Courtesy Mark RyanIn the latter days of summer my wife and I took a drive up the Gunflint Trail and visited the Magnetic Rock Trail, a spur trail jutting off the Gunflint near Gunflint Lake. Our original plans of lounging about the North Shore of Lake Superior had been scuttled by a mix-up in our cabin reservations, so I saw it as an opportunity to check out first-hand some of the local geology. I had visited the MRT briefly once before and my reasons for wanting to make the 50-mile drive from Grand Marais to revisit the trail were three-fold: stromatolites, meteorite impact ejecta, and, of course, magnetic rocks
Well, as it turns out, I wasn’t very successful,
Courtesy Mark RyanReaders may recall the Ham Lake forest fires raged along the Gunflint Trail in the early summer of 2007, destroying several hundred acres of the surrounding forest along with resorts and private property. The fire, it was later determined, was started by a legal campfire in the vicinity of Ham Lake that had gotten out of hand and spread quickly through the region. It was the second forest fire to rage through the Magnetic Rock Trail (MRT) in the past two decades (there was also a controlled burn in 2002). The latest fire removed much of the pine canopy that covered the area, opening it to more sky and sunlight, and new vistas of the surrounding terrain.
Courtesy Mark Ryan
Courtesy Mark RyanBut as destructive as forest fires can be, they do have their upside. Forests are quick to revitalize after fires. New trees soon rise up from the ashes, and evidence of that in the MRT was apparent in the many jack pines (Pinus banksiana) we saw sprouting up everywhere. But trees aren’t the only affected flora. A lot of the groundcover gets incinerated as well, sometimes exposing patches of bedrock. In the case of the Magnetic Rock Trail, it meant new outcrops of the Gunflint Iron Formation were uncovered, revealing fresh unexplored exposures.
The Gunflint Iron Formation is a mass of iron ore taconite that spans from the Arrowhead region of Minnesota eastward into Ontario, Canada with the majority of the formation located on the Canadian side of the border. Most iron formations on Earth were formed around the same time, about 2 billion years ago during the Middle Pre-Cambrian (Early Proterozoic) times. A shallow sea (the Animikie) covered much of northern Minnesota and eastern Ontario at the time. The sea teemed with cyanobacteria in the form of stromatolites; thick microbial mats that helped oxygenate the Earth’s atmosphere and metabolize iron out of solution through photosynthesis. The iron-oxide sediments later became the iron ranges that span across northern Minnesota and Canada. Much of the rock along the Magnetic Rock Trail is composed of magnetite (Fe3 O4) inter-bedded with layers of chert or shale. Magnetite is the most magnetic of all the naturally occurring minerals, hence its name. The Gunflint Iron Formation is particularly resistant to erosion on the Minnesota side probably due to its nearness to the Duluth Complex intrusives. These influxes of magma moved into the area around 1.1 billion years ago, adding tremendous heat to the existing strata. The portion of the Gunflint Iron Formations (that located in Minnesota) closest to the heat source shows the most resistance to erosion.
Courtesy Jim Miller, MN Geological Survey (top) Mark Ryan (bottom)Preserved within some of the newly exposed outcrops along the MRT are fossil records of these stromatolites, representing some of the oldest fossils found in Minnesota. Gunflint stromatolites contain large numbers of fossils that can be seen under a scanning electron microscope. I had been told that you can walk off the main path and find some of these ancient fossils, so I searched off-trail for a while and found what I thought were stromatolites, and took photos of them.
But later when I consulted with geologist Mark Jirsa, he wasn’t so sure.
“You're looking at thin bedding in the iron formation that dips shallowly in comparison to the dip of the outcrop surface,” he wrote me. “The result is a swirly look, that looks deceptively like stromatolite mounds.”
Jirsa was in the field when I contacted him, and his Internet capability was limited, so when he tried to send me some photos of what the stromatolites actually looked like, they didn’t come through. However, his colleague, geologist Jim Miller (who also supplied welcomed assistance with this post) sent me a stromatolite photo he had taken at MRT.
Personally, I can’t tell the difference, but then I’m no geologist. so I have to bow to the professionals.
