In a article on Phys, they report scientists have found clues in Alaska that has them rethinking how to continental crust forms based upon research published in Nature Geoscience.
A new study appearing in this week’s Nature Geoscience raises questions about one popular theory and provides new support for another, in which arc lava from the surface and shallow “plutons” – magma that solidified without erupting – are pulled down into the Earth at subduction zones and then rise up to accumulate at the bottom of the arc crust like steam on a kitchen ceiling. Scientists have found compelling evidence to suggest that this could have produced the vast majority of lower continental crust through Earth history.
The process, called relamination, starts at the edge of a continental plate, where an oceanic plate is diving under the continental plate and magma is rising to form a volcanic arc. As the oceanic plate dives, it drags down sediment, lava and plutonic rock from the edge of the arc. As arc material descends, minerals within it become unstable with the rising pressure and heat, and they undergo chemical changes. New minerals form, and chunks of the rock and sediment can break off. When those chunks are denser than the mantle rock around them, they continue to sink. But when they are less dense, such as those that form silica-rich granulites, they become buoyant and float upward until they reach the bottom of the arc crust and accumulate there.
Last year, OPB-TV won awards for their “Unprepared” television series and documentary on the historical “big one” coming to the Pacific Northwest. It led to discussions around the state of Oregon involving geologists, seismologists, and area experts, all asking if we are prepared and what are we going to do or not do about it. They talked about the state of our bridges, schools, and the impact of liquefaction on our ports, home to fuel tanks, some almost 100 years old, that could rupture, dump into our precious waterways, and burn for ages. It was a wake-up call for all of us.
Liquefaction is the process in which soil, often thought to be firm and solid, is “reduced” by earthquake shaking. While most commonly associated with saturated soils, liquefaction occurs in dry soils where there is space between the particles. Take a jar and fill it full of flour or grains. Tap it against the counter and you will see the level drop. Depending upon the space and shape of the grains, it might drop a little or a lot. That’s liquefaction in action. Continue reading “Cascadia Subduction Zone: Unprepared and Liquefaction”→
Recently, we have been able to provide some answers to the questions of how diverse through time has life been, based on the building of large fossil occurrence databases and new methods of analysing them. One such development has been the Paleobiology Database, a professional crowd-sourced archive of fossil history, where the context of fossils is provided in both space and time, and largely based on the published record of fossil discoveries.
…By applying SQS with our development of large fossil occurrence datasets, voila, we are able to gain renewed insight into the diversity of life through history in a way that accounts for the inherent biases of the fossil record!
And that’s just what a new study in PLOS Biology set out to do. Led by Roger Benson of the University of Oxford, an international team of researchers applied SQS to one of the largest tetrapod fossil occurrence databases ever assembled (if not the largest!), comprising more than 27,000 individual fossil occurrences! This represented almost 5000 fossil species, and the data were restricted to just those fossils that dwelled on land – so this excludes groups like ichthyosaurs and plesiosaurs, for example. They also excluded flying tetrapods, so birds, bats and mammals, as these are known to have very different preservational histories in the fossil record. For palaeontology though, this is definitely ‘big data’.
The team restricted their analyses to just the Mesozoic to early Paleogene, a time span of around 190 million years (a fairly long time, even by geological standards!). If you think about it, that’s 5000 species over about 190 million years, which compared to 30,000 around today is pretty weird even in itself.
There are real “rewards and recognition” for winners. Cash prizes defray production costs, an award certificate and pin are presented to the winners, and information about all winners is published in newsletters and magazines. But more important, each winning program is duplicated and distributed to the seven Regional Libraries,making the winning programs available to Clubs across the country — giving their members a chance to enjoy and learn from them for many years.
The group has contributed in the past, and it would be exciting to be recognized for some of our outstanding educators and programs.
The Competition recognizes and rewards authors of presentations about the Earth Sciences. The programs are then shared with other clubs across the country. The programs or presentations may consist of digital presentations (PowerPoint) and materials (PDF) or video, 30-40 minutes in length.
