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April 5, 2022
Real sandbox model meets “numerical sandbox” model…an interesting comparison of dry granular media and discrete element simulation
By Philip S. Prince Back in February, I saw several references to the CDEM discrete element modeling tool on Twitter. One of the example simulations reminded me of a “real” sandbox model I made a couple of years ago while experimenting with different material properties. The two results are shown below, with the CDEM example on the left and the real sand model on the right. The CDEM example above …
March 8, 2022
Lidar reveals geologic details of the “worst” coal mine in the Valley of Virginia
Despite its apparently good location, all was not well at the Altoona Mine. Coal seams in the mine were too distorted and mixed with surrounding rock to be easily extracted, leading to its ultimate failure. Early 20th century geologist Marius Campbell addresses this issue at length in the 1925 report The Valley Coal Fields of Virginia, twice calling Altoona’s location “the worst” in the general area and the obvious reason for the mine’s closure.
February 14, 2022
The waddling boulder…a storm-induced trundle* event?
This was (and remains) the first and only boulder I have personally seen that has rolled or tumbled and come to rest recently enough for its track to be visible in the field. I thought the diagonal gouge marks were particularly interesting. For whatever reason, they caused me to visualize a slow, “waddling” rolling style like that of an American football or rugby ball rolling downhill.
February 2, 2022
Fun with ice physics in the cryosphere
By Ned Rozell A recent winter storm that featured a heavy rainfall caused hardships for many animals of Interior Alaska, but some people found the event fascinating. Two men who live up here and study the cryosphere — the frozen and snow-covered portion of the Earth’s surface — squinted for a closer look at what the storm threw at us. When the snow-rain-snow storm began just after Christmas 2021, Matthew …
January 31, 2022
Midwinter rain-on-snow a game changer
By Ned Rozell A few hours of a December day may affect living things for years to come in the middle of Alaska. On Dec. 26, more than an inch of rain fell over a wide swath of the state. Much of the backcountry of Interior Alaska now has an ice sheet beneath a foot of fluffy snow. With half of the seven-month winter yet to come, things look grim …
The porcupine’s winter in slow-motion
By Ned Rozell While running through Bicentennial Park in Anchorage, biologist Jessy Coltrane spotted a porcupine in a birch tree. On her runs on days following, she saw it again and again, in good weather and bad. Over time, she knew which Alaska creature she wanted to study. “I thought, ‘Oh my god, how does he do it? How does this animal make it through winter?’” Coltrane said years ago …
January 25, 2022
Two mappings of a folded thrust fault in the Appalachian Valley and Ridge, 100 years apart
These klippen are made even more interesting by the fact that they were mapped and correctly interpreted in 1924. Comparing these maps separated by 98 years and considerable changes in land use, geologic exposure, tectonic understanding, and imaging technology is very interesting to me. The same patterns and structural relationships are obviously present in both to a high level of detail, which is impressive given the much larger scale of the 1924 map project.
January 10, 2022
Is this the steepest river in the Appalachian Mountains?
Topographic superlatives are almost always a bit arbitrary, and comparing river steepness is about as arbitrary as it gets. How long of a stretch of river needs to be considered? How big does a stream need to be in order to be considered a “river?” Since a vertical waterfall is the maximum steepness possible, is the biggest river with a freefalling waterfall the winner? How tall does the waterfall have to be? These questions all have merit…
January 4, 2022
Thirty years on semi-solid ground
By Ned Rozell At the end of this month, Vladimir Romanovsky will retire after 30 years as a professor and permafrost scientist at the University of Alaska Fairbanks’ Geophysical Institute. This comes at a time when people — finally — no longer squint at him with a puzzled look when he mentions what he studies. Permafrost is ground that has remained frozen through the heat of at least two summers. …
December 3, 2021
“Squirrel tail” synclines in the Appalachian Valley and Ridge
I settled on “squirrel tails” because Bartholomew and Lewis’ cross sections of the features reminded me of how a squirrel drapes its tail over its body and head. I am not sure if this is an effective comparison or not, but the overall approach seems to have served humans well when it comes to mentally organizing patterns of stars in the night sky. This structural style came across my radar after I mapped a similar type of structure ~25 miles (40 km) to the southwest, near the town of Max Meadows itself.