My second quest – to locate and photograph ejecta from the Sudbury Impact – wasn’t successful either. The aforementioned Mark Jirsa discovered this record of a 1.85 billion-year-old meteor impact in 2007. I wrote a previous post about it that same year so I won’t go into those details (you can read it here) but I will bring you up to speed on how he’s since interpreted the find.
Briefly, the Sudbury Impact Crater is located in Ontario, Canada, and was made by a meteorite about 10-miles in diameter that slammed into the Earth 1.85 million years ago. The 150-mile wide crater is the second largest known on the planet. The collision sent a tremendous firestorm of superheated material into the atmosphere, and some of it coalesced like hailstones and landed 480 miles away in northeastern Minnesota. This is what Jirsa discovered two years ago: a layer of ejecta mixed with torn up pieces (breccia ) of the Gunflint Formation, and all of it overlain by a younger layer of slate known as the Rove Formation. He published an article about it in Astronomy magazine, and there’s also a PDF file downloadable from Minnesota Geological Survey website (the link is located in the upper left of the MGS homepage).
What Jirsa found was quite remarkable: a layer of churned-up rocks laid down above the Gunflint Iron Formation. The odd jumble of rock included berry-shaped rocks known as accretionary lapilli, intermixed with the Gunflint Iron Formation rock. According to his interpretation, what is seen in the layer essentially shows the events of a single day in the geological record. And a nasty day it must have been.
Three minutes after the initial fireball impact at Sudbury, seismic waves from earthquakes measuring more than magnitude-10 on the Richter Scale reached the Animikie basin, ripping loose the iron formation off the seafloor crust, and redistributed it along a submarine slope. Within 10 minutes, a firestorm of molten material hailed down from the sky covering the region with from 3 to 10 feet of ejecta in the form of accretionary lapilli. Ultra-hurricane-force winds measuring up to 1400 mph(!) blasted over the shallow sea soon after, followed by the coup de grace – titanic tsunamis the likes of which have never been seen since which tossed everything into a stew of breccia (jumbled rock) and berry-shaped ejecta.
This day of horror took place sometime in the 48 million year interim that separates the Gunflint Iron Formation and the time the sediments of the Rove Formation were laid down above it. The entire concoction was later baked and metamorphosed by the intrusive magmas of the Duluth Complex.
How hard could it be to find evidence of a mess like this? Well, considering the MRT covers a large area, and since I had no information pinpointing any locations, it was like looking for a needle in a haystack – a very large haystack. In the end, I soon gave up because I really didn’t know what I was looking for and I realized how futile it probably would be. However, I’ve sure learned a whole lot about it now.
Courtesy Mark RyanInitially, I thought at least my third quest – finding magnetic rock – would be a complete success because just about every rock exposed along the MRT is highly magnetic (I had a magnet with me and I can attest to that fact – see photo). It made sense that the whole reason the trail is called the Magnetic Rock Trail is because of all the magnetic rocks found there. But I’ve since learned I was once again totally wrong. The trail is name after a single large magnetic rock that’s about 1.5 miles up the trail. This 30-foot monolith stands upright and obvious in the middle of the forest and its notoriety dates back to early native American times. It is a chunk of the Gunflint Iron Formation – and highly magnetic like the rest of the rock in the area – but is deemed an erratic moved into place from a short distance away by glaciers during the last Ice Age. Had I read any of the brochures I had collected on our trip sometime other than when I got home, I would have known this before I even got there. But as it was, we didn’t walk that far into the trail so we missed it completely. Oh, well.
Courtesy Mark RyanBut even though my three main objectives for visiting the MRT were pretty much complete washouts, there was one unexpected surprise that will probably draw us back to the region next year: blueberries.
Courtesy Mark RyanWild blueberries (Vaccinium angustifolium) were all over the place. The low-bush berries thrive in sandy, acid soils of forest clearings, and in rocky areas around pines forests – just the type of environments you find around the MRT. So, once I finished with my failed geological studies, I assisted my wife in picking as many wild blueberries as we needed. We kept them in our cooler for the ride home, and as Mrs. R is prone to do, she jumbled all the berries together into a viscous concoction, all within a flakey crust that was heated over time at a very high-temperature.
