GreyGhost]

Danarchy said:

I remember some argument against dinosaurs and the like surviving into the modern age and it said that they MAY have lasted in small pockets here and there, but they surely would have evolved into something different in that time.

[myk]

Technician said:
[Synapsid pics]

These never were dinosaurs.