Courtesy Public domain via USGSBy studying magnetic and electrical data, geologists have found further evidence that the town of Decorah, Iowa is built upon an ancient impact crater created around 460 million years ago.
Courtesy Vkil via Wikipedia Creative CommonsDecorah is located in northeast Iowa near the Minnesota border about 150 miles south of Minneapolis. Scientists think the Decorah Impact Structure resulted from the same meteorite barrage - known as the Ordovician meteor event - that produced similarly-aged craters found in Oklahoma, Wisconsin, and the Slate Islands in Lake Superior. The Decorah crater lines up nicely with the others.
The first evidence that an ancient crater might exist under Decorah came in 2008 when well-drilling cores from the area collected and examined by Iowa's Department of Natural Resources and Geological and Water Survey indicated that a wide-ranging layer of an unusual type of shale set beneath the surface and encircled the town. Recent aerial geophysical measurements (both gravity and electrical magnetic) by the US Geological Survey and other agencies, including the Minnesota Geological Survey, affirmed the crater's existence.
The unusual shale layer is situated 50 feet under the bed of the Upper Iowa river and was probably deposited after the crater's creation when an ancient seaway invaded the area and filled in the basin with mud and sediment. Shocked quartz found in the rock layer directly beneath the shale adds further evidence that some sort of major impact took place. Shocked quartz is a highly stressed and shattered quartz produced only one of two ways: either by a bolide impact or from a nuclear blast. The impact that created the Decorah structure is estimated to have released the energy equal to the blast of 100 megatons of TNT. To put things in perspective, the nuclear bomb dropped on Hiroshima during World War II was equal to 15 kilotons of TNT. One megaton equals 1000 kilotons so the bolide blast in Decorah would have released the energy of more than 6500 Hiroshima bombs!
Paleobiologist Bevan French, an adjunct professor at the Smithsonian Institution's National Museum of Natural History studied quartz samples from the underlying layer of breccia and concluded they held characteristics indicative of an extra-terrestrial impact event.
When it slammed into Earth, the Decorah impactor created a 3.5 mile-in-diameter crater in the planet's surface and shattered existing layers of Early Ordovician and Cambrian rocks pushing them deeper underground. Several other meteor craters discovered on earth date back to around the same time period 450 to 470 million years ago, causing French to wonder if the Decorah crater should be included in that spike in impact frequency.
According to French the shale above the breccia layer is very well preserved and contains "a very fascinating biological assemblage,"which could also be of interest to paleontologists.
"Finding structures like these and being able to study them in the geological context," French said, "is going to yield a lot of very fascinating information about the relations between the terrestrial system and the extraterrestrial influences."
Courtesy Mark RyanHas past life on Earth been influenced by these impacts? If you consider the Chicxulub impact crater in the Yucatán Peninsula of Mexico and its alleged effect on non-avian dinosaurs at the end of the Cretaceous Period, you have to wonder if similar impact events weren't responsible for other extinctions and biological radiations during Earth's long history.
SOURCE and LINKS
We have lots of cool, clear water on our planet. But ever think about how it first got here? The folks at MinuteEarth have been thinking about that.
New materials seem to make an appearance at every Olympic Games, and this 2014 Winter Games is no exception. Materials and equipment can be a major factors in Olympic competitor's success or failure, and teams are always looking to get any advantage they can.
NBC's "Science of Sports" video series profiles a wide range of science and engineering topics related to this year's Winter Games ranging from the science of snow to advances in new materials.
The video, "Stability and Vibration Damping in Alpine Skiing"
describes how engineers are redesigning skis using nano materials to increase flexibility and stability. A University of Nevada, Reno mechanical engineering associate professor Kam Leang describes how he and his team are using nanocomposite materials to reduce unwanted vibration in high performance skis.
To read more about this research visit:
To learn more about nanotechnology, science, and engineering, visit:
To see other nano stories on Science Buzz tagged #nano visit:
Courtesy City of Saint PaulCome join us on Saturday, Feb. 8, noon to 4 p.m., to talk to the KAYSC Heritage Crew about the Sheffield Site at Northdale Recreation Center! We will be joined by Rod Johnson from the Minnesota Archaeology Society, and Dr Ann Merriman from Maritime Heritage Minnesota. North Dale Rec Center is located at 1414 Saint Albans Street, Saint Paul, MN.
Enter to win a 4 pack of tickets to Ultimate Dinosaurs, "a huge new exhibition featuring 20 fascinating specimens from the other side of the world". It will open at the Science Museum on March 1!
Go to http://www.smm.org/dinos for more information!
Courtesy Mark RyanOnce again it's time for Draw A Dinosaur Day.
Each year, on January 30th, anyone and everyone who loves dinosaurs is invited to draw a picture of their favorite and upload it to the official Draw A Dinosaur Day site. This is the 8th year for the annual event, and as I've boasted proudly before, it's also my birthday which I think is really great - and apropo - because like millions of other kids, I drew lots of dinosaur pictures in my younger years.
My drawing skills never really blossomed but I've enjoyed collecting vintage dinosaur artwork and paleontology illustrations done by others. Last summer, I had the good fortune of having some of my paleo-art collection put on display at the Minneapolis Institute of Arts as part of a collectors exhibition. What was really cool is that the curators included some of my grade school drawings of dinosaurs, including the one pictured here. So, grab your favorite drawing instrument, sketch out a picture of your favorite dinosaur, upload it to the site, and share it with the rest of the dinosaur renderers in the world. Remember, it's all for fun. Besides the official website, you can also view work done by other contributors on Flickr.