The result looked something like the Sudbury Impact ejecta layer found near the Magnetic Rock Trail, but it was much more delicious, and a great way to end the summer.
This year has been designated The Year of Science 2009, and the theme for the month of August is weather and climate. What better way to celebrate than to dust off one of my old videos and show it again on the Science Buzz blog. I shot the video over Lake Harriet when one of those typical thunderstorms rolled through Minneapolis a few summers ago. We're obsessed with weather here in Minnesota, and I'm particularly crazy for thunderstorms!
If you want more information about this month's theme you can find it at the Year of Science website.
Courtesy teapicPack your bags, Buzzketeers, because you don’t want to be the last person to make it to the world’s newest, creepiest continent. (Don’t worry, Australia, I’m not talking about you.)
Trashlantis! The new frontier! The Texas-sized plastic layer floating in the middle of the Pacific Ocean! Why would you not want to go there? The answer, of course, is that you wouldn’t not want to go there… ever!
Yet another scientific expedition is on its way to the fabled plastic continent. But while the last group of researchers mentioned on Buzz was at least partially motivated by the potential to turn Trashlantis back into some more useful hydrocarbons, it looks like these folks are more interested in seeing how the plastic is affecting sea life.
The Yahoo article linked to above sums up the expedition with:
”The expedition will study how much debris -- mostly tiny plastic fragments -- is collecting in an expanse of sea known as the North Pacific Ocean Gyre, how that material is distributed and how it affects marine life.”
I’m guessing what they’re getting at has to do with how plastic affects very very small organisms as it photodegrades. We understand how chunks of plastic in the ocean are no good for larger animals—marine life can choke on them, or fill their stomachs with trash—but the problem goes further than that. See, eventually those larger pieces of plastic start to photodegrade. (That means they get broken down by the energy in sunlight.) But photodegredation doesn’t seem to actually get rid of the plastic, it just breaks it into increasingly smaller pieces. When a plastic bag turns into a million little tiny chunks, it no longer poses a risk for, say, a sea gull choking on it. But smaller organisms are still likely to gobble some up, and if they can eat anything bigger than they can poop (it happens), they’re in a lot of trouble. And when small organisms die off, so do the slightly larger creatures that eat them, and the larger creatures that eat them, and so on. (You remember this from grade school.) So how will Trashlantis fit into this plasticky food-path?
And then there’s the huge real estate potential for Trashlantis. So get there now.
Courtesy KinnicChickOk. The startup of the Large Hadron Collider, the biggest, fanciest machine ever built, the doomsday atom-smasher, the revealer, the secret-finder, the lens of God* has once again been delayed, this time from October to November.
The machine that will make sense of it all, or start an apocalyptic chain reaction in the matter of our planet, has a couple little helium leaks that need to be repaired. If I were the director of the project, I’d just get a couple interns to stick their fingers in the holes (or have them put their mouths over the leaks for hilarious squeaky interns), but the folks in Switzerland aren’t screwing around.
“We’re going to get it right this time! November? Maybe! Maybe later! Don’t push us, okay? Do you want us to blow up the world? We will, so help me, we will! I am so frustrated!” stated one scientist I just imagined.
So you’ve got one extra month, at least. What are you going to do with it? The possibilities are practically endless. Here are some suggestions:
BTW, if you’ve already forgotten what the LHC is, and what it’s supposed to do, check out some of our older posts on it here.
*When I enter Thunderdome, I want all of this to be my introduction. Especially “The Doomsday Atom-Smasher” part†
†Holla back, Mad Max enthusiasts! Who rules Bartertown?
Courtesy Mark RyanRecently my wife and I took a day trip to the North Shore of Lake Superior to hike around, take pictures, and see some great geology. Scenic Highway 61 follows the lakeshore all the way into Canada, and along the way several state parks present some of the most stunning scenery and spectacular geology you’ll find in Minnesota.
