Stories tagged geology

Literally dig deeper into the earth surface and discover what is lying right under your feet.

Minneapolis hosts 2011 GSA meeting: Six thousand geologists will descend upon Minnesota rocks this fall
Minneapolis hosts 2011 GSA meeting: Six thousand geologists will descend upon Minnesota rocks this fallCourtesy Mark Ryan
Next week the Geological Society of America is convening in Minneapolis, Minnesota for the GSA's 2011 Annual Meeting and Exposition. That means something like 6000 geologist, paleontologist, hydrologists, and other ologists from around the world will be in our area to share new ideas and hobnob with their fellow earth scientists. The four-day event, which is hosted by the Minnesota Geological Survey, runs from Sunday, October 9 through Wednesday, October 12 at the Minneapolis Convention Center, and will include special lectures, award ceremonies, poster sessions, an exhibit hall, and several hundred technical talks covering a full range of geology-related subjects. There will also be a silent auction, a photo exhibition, short courses (available to non-registrants), and a screening of the locally produced documentary, “Troubled Waters: A Mississippi River Story”. Field trips happening before, during, and after the official meeting dates will give visiting geologists an opportunity to take in some of the spectacular and diverse geology that Minnesota and the Upper Midwest has to offer, not to mention the fall colors. This year’s meeting is titled “Archean to Anthropocene: The Past is the Key to the Future”, and even if you can’t make it to Minneapolis, you can download a cool poster of the event here.

The GSA 2011 Annual Meeting and Exposition

Jun
05
2011

Scouring for fossils: (L to R) Ashley, John, and Chris search a hillside in Lilydale Regional Park for fossils.
Scouring for fossils: (L to R) Ashley, John, and Chris search a hillside in Lilydale Regional Park for fossils.Courtesy Mark Ryan
Summer seems to have finally arrived in Minnesota and that can mean only one thing: another season of fossil collecting is here. This year, due to near-record snowfall and spring floods, the St. Paul Parks department delayed issuing collecting permits for Lilydale Regional Park, one of the best fossil collecting sites in the Twin Cities. The park is located on the bluffs across the river from downtown St. Paul and is the former quarry and manufacturing site of the now defunct Twin Cities Brick Company. You can enter the park from above near Cherokee Park, or below from Harriet Island. Either way entails hiking a bit of a distance. There's a parking lot just off Water Street, and street and lot parking near Cherokee Park. Download map

Lilydale trail map: Located at the Bruce Vento Overlook near Cherokee Park.
Lilydale trail map: Located at the Bruce Vento Overlook near Cherokee Park.Courtesy Mark Ryan (photo)
The first permits for the "Brickyards" were issued last week, so a few of us from the Science Museum headed over to the park to spend some time searching for the fossilized remains of the marine life that once populated Minnesota during the Late Ordovician Period some 460 million years ago. Back then, much of the state was covered by a shallow, tropical sea, situated below the equator. Times certainly have changed.

The abundant fauna living in that prehistoric sea included reef-building bryozoans (the most commonly found fossil), brachiopods, lily-like crinoids, gastropods, horn coral, predatory cephalopods and everyone’s favorite, trilobites.

Decorah exposure at Lilydale quarries: John is dwarfed by the quarry wall at Lilydale Regional Park's West Clay Pit. The rocks exposed here are Late Ordovician in age (450-470 million years old), and contain fossils of marine life from a shallow sea environment that once covered southern Minnesota.
Decorah exposure at Lilydale quarries: John is dwarfed by the quarry wall at Lilydale Regional Park's West Clay Pit. The rocks exposed here are Late Ordovician in age (450-470 million years old), and contain fossils of marine life from a shallow sea environment that once covered southern Minnesota.Courtesy Mark Ryan
In general, there are three areas to collect fossils at Lilydale: the East, Middle, and West clay pits. Signs posted in several spots help direct you to collecting locations, but once you’re in the park you can find fossils just about anywhere.

The fossil quarries at Lilydale expose the Platteville and Decorah Formations that overlie the St. Peter Sandstone that forms the base of the bluffs found along the Mississippi. The Decorah shale here is about 90 feet thick and easily reconstitutes back into very sticky clay whenever rain or seeping ground water mix with it. But that usually won’t deter most hardened fossil hunters.

