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Building a statewide inventory of landslides in Arizona

Landslide data included in AzSLID AZGS's ' Building a Statewide Inventory of Landslides in Arizona' is now available on line courtesy of the North American Symposium on Landslides and AEG. More Summary

High Water Across the West: Rye Patch Dam and the Humboldt Sink

Rye Patch Dam on April 19th. The water in Rye Patch Reservoir is high, but not at the high water mark that can be seen just past the spillway. I'm moving slowly on this mini-series about the Humboldt River while working essentially 12-hour...Show More Summary

Brooklyn Landing, Brooklyn Creek

The first Western inhabitants of this area, the Peralta family, were horse people rather than boat people. They did much of their business, with the mission and the town of San Jose in the South Bay, by land. When they did use boats, it was to transport hides and tallow from their ranch, using an […]

Hitting the Road in the Best Way: Into the Pacific Northwest, and With My Students!

5 months agoAcademics / Geology : Geotripper

It's the time of year I love the most, our field season, when my students and I hit the road. We are making a grand loop, heading north along the spine of the Cascades, with stops at Mt. Shasta, Lava Beds, Crater Lake (above), St. Helens, and Mt. Show More Summary

Oakland builders, what are you thinking?

Californians have always known we’re prone to earthquakes. The first Californians didn’t have our worries about it, though, because their structures were small and limber, no larger than a temescal sweathouse. Things changed when the missionaries of New Spain came into the country starting in the late 1700s. When the earthquake of 8 December 1812 […]

Volcanoes in Hawai'i: Rock Finds a Way (to destroy life)

5 months agoAcademics / Geology : Geotripper

The summit of Mauna Kea in the distance, and the forested lower slopes of Mauna Loa in the foreground My last entry on the geological drama of Hawai'i concerned the stubbornness of life in a harsh volcanic environment, such as that which is found on the highest slopes of Mauna Loa and Mauna Kea on the Big Island of Hawai'i. Show More Summary

Liveblogging the Deluge: Before and Almost After

5 months agoAcademics / Geology : Geotripper

Tuolumne River on Feb. 21, 2017, discharge about 16,000 cubic feet per second There is no doubt that this has been a unique year for the rivers of California, one that could very well not be repeated in many of our lifetimes. A year ago we were in the grips of the worst drought ever recorded, five years running, and then the rains began. Show More Summary

Volcanic Flows in Hawai'i: Life Finds a Way (to destroy rocks)

6 months agoAcademics / Geology : Geotripper

Ohi'a Lehua (Metrosideros polymorpha) clinging to a crack in a 1974 lava flow on Kilauea I had kind of a schizophrenic (split-brain) response in regards to what I wanted to accomplish with this post. A couple of weeks ago while still...Show More Summary

Fluid-rock interaction is decisive for the formation of tungsten deposits

Tungsten mineralization is typically associated with reduced granitic magmas of crustal origin. While this type of magmatism is widespread, economic tungsten deposits are highly localized, with ~90% produced from only three countries worldwide. Show More Summary

10Be dating of late Pleistocene megafloods and Cordilleran Ice Sheet retreat in the northwestern United States

During the late Pleistocene, multiple floods from drainage of glacial Lake Missoula further eroded a vast anastomosing network of bedrock channels, coulees, and cataracts, forming the Channeled Scabland of eastern Washington State (United States). Show More Summary

The onset of the Dead Sea transform based on calcite age-strain analyses

The onset and evolution of the Dead Sea transform are re-evaluated based on new in situ U-Pb dating and strain analyses of mechanically twinned calcites. Direct dating of 30 syn-faulting calcites from 10 different inactive fault strands...Show More Summary

Did Paleo-Tethyan anoxia kill arc magma fertility for porphyry copper formation?

The Tethyan orogen is host to numerous porphyry Cu ± Mo ± Au deposits, but the majority formed during subduction of the Neo-Tethyan ocean basin in the late Mesozoic–Cenozoic; very few deposits have been found associated with Paleo-Tethyan subduction. Show More Summary

Biological memory of the first Pleistocene glaciation in New Zealand

Living species retain memories of their evolutionary history in their DNA, and that evolutionary history commonly reflects distinct geological events, such as mountain building and glaciation. We synthesize previously documented genetic...Show More Summary

Magma sheets defined with magnetic susceptibility in the Maiden Creek sill, Henry Mountains, Utah, USA

In the ~20-m-thick Maiden Creek sill of the Henry Mountains (Utah, USA) intrusive complex, 2 magma sheets are locally separated by a 1.5-m-thick lens of sandstone. We studied the boundary between these sheets at the termination of this...Show More Summary

A triple S-shaped compositional profile in a Karoo dolerite sill--Evidence of concurrent multiple fractionation processes

Thick dolerite sills show a range of vertical geochemical variation trends attributable to various processes during slow crystallization. We have identified chemical parameters in a 169-m-thick sill from the Karoo igneous province in...Show More Summary

Precarious ephemeral refugia during the earliest Triassic

The term refuge describes, in both ecology and paleoecology, an ecosystem that acts as a sanctuary during times of environmental stress. This study tests the concept by examining the fate of a single community that lived ~50 k.y. after the end-Permian mass extinction (EPME). Show More Summary

Biotic effects on oxygen consumption during weathering: Implications for the second rise of oxygen

The oxygen concentration of the atmosphere likely increased substantially in the late Neoproterozoic. Although several studies have presented compelling geochemical evidence for this stepwise oxygenation, few have addressed the mechanisms behind it. Show More Summary

Persistence of a freshwater surface ocean after a snowball Earth

Geochemical data from cap carbonates deposited above Cryogenian glacial deposits have been widely used to infer the conditions that prevailed in the aftermath of snowball Earth. However, the time scale over which these carbonates were...Show More Summary

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