In Duluth, a brisk wind made the lake a bit choppy down around the harbor entrance and small white caps rolled into the beaches of Park Point, but along the North Shore the wind subsided and the lake was placid and sparkling. It was a beautiful day, with bright sun and cool to moderate temperature, and air that was an especially clear. Across the lake, Wisconsin stood out in bold silhouette on the south shore.
Our first stop was Gooseberry Falls State Park just north of Two Harbors. One of nine state parks along the North Shore, Gooseberry is located just beyond the tunnels that cut through massive diabase ridges known as Silver Cliff and Lafayette Bluff. Diabase is an intermediate volcanic rock that due to its cooling rate, contains coarser-grained crystals than faster cooling basalt and smaller crystals than slower cooling gabbro.
Courtesy Mark RyanGooseberry offers easy parking and paved walking trails to view the three main waterfalls (Upper, Middle, and Lower). Despite the brisk afternoon air temperature, the waters of the Gooseberry River were warm and kids were having no problem swimming or standing under the falls. Three tiers of lava flows give the falls their structure partially due to the columnar jointing that took place when the basalt was first cooling from the outside in and shrinking into hexagonal joint structures in the process. The columnar jointing is easily viewed atop the Middle Falls. Down river the upper most flow makes up the ledges along the lakeshore.
You might wonder why so much volcanic rock is found along the North Shore. The reason’s because 1.1 billion years ago, the North America continent began to split apart in what’s called the Midcontinent Rift System. From Michigan up through the middle of Lake Superior, down Minnesota and into Kansas, the continent began to separate, releasing massive amounts of flood basalts and explosive rhyolites across the region during several eruptions. The level of volcanism was incredible, lasting for several million years. In some places along the North Shore it’s estimated that the lava flows are piled up 18 miles thick! But for reasons unknown (and lucky for us) the continental division was aborted, leaving us with interesting geology, several rugged parks, and gorgeous scenery.
Courtesy Mark RyanOur next stop was Palisade Head located within the boundaries of Tettegouche State Park. A steep road takes you to the parking area at the top of the promenade. There are a couple low walled overlooks built from local rock for viewing but you can also hike around if you want. The view is fantastic. Shovel Point, located in the park proper, can be seen sticking out over the lake to the northeast with the Sawtooth Mountains in the background. Both Palisade Head and Shovel Point were created from the same lava eruption, but one quite different from those that created Gooseberry. Whereas flood basalts created Gooseberry, an explosion of rhyolite formed Palisade Head and Shovel Point. Rhyolite is chemically similar to granite but rather than being an intrusive rock (one that cooled slowly underground) as granite is, rhyolite is extrusive, meaning it cooled relatively quickly on the surface. Evidence shows the lava flow that created both Shovel Point and Palisade Head was one of great explosive energy. As the mass of magma neared the surface pressure dropped and volatiles in its mixture (such as water) expanded its volume and punched it through a vent in the Earth’s crust in a hail of molten ash and rock. The molten material settled into a pancake-shaped mass that eventually cooled into a highly erosion-resistant rock. But the relatively rapid cooling from the outside in once again caused columnar jointing, like that seen in Gooseberry.
Courtesy Mark RyanThe jointing and high cliffs that reach up 300 feet above the lake make Palisade Head a favorite site for rock-climbing. A group was doing just that when we were there.
Courtesy Mark RyanOur final stop was Sugarloaf Cove just outside the town of Schroeder. This preserve is a recent addition to the scenic North Shore. From 1943 to 1971, the cove was used by a paper company to ship rafts of pulpwood across the lake to paper mills in Ashland, Wisconsin. But today practically all traces of the business have disappeared and the 34-acre site is being preserved by the State of Minnesota and the Sugarloaf Interpretive Center Association for educational purposes. Seven acres have been designated as a State Scientific and Natural Area. A fenced area protects a native plant restoration project where volunteers planted over 12,000 native trees, plants, flowers, and grasses.