Receptaculites: John found the fossil just laying on the ground. It measures about 8 inches across.
Receptaculites: John found the fossil just laying on the ground. It measures about 8 inches across.Courtesy Mark Ryan
Multiple trilobites: Slab of Lilydale quarry shale loaded with the heads and other remains of trilobites and brachiopods. One head (cephalon) is enlarged for detail.
Multiple trilobites: Slab of Lilydale quarry shale loaded with the heads and other remains of trilobites and brachiopods. One head (cephalon) is enlarged for detail.Courtesy Mark Ryan
We had a pretty good day at Lilydale finding the usual crop of fossils, such as crinoid rings, brachiopod shells, and bryozoa branches. Chris pointed out some trilobite heads (cephalon) Ashley and I had overlooked in a couple small slabs of shale. John picked up a nice receptaculites specimen just setting on the ground. Later, while scanning the bluff, a piece of gray shale caught my eye. It was about six-inches in diameter and contained several brachiopods. But upon closer examination, I counted the remains of at least a dozen trilobites, mostly the heads of Eomonorachus intermedius.

Ordovician trilobite: Ashely displays John's fabulous find (Isotelus gigas?) from the Lilydale quarries.
Ordovician trilobite: Ashely displays John's fabulous find (Isotelus gigas?) from the Lilydale quarries.Courtesy Mark Ryan
But what my fossil possessed in quantity, John’s big find of the day overshadowed in quality. Picking through the clay piles that had slumped down from the top of the quarry since last fall, John plucked out a very well-preserved, rolled specimen of Isotelus gigas?, measuring about 1-1/2 to 2 inches across! It’s the largest trilobite I’ve witnessed come out of the Decorah. All the ones I’ve ever found were incomplete and maybe the size of a kernal of corn at best. But John’s fossil was a doozy. Unrolled it would measure a good 3 inches in length, if not more. I don’t like being outdone so I told John there’s no reason for him to hunt for fossils anymore - he’ll never find another specimen like that. But we both know he won’t be able to stop. That’s just the way fossil hunting is; there’s always the possibility of discovering a bigger and better find next time you go out.

Typical "shell hash" slab found at Lilydale
Typical "shell hash" slab found at LilydaleCourtesy Mark Ryan
Many of the Decorah fossils can be found weathering out on the surface, so you don’t need much in the way of tools. Some people like to bring a large bucket to serve as a stool while they’re in the quarries, and then for carrying out their fossils when leaving. I usually bring some plastic sandwich or freezer bags to hold smaller fossils. Some people use tissue paper or aluminum foil to wrap and protect their more precious finds. I do that sometimes. The clay pits also contain lenses of fossiliferous rock forming what’s known as "shell hash" – a chaotic jumble of fauna preserved in a matrix of limestone or shale. A rock hammer sometimes come in handy for breaking up large slabs into smaller, more portable ones, or for climbing the quarry banks.

School kids and buses swarm the Lilydale parking lot: Fossil-hunting in the quarries is a favorite extracurricular activity.
School kids and buses swarm the Lilydale parking lot: Fossil-hunting in the quarries is a favorite extracurricular activity.Courtesy Mark Ryan
If you go to hunting in the Lilydale quarries, you’ll want to bring along some water, and bug dope - mosquitoes weren’t yet a problem, but a couple wood ticks showed up. The driest parts of the quarry are of course in the sun, so if you're like me and burn easily, and don't want to spend most of your time searching in the muddier shade, it’s best to apply some sun-block lotion to your exposed skin. John also spotted several patches of poison ivy while we were scouring the West Clay Pit so you should keep that in mind, too. It’s an isolated area so be aware of your surroundings and it’s probably best to go with someone else. The quarry walls and hillsides can be unstable and treacherous. I've seen people take serious tumbles down the quarry face. Be aware, too, that there are no bathroom facilities at the quarries. There are lots of woods and bushes, though.

If you’re going to be there for a while you might consider bringing something to eat, too. Ashley brought a delicious seven-course gourmet meal for all of us to enjoy. Okay, that’s a slight exaggeration (it was only three courses), but after a few hours of intensive fossil hunting it sure tasted like one. Ashley has secured for herself a guaranteed slot in all future fossil hunting expeditions.

For information on acquiring a fossil-collecting permit for Lilydale, check out the Lilydale Regional Park permit page. Individuals and small groups of less than ten people pay $10 for a day permit. Larger groups pay more.