Draw A Dinosaur Day
Courtesy Mark RyanToday, on their Earth Observatory webpage, NASA has been nice enough to post a couple photographs of the Big Island of Hawaii, one taken from satellite on January 26, 2014 and the other from the International Space Station, snapped by an astronaut. I happen to be on the Big Island right now so I wanted to add a couple ground-level photos I took last evening at sunset. I hope my Minnesota friends don't hate me too much. They've been suffering under a Deep Freeze for the last couple weeks while I've been enjoying Hawaii's unbelievably beautiful weather. Just so they aren't too hateful, I'll mention that it did rain all day yesterday in Kailua-Kona where I'm located on the west side of the island. But just before sunset the clouds broke and produced one of the best sunsets I've seen here. And a rainbow was thrown in to boot. I've endured Minnesota winters for just about every year of my life so I don't feel at all guilty that I'm not enduring the current one. Aloha!
Earth Observatory webpage
Sure you've been cold during these polar vortexes. But what about that tree in your front yard? Thanks to the folks at MinuteEarth, you can learn how it's adapted to be able to survive this harsh weather.
At the Sheffield site we encountered many different kinds of lithic material that the Oneota used at this site. As we sort through our findings there are multiple different types of lithic material that have been identified. Lithics are stone artifacts and it consists of items such as stone tools or stone flakes. There were fragments of all different colors and luster and density to them. Going through all these different kinds of tools and flakes may lead someone to think: “Where did these rocks come from?”
The most common lithic we found at Sheffield was Prairie Du Chien Chert, which makes sense because quarries can be found throughout the southeastern part of Minnesota. Another kind of lithic material we found was Tongue River Silica and this rock can be found on the western side of Minnesota. One stone that was particularly interesting to me though is Hixton Orthoquartzite since it is sparkly. We believed the lithic material made of Hixton came from quarries in west Wisconsin.
These are just three of the many lithic materials we found at Sheffield, these lithic materials are significant because of where they originate from. The Sheffield site is located along the Saint Croix River which acted as a means for transportation. Did the Oneota move from place to place and collected these rocks in their travels?
Lithics are an important part in archaeology and not just because the tools made from them look cool. The material that makes up the stone can have as much information as how the lithic material was made into a stone tool. We are not just looking at rocks, but the more we know about what types of material were being used the more we might know about the people who lived at Sheffield.
Courtesy www.instructables.comHey there! Do you know that food can be cooked in the ground? Well it can! We learned about the process at the Archaeology Festival in Mille-Lacs Kathio State Park. This method of cooking was used by cultures over hundreds of years ago. Here are the steps that are similar to what we learned at Mille-Lacs Kathio State Park:
1.) Dig the hole on flat land and make sure there are no low hanging tree branches. Sandy areas work too. How big the hole will be is determined by size of the fire, and what you are going to cook. The hole should be about 3 feet deep.
2.) Line up the hole with medium or flat rocks on the sides and on the base.
3.) Next, it’s time to build the fire! Collect some dry wood. Put the larger branches on the base which will be the main fuel for the fire, and place smaller ones, like twigs or sticks, on top of it.
4.) When you fire it, let it sit for 2 hours so the stones can get hot and ready for cooking. If you run out of wood, you can use charcoals to keep the fire going.
5.) During those 2 hours, you can go prepare and season the food that you’re going to cook in your pit!
6.) Wrap the food with layers of aluminum foil, enough so that dirt won’t be able to sweep through. You can also use an oven pan or any other pots that are oven safe.
7.) After 2 hours, and the stones are heated up, remove half of the burning coals out of the pit and put them on the side for the next step.
8.) Place your food on top of the coals in the pit and then put coals that you took out around its sides.
9.) After that you cover it with dirt. Make sure to make a mound on the top, so you won’t lose its location.
10.) Depending on what you’re cooking, it’ll take awhile for it to get fully cooked, including vegetables. Depending on the size, it can take up to 12 hours. Look up the time it’ll take for the food to get cooked before doing this!
11.) When it’s time to take the food out, carefully dig the dirt and rocks out and make sure not to hit the food by accident or it’ll probably get ruined! It’s also very hot!
12.) Enjoy your food!
13.) Also remember to clean up the pit the next day by removing any scraps of aluminum foil and fill in the pit back with dirt. It’s very important!
If you plan to do this, stay safe!
If you want to check out on upcoming archaeology events. You can find the calenders on the Minnesota Archaeological Society website: http://mnarchsociety.org/events.html
Courtesy BksimonbThere's a new possible factor to the rapid collapse of honey bee population numbers. And tobacco plays a role; but the impacted bees aren't smoking.
New research shows that a rapidly mutating plant virus, called the tobacco ringspot virus (TRSV), may be at play in the high fatality rates in bee population numbers. This new virus behaves very similarly to the HIV virus in that it rapidly mutates to evade the immune systems of the honey bees. Evidence of TRSV has been showing up in many dead honeybees.
It's one new piece of the puzzle researchers trying to solve this mystery now can look at. Other factors that appear to be killing honey bees at high rates are new agricultural pesticides, a specific species of mites, the Israeli paralytic virus (IASV) and the loss of open wilderness.
Last winter, one third of honey bees died, a 42-percent increase over the regular winter death rates of 10-15 percent.
What do you think of this new theory? Share your thoughts by leaving a comment here for other Science Buzz readers.