Courtesy Mark RyanThere’s a one-mile trail that takes you through a pine plantation and alder thicket and down along the lake’s rocky shoreline and to the cove. Across the cove is Sugarloaf Point, which used to be an island but is now connected to the mainland by a tombolo, a shoreline feature formed from wave action depositing sediment over a shallow area of the lakeshore. As you walk the beach toward Sugarloaf Point you’ll notice the beach deposits become increasingly larger in size, going from fine sand to large cobbles, and even an occasional boulder. Glaciers carried most of these stones from areas north and northeast, smoothing their edges in transport and depositing them here as glacial till. Lake Superior’s wave action continued rounding the stones, at the same time sorting out the sand, gravel, and cobbles by size.
Courtesy Mark RyanOn the south side of Sugarloaf Point several lava flows can be seen piled one atop the other. When lava poured out on the surface a billion years ago, gases within the molten mixture formed bubbles that rose to the top of the flow much like bubbles forming on top of a pancake. As the molten material cooled into rock, these gas pockets – known as vesicles – became trapped. Additional pulses of lava soon covered the old flow and eventually everything became buried under younger sediment. At some point, hot ground water percolated through the buried masses of basalt and deposited different minerals in the vesicles in the process. These mineral deposits are known as amygdules and often appear as lighter crystals (zeolites) or agates inside the basalt layers. So when you see these lighter crystals in a rock sequence at Sugarloaf you know you’re looking at the top of a lava flow.
Courtesy Mark RyanVegetation on the point is very fragile, and visitors are requested not to walk out on it. At the far end of the point several lichens are working hard breaking down the basalt, along with the constant wave action of Lake Superior.
After this trip I’m anxious to go back and visit the other state parks along the North Shore. The area has so much to offer in terms of nature and geology. You can learn more by checking out some of the links below. There’s also a great book by geologist John Green titled Geology on Display that’s all about the geology of the state parks along the North Shore. If you get a chance this summer to visit these or any of the other beauty spots along Superior’s North Shore, take it - you won’t be disappointed.
Jay Cooke State Park
Split Rock Lighthouse State Park
Crosby Manitou State Park
Temperance River State Park
Cascade State Park
Judge C. R. Magney State Park
Grand Portage State Park
More about the geological history of northeastern Minnesota
Restoration of Native Plant Communities at Sugarloaf Cove
Courtesy Incredible India
Get ready, because one of Newton’s laws is about to be tested. A little thing called gravity is going into question during the total solar eclipse on July 22nd.
I’m sure most of you have heard of or know what a solar eclipse is. If not, here’s a refresher: “A solar eclipse occurs when the Moon lies between the Sun and Earth, casting its shadow on our planet. Depending on the location of the observer on the Earth’s surface, the observer may see a total solar eclipse, a partial solar eclipse or none at all. If the observer is lucky enough to be located in a position where the moon’s umbra contacts the Earth they will witness a total solar eclipse of the sun.”
Unfortunately for those of us in St. Paul, the only way for us to see the total solar eclipse would be to buy a one-way ticket to the eastern hemisphere. The path of the eclipse will start in eastern India and end about 2,000 miles south of Hawaii. During which it will be visible for nearly 6 minutes in China, and that’s where Newton steps in (not literally of course).
Researchers at the Chinese Academy of Sciences are about to test the controversial theory that gravity drops slightly during a total eclipse. Originally observed in 1954, the French physicist Maurice Allais noticed erratic behavior in a swinging pendulum when the eclipse passed over Paris. The shift in direction of the pendulum’s swing suggests a sudden change in gravitational pull. Though tests have occurred since, nothing has been conclusive.
The best chance to prove the gravity anomaly is this Wednesday during the longest eclipse duration of the 21st Century. This is why Chinese geophysicists are preparing six different sites with an array of highly sensitive instruments to take gravitational readings during the total eclipse. The head geophysicist Tang Keyun states, "If our equipment operates correctly, I believe we have a chance to say the anomaly is true beyond all doubt."
NASA's Earth Observatory is celebrating its 10th anniversary this year and in that time is has given scientist and the general pubic a new view on the earth and how it is changing. The Earth Observatory site has satellite images of events on the earth ranging from storms and climate change to the growth of cities. The images are not only interesting to look at but they have helped scientist research the changing of seasons, snow caps, and cloud patterns in a whole new way. With growing popularity the images are also being sought out by other agencies, for example when the coast of Louisiana was hit by a hurricane the images were used to get a clearer picture of the flooding in the cities. Check out their archives, you will see awesome pictures and learn something new about the planet we live on.
