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Deep Beneath California’s Sierra Nevada, Earth’s Lithosphere May Be Peeling Away – Eos

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Deep Beneath California’s Sierra Nevada, Earth’s Lithosphere May Be Peeling Away – Eos


Source: Geophysical Research Letters

The processes that form continental crust from the denser basaltic rocks of the upper mantle may make the lower lithosphere denser than the underlying mantle. One theory holds that the lower lithosphere splits away and sinks into the mantle in a process called foundering. Conclusive evidence of foundering, however, has been hard to come by.

Peering deep under California’s Sierra Nevada, Schulte-Pelkum and Kilb discovered new evidence of lithospheric foundering in progress. The team imaged the lower crust and uppermost mantle beneath the Sierra Nevada with receiver function analysis, which uses seismic waves that change as they cross structures beneath the surface.

They also studied earthquake data from the Advanced National Seismic System Comprehensive Earthquake Catalog, or ComCat. They found a band of seismicity in the central Sierra, in which small earthquakes (ranging from magnitude 1.9 to 3.2) occur at the unusual depths of 40 kilometers and greater.

Differences in receiver functions along the mountain range revealed a distinct layer in the mantle, which grows gradually less distinct farther north. This aligns with the existing hypothesis that a section of the lithosphere beneath the southern Sierra sank (foundered) millions of years ago.

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A slab of colder continental lithosphere also has the capacity to crack, rather than to stretch and flow like hot material typically found at such depths. This likely also explains the presence of such deep earthquakes in the central Sierra, according to the authors.

The researchers found no evidence of this layer in the northern Sierra, indicating foundering has yet to progress to that region.

This work aligns with previous studies that found a gradient Moho, rather than a sharply defined crust-mantle boundary, under the Sierra. It also matches previous suggestions that a cold mantle anomaly under the Great Valley region to the west may be dense lithosphere lost to the foundering process. Foundering has been ongoing in the Sierra for at least 3 million years according to this hypothesis, and the researchers say it may be progressing northward. This region provides evidence of a process of differentiation that occurs throughout Earth’s crust, they argue. (Geophysical Research Letters, https://doi.org/10.1029/2024GL111290, 2024)

—Nathaniel Scharping (@nathanielscharp), Science Writer

Citation: Scharping, N. (2025), Deep beneath California’s Sierra Nevada, Earth’s lithosphere may be peeling away, Eos, 106, https://doi.org/10.1029/2025EO250020. Published on 17 January 2025.
Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.
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Oregon lands commitment from Nevada punter

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Oregon lands commitment from Nevada punter


Oregon has found its next Australian punter.

Bailey Ettridge, who averaged 44.66 yards on 47 punts at Nevada this season, committed to transfer to the Ducks on Sunday. He has three seasons of eligibility remaining.

From Lara, Australia, Ettridge had 15 punts over 50 yards and 18 inside opponents’ 20-yard lines this season. He also had two carries for 26 yards, both of which converted fourth downs.

Ettridge replaces James Ferguson-Reynolds, who is averaging 41.64 yards on 33 punts for UO this season. Ferguson-Reynolds and Ross James are both out of eligibility after the season.

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Ettridge is the first scholarship transfer to Oregon this offseason and his addition gives the Ducks 81 projected scholarship players in 2026. He is the lone punter presently on the roster.



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‘Winnemucca Day’ helps fuel Backus, Wolf Pack to 58-40 win over Utah State

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‘Winnemucca Day’ helps fuel Backus, Wolf Pack to 58-40 win over Utah State


RENO, Nev. (Nevada Athletics) – Nevada Women’s Basketball returned to Lawlor for the first game of 2026, hosting Utah State.

The Pack picked up its first conference win of the season with the 58-40 victory over the Aggies.

Freshmen showed out for the Pack (5-9, 1-3 MW) with Skylar Durley nearly recording a double-double, dropping 12 points and grabbing nine rebounds. Britain Backus had five points to go along with two rebounds and a season high four steals.

Junior Izzy Sullivan also had an impactful game with 17 points, going 6-for-11 from the paint and grabbing five boards. She also knocked down Nevada’s only two makes from beyond the arc, putting her within one for 100 career threes.

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The Pack opened up scoring the first four points, setting the tone for the game. It was a close battle through the first 10 as Utah State (6-7, 2-2 MW) closed the gap to one.

However, Nevada never let them in front for the entire 40 minutes.

Nevada turned up the pressure in the second quarter, holding Utah State to a shooting drought for over four minutes. Meanwhile, a 5-0 scoring run pushed the Pack to a 10-point lead.

For the entire first 20, Nevada held Utah State to just 26.7 percent from the floor and only nine percent from the arc, going only 1-for-11.

For the Pack offense, it shot 48 percent from the paint. Nevada fell into a slump coming out of the break, only scoring eight points.

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It was the only quarter where the Pack was outscored.

The fourth quarter saw the Pack get back into rhythm with a 6-0 run and forcing the Aggies into another long scoring drought of just under four and a half minutes.

Durley had a layup and jumper to help with securing the win.

Nevada will remain at home to face Wyoming on Wednesday at 6:30 p.m.

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EDITORIAL: Nevada’s House Democrats oppose permitting reform

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EDITORIAL: Nevada’s House Democrats oppose permitting reform


Politicians of both parties have promised to fix the nation’s broken permitting system. But those promises have not been kept, and the status quo prevails: longer timelines, higher costs and a regulatory maze that makes it nearly impossible to build major projects on schedule.

Last week, the House finally cut through the fog by passing the Standardizing Permitting and Expediting Economic Development Act. As Jeff Luse reported for Reason, the legislation is the clearest chance in years to overhaul a system that has spun out of control.

Notably, virtually every House Democrat — including Reps. Dina Titus, Susie Lee and Steven Horsford from Nevada — opted for the current regulatory morass.

The proposal addressed problems with the National Environmental Policy Act, which passed in the 1970s to promote transparency, but has grown into an anchor that drags down public and private investment. Mr. Luse notes that even after Congress streamlined the act in 2021, the average environmental impact statement takes 2.4 years to complete. That number speaks for itself and does not reflect the many reviews that stretch far beyond that already unreasonable timeline.

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The SPEED Act tackles these failures head on. It would codify recent Supreme Court guidance, expand the projects that do not require exhaustive review and set real expectations for federal agencies that too often slow-walk approvals. Most important, it puts long-overdue limits on litigation. Mr. Luse highlights the absurdity of the current six-year window for filing a lawsuit under the Environmental Policy Act. Between 2013 and 2022, these lawsuits delayed projects an average of 4.2 years.

While opponents insist the bill would silence communities, Mr. Luse notes that NEPA already includes multiple public hearings and comment periods. Also, the vast majority of lawsuits are not filed by members of the people who live near the projects. According to the Breakthrough Institute, 72 percent of NEPA lawsuits over the past decade came from national nonprofits. Only 16 percent were filed by local communities. The SPEED Act does not shut out the public. It reins in well-funded groups that can afford to stall projects indefinitely.

Some Democrats claim the bill panders to fossil fuel companies, while some Republicans fear it will accelerate renewable projects. As Mr. Luse explains, NEPA bottlenecks have held back wind, solar and transmission lines as often as they have slowed oil and gas. That is why the original SPEED Act won support from green energy groups and traditional energy producers.

Permitting reform is overdue, and lawmakers claim to understand that endless red tape hurts economic growth and environmental progress alike. The SPEED Act is the strongest permitting reform proposal in years. The Senate should approve it.

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