The Minnesota Geological Survey offers a nice information brochure about local geology, collecting, and identifying fossils at Lilydale and elsewhere around the Twin Cities. Download it here

Going home: The trail back to the Water Street parking lot
Going home: The trail back to the Water Street parking lotCourtesy Mark Ryan
I've listed a few more websites below to help get you started and make your fossil-collecting excursion to Lilydale more fun and informative. In general, hunting for fossils is kind of like fishing; you get to enjoy the outdoors, you get to occasionally make some nice catches (finds), and you get to bring them home and clean them. But best of all (besides not having to eat them), you get to boast to your friends about "netting" some sea creatures that are over 450 million years old. That, for me, is a fish story that's way more impressive than any fish tale concerning some old lunker that got away. So get out there and dig up the next great cephalopod fossil. You'll know exactly what I'm talking about.

LINKS

List of fossil sites and equipment
More trilobite info
More about horn coral
Collecting Fossils in Minnesota (previous Buzz post)
Minnesota DNR info page on fossils
Fossil Collecting in the Twin Cities
Lilydale trail map
Lilydale Regional Park
More about Lilydale Regional Park


James Hutton: Father of Modern Geology. Portrait by Sir Henry Raeburn.Courtesy Public domain (via Wikipedia)
James Hutton, born this day in 1726, was a Scottish farmer and doctor (although he never practiced medicine), and is often regarded as the "Father of Modern Geology". Through direct observations and studies of geological features in and around Great Britain, Hutton conceived the scientific ideas of uniformitarianism and deep time that directly challenged the popular biblical-based notion of the Earth being only 6000 years old. Hutton was a founding member of the Royal Society of Edinburough and his book Theory of the Earth set the basis for modern geological theory.

Hutton biography at Encyclopedia of Earth

This isn't today's Science Friday video, but it's a recent Science Friday video that I missed, OK? You'll like it, anyway. Science Friday
Science FridayCourtesy Science Friday
This time,
"In 1968, the New Jersey Senate decreed the town of Franklin a geological wonder: "The Fluorescent Mineral Capital of the World." Over 350 different minerals have been found in the area, ninety of which glow brilliantly under ultraviolet light. There are two mineral museums devoted to fluorescing rocks, the region's unusual geology and its zinc mining history."

This astounding video came to my attention via an email yesterday. It's yet another view of the awesome destructive power of the tsunami that arose from the Japan earthquake of March 11, 2011. The video was taken from a hillside in the resort town of Minami-Sanriku. It's amazing the kinds of events our modern technology allows us to witness.

James Hutton: Founder of Modern Geology.
James Hutton: Founder of Modern Geology.Courtesy Public domain (via Wikipedia)
Today is the 314th anniversary of the death of Scottish physician, naturalist, and geologist James Hutton. Born in 1726, Hutton is considered the founder of modern geology and best remembered for his theory of the rock cycle, and of uniformitarianism. His concept of deep time was groundbreaking in its day and shattered the popular Bible-based notion that the Earth was a mere 6000 years old. Hutton died on this date in 1797.

James Hutton biography

UPDATE: Here's an updated video showing the terrifying force of the tsunami that swept across the Japanese city of Sendai. It's not just an unstoppable wave; it's a juggernaut of debris.

8.9 magnitude earthquake hits Japan
8.9 magnitude earthquake hits JapanCourtesy USGS
A monster earthquake hit northern Japan today at 2:46pm local time (11:46pm CST) causing tremendous damage including the triggering of a deadly and devastating tsunami. The images of destruction coming out of the country are both stunning and heartbreaking. Early reports say a 30-foot wave slammed into the city of Sendai washing away houses, cars and other debris – some of it in flames. The city is located about 80 miles from the quake’s epicenter and has a population of over 1 million people. According to the USGS Earthquake site the tremblor occurred at a depth of about 15 miles. The initial shaking is reported to have lasted two minutes, and has been followed by several strong aftershocks. It’s the most powerful quake to hit Japan in 140 years, and there are already reports of 200-300 deaths. But unfortunately that will more than likely rise as time goes on and reports are updated. Tsunami warnings have been issued across much of the Pacific Rim and also Russia. Seven foot waves have already hit Hawaii.

NOAA's Tsunami Warning Center
USGS Earthquake center


Although it’s been in a constant state of eruption for nearly three decades, Kilauea volcano on the Big Island of Hawaii has upped the ante with the appearance of a new fissure that’s been tossing a spectacular spray of molten lava up to 80 feet into the air. Recent rockfalls from the widening vent have produced rumblings and popping sounds as blocks of rock as large as small cars have dropped into the rising lava lake. The US Geological Survey’s Hawaii Volcano Observatory has set up a web cam to monitor the volcano’s activity.

Eruption story
Collapsing vent story
Hawaii Volcano Observatory