Courtesy Pabo76What say we take a breather from all the bleak and uncertain flu news and turn our collective attention to the possibility of a tsunami washing away the East Coast of the USA? Fortunately no such threat is on the horizon at the present moment but scientists have found evidence they say indicates a large tsunami hit areas of New York and New Jersey some 2300 years ago.
The evidence includes large gravel, wood deposits, and marine fossils found in core samples across the region dating to 300BC, and suggests some sort of violent event took place in the region. The size and condition of some of the deposits point to strong reworking of material rather than just a single violent storm. The wave is estimated to have been 9 to 12 feet in height with the velocity of the water estimated at about a meter per second. If a similar tsunami hit Manhattan today no doubt there’d be big trouble.
But Atlantic tsunamis are rare events. Unlike the Pacific and Indian oceans where tectonic plates are colliding and earthquakes are more common, the plates along the Atlantic ridge are spreading apart. That’s not to say an Atlantic tsunami isn’t possible today. In 1929, a tsunami swept into the coast of Newfoundland killing more than two dozen people. The cause was a massive underwater landslide triggered by a 7.2 magnitude earthquake on the Grand Banks.
But neither an earthquake nor a submarine slump may have been involved in the 300BC tsunami. Recent research indicates an asteroid impact somewhere off the Atlantic coast dating to about the same time. Ejecta found in the local sediments such as spherules, shocked quartz, and nanodiamonds could only have been created under extreme temperatures and pressures produced by an extraterrestrial. No crater has been located as of yet but the scientists continue searching.
Remember on TV's Star Trek how Captain Kirk's impossible requests were always put off by his chief engineer, Montgomery Scott? Scotty favorite excuse for avoiding work was to claim it just wasn't physically possible. This from the guy whose engineering skills could propel a starship across the universe at Warp Factor 10 using a couple lousy dilithium crystals. Or maybe he just had better things to do. Whatever the case, it looks now like Scotty's favorite work shirk excuse may no longer be valid. At least not in the world of nanoclusters.
While exploring strange new worlds using computer modeling and nanoclusters made up of several hundred atoms, researchers in Japan have observed tiny clumps of atoms that seem to break the second law of thermodynamics. Don’t think crime is rampant in the nano-world. Most of the atoms observed were law-abiding. When the nanoclusters collided at just under 12 miles per hour, most of them either clumped together like sticky mud, or bounced off each other and went on their way at a slower speed.
But a small percentage of nanoclusters (less than 5%) bounced away at an increased speed, acting as if they picked up an extra boost of energy.
It’d be like dropping a golf ball on the sidewalk and instead of it gradually losing energy (as absorbed heat) and eventually coming to a dead stop, as expected, it just went higher and higher with each successive bounce until it finally bounced into orbit. That just doesn’t make sense. Or as Scotty’s cohort Mr. Spock would say: “Logic and practical information do not seem to apply here.”
According to the researchers, Hisao Hayakawa, of Kyoto University, and Hiroto Kuninaka, of Chuo University in Tokyo, the so-called super rebound resulted from random internal changes of motion in the nanocluster’s atoms, some of which can give the collision an extra boost, like jumping on a trampoline.
Sounds like we got ourselves the makings for some sort of perpetual motion machine here. Well, not quite. Apparently, this scofflaw behavior can only take place in very tiny systems. When the researchers increased the cluster’s atoms from hundreds to thousands, the behavior disappeared completely.
Besides that, the system as a whole still followed the letter of the law. The second law deals statistically with millions of atoms, so even though some nanoclusters picked up extra energy, the clusters overall dispersed energy and headed towards increased entropy just as the law prescribes, and in the end all is well with the universe.
So far the phenomenon has only been seen in computer simulations. But Hayakawa expects it won’t be long before it’s observed in real world experiments. The research findings appeared in the March issue of Physical Review E.