There are four classes for entries:
Hot to Do It
Just for Juniors (young people)
The judges are looking for:
Accuracy and educational value
Quality of photography and visuals
Completeness of Story (but not too much)
Narration that moves well from one image to the next
Explore an area of interest or demonstrate ideas and techniques for use
Well-crafted title, credits, and “the end” slides
The awards include $200 cash prize for the highest, $100 for other placements, and winners will be announced at the AFMS Awards Banquet.
If you are interested in entering the contest, let us know. We’d love to help you make it the best. Talk to a board member at the next meeting or contact us. For more information, check your latest AFMS newsletter.
The app is free and runs “silently” in the background. The app has the ability to distinguish between natural body and transportation movements and ground disturbances. The goal of the app is to collect enough data to help track earthquakes in a way that may lead to a global early warning system.
The app offers four key features in addition to collecting and transmitting earth movement data to Berkeley.
Recent: The Recent tab displays earthquake data globally with a magnitude of 2.5 or more within the past 7 days. Using a Google Map, the user may zoom around the globe to observer recent earthquake activity.
Safety: Simple steps to ensure the user is familiar with how to take cover before, during, and after an earthquake.
Senor: While mostly for fun, shake the phone around and you will see the phone’s senor record the movement.
Past: This is another Google Map highlighting the most powerful and noteworthy earthquakes throughout known history, some dating back hundreds of years.
We are still looking for volunteers and exhibitors, along with some other stuff for our upcoming Tualatin Valley Rock and Gem Show March 11-13. Time is short, so jump on these please. Rose Jackson has given us the following wish list for help. Please contact Rose Jackson or use our contact form to let us know if you are interested.
There is still room for exhibitors. If you would like to exhibit at the Rock and Gem Show, please fill out the TVRGC DISPLAY Application and send it in as soon as possible.
We are looking for Raffle prizes. These are the prizes show attendees buy tickets to win at the end of the show. So far there is only one raffle prize. Please make sure these prizes are items people would want to buy tickets to win. They do not need to be rock and mineral related.
Door prizes are also needed. These are won by show attendees when numbers are called during the show and their tickets match the called numbers. They don’t need to be expensive but something a person would be happy to select and own.
For all of you that have already signed up I want to thank you. Your help is much appreciated. There are still places that need to be filled in so during set-up, if you will be able to volunteer additional time during the show, please stop in the lunch room area where the sign-up sheets will be and add your name to a task.
Club Member Sales
If anyone is interested in selling a few items – finished items only, no rough materials – at the members sales table please notify me before show set-up. I will need a count on how many people are selling. Currently I have 3 people signed up for sales. Please don’t come to the show expecting to sell without contacting me in advance. Space is limited!
How club member sales work.
You have to mark all your items with some type of identification, price and include an inventory sheet listing your items for sale.
You will be giving 10% of your sale to the club.
All sales will be written on a receipt>
Pay out is after the show at the next following meeting.
If you have any questions, please contact Rose Jackson or use our contact form.
OPB-TV’s Oregon Experience honored Thomas Condon last week with his story. A preacher and pioneer geologist, Thomas Condon arrived in the Oregon Territory in 1853 and settled in The Dalles, and eventually became Oregon’s first state geologist and professor at Pacific University in Forest Grove, Oregon, and later to the brand new University of Oregon in 1876.
Thomas Condon always loved geology. He subscribed to scientific journals and collected rocks and fossils wherever he lived. Townspeople, teamsters, and soldiers stationed at Fort Dalles knew of his great knowledge of geology and began bringing him fossils to examine and identify.
By 1865 Condon was accompanying the soldiers on trips into Oregon’s interior and was the first to recognize the scientific significance of the area now known as the John Day Fossil Beds – where nearly 50 million years of time are preserved.
The mid 1800s was considered the Golden Age of Paleontology. Scientists were in competition to discover fossil specimens that would support Charles Darwin’s new theory of evolution. Early on Condon had began corresponding with prominent East coast paleontologists and sent them fossil specimens he’d collected for identification. The paleontologists in turn had the status and money to write articles and get the new discoveries published in leading scientific journals.
Some of Condon’s most famous ancient discoveries included parts of small three-toed ancestors of the modern horse. Yale University professor O.C. Marsh called the fossils the “missing link” in horse evolution and would write significant papers on the subject using Condon’s fossil discoveries as part of the evidence.