Erosion on EARTH Magazine

After hurricanes, U.S. beach homes are rebuilt bigger

Tue, 19 Mar 2019 16:03:17 -0400

Debris from a damaged house in Hatteras, N.C., lies strewn on the ground after Hurricane Isabel hit the area in September 2003. Credit: Cynthia Hunter/FEMA.

When it comes to houses in the U.S., bigger is often seen as better. A new study looking at the recovery of real estate after major hurricanes has found that this trend also applies to beach houses rebuilt in vulnerable locations after damaging storms.

A rocky source of nitrogen

Tue, 03 Jul 2018 11:38:51 -0400

Calculations of the planet’s nitrogen balance have always been off: plants and soils seem to sequester far more nitrogen than expected. The atmosphere has long been thought of as the only major source of nitrogen, but a new study indicates an additional source: as much as a quarter of Earth’s terrestrial nitrogen may be supplied by eroding bedrock.

Benchmarks: May 3, 2003: New Hampshire's Old Man of the Mountain falls

Tue, 10 Apr 2018 10:06:18 -0400

New Hampshire's famed face-shaped outcrop of Conway Granite, known as the Old Man of the Mountain, shown in April 2003. It collapsed one month later. Credit: Jeffrey Joseph, public domain.

On May 2, 2003, the Old Man of the Mountain, New Hampshire’s famous face-shaped granite formation, adorned the side of Cannon Mountain in Franconia Notch State Park, just as it had for millennia. But by the next morning, it was gone: The iconic stone face had fallen.

Western wildfires affect water quality

Thu, 14 Dec 2017 17:50:55 -0500

Wildfires are likely to increase sediment loads in watersheds across the U.S. West, according to new research. In this false-color image taken Oct. 21, 2017, by the Terra satellite, areas burned (dark gray) by recent wildfires in the vicinity of Santa Rosa and Napa, Calif., can be seen amid living vegetation (red). Credit: NASA/METI/AIST/Japan Space Systems, and U.S./Japan ASTER Science Team.

Wildfires have burned increasing acreage in recent decades, a trend that’s expected to continue with global climate change. In the U.S. West, the frequency of fires has implications for water availability — both water used to fight wildfires and municipal water supplies, which can be contaminated by loosened debris from eroding, fire-burned slopes.

Red Planet Roundup: December 2017

Wed, 15 Nov 2017 14:58:41 -0500

NASA scientists produced a new map of Mars' crustal thickness based on a combined analysis of gravity and topographic data. The work suggests that the planet's crust is less dense on average and that variations in thickness between thicker (red) and thinner (blue) portions of crust are smaller than previously thought. Credit: NASA/Goddard/UMBC/MIT/E. Mazarico.

With two rovers patrolling the surface of Mars, six spacecraft orbiting above it, and scientists here on Earth studying the Red Planet from afar, new findings are announced often. Here are a few of the latest updates.

Red Planet Roundup: October 2017

Tue, 19 Sep 2017 11:45:46 -0400

A network of valleys, outlined in white, surrounds Lyot Crater in this computer-rendered illustration. New research suggests the water that carved these valleys likely melted from an ice sheet covering the area when an impact occurred. Credit: David Weiss/Brown/NASA.

Red Planet Roundup: August 2017

Wed, 19 Jul 2017 12:00:55 -0400

As Mars' atmosphere thinned early in its history, raindrops would have grown larger and fallen faster, affecting the planet's geomorphology — from crater rims to drainage valleys — in different ways at different times. Credit: Craddock and Lorenz, Icarus, April 2017.

Bottom dropping out of coral reefs

Mon, 17 Jul 2017 08:04:50 -0400

Fish swim amid a coral reef off Islamorada in the Florida Keys. Credit: Bethany Augliere.

Coral reefs provide habitat for 25 percent of all marine life, support fishing and tourism economies, and protect shorelines from surging waves and storms. But since the 1970s, coral populations have been waning because of warming waters, coastal development and pollution. Recently, scientists studying several beleaguered reef systems have discovered an unexpected consequence of their decline — the seafloor around the reefs is eroding, leaving coastal communities more vulnerable to high winds and waves.

Martian channels carved by lava, not water?

Mon, 19 Jun 2017 13:16:18 -0400

Part of Mangala Valles runs across the bottom of this image, which was taken with the High Resolution Stereo Camera aboard Mars Express in July 2015. (Note that north is to the right in the image.) Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO.

A complex system of river-like channels on Mars widely thought to have been formed by flowing water could instead have been carved by a huge lava flow, according to a new study. The findings could affect our understanding of how supportive Mars might have been for life in the past.

White Cliffs of Dover on the retreat

Mon, 20 Mar 2017 13:03:07 -0400

The White Cliffs of Dover. Credit: Martin Hurst.

England’s iconic White Cliffs of Dover tower 100 meters over the English Channel and, historically, were often the first and last view of England for sea-faring travelers. New research investigating the erosion history of the steep chalk cliffs suggests that they have been retreating far faster over the last 150 years than they once did.

Small floods can carve big canyons

Thu, 19 Jan 2017 13:41:27 -0500

Moses Coulee, amid the Channeled Scablands in Washington state, was carved by floods that burst from massive, naturally dammed glacial lakes during the last ice age. Credit: Williamborg.

Through the early 20th century, geologists argued over how the giant canyons of the Channeled Scablands in Eastern Washington were formed. Ultimately, a theory proposed by J Harlen Bretz in the 1920s — that the canyons were carved by catastrophic, short-lived outbursts of floodwaters unleashed when natural dams holding back glacial lakes collapsed — was shown to be correct. Controversy still exists, though, about the size of these ancient floods.

Fungi stabilize steep slopes

Wed, 18 Jan 2017 14:42:33 -0500

Researchers dug small terraces into the slope where rooted plants were placed. Credit: Alexander Bast.

The steep slopes of Switzerland’s high Alps are unstable — with loose soil and few plants — which poses hazards such as shallow landslides. In a new study, researchers have found that the symbiosis between plant roots and mycorrhizal fungi helps ground gravelly hillsides, suggesting a possible eco-engineering tool to stabilize the slopes.

Ice (Re)Cap: February 2016

Fri, 15 Jan 2016 08:33:28 -0500

Based on a study of New Zealand's Franz Josef Glacier, researchers have developed a novel numerical law to describe glacial erosion rates on Earth. Credit: Frédéric Herman.

From Antarctica to the Arctic; from polar caps, permafrost and glaciers to ocean-rafted sea ice; and from burly bears to cold-loving microbes, fascinating science is found in every nook and crevasse of Earth’s cryosphere, and new findings are announced often. Here are a few of the latest updates.

Wormholes may limit landslides

Fri, 06 Nov 2015 13:56:01 -0500

Puerto Rico's Luquillos Mountains appear in this photo taken from the International Space Station in 2007. (Note that north is down in the image.) Credit: NASA

Scientific investigations sometimes take unexpected twists and turns. When Emma Harrison, a graduate student at the University of Pennsylvania, began digging trenches in the mountains of Puerto Rico to study how the soil mantle responds to rapid changes in erosion, she couldn’t help but notice the worms.

Due diligence in river incision data

Mon, 02 Nov 2015 11:40:16 -0500

River terraces near Lees Ferry along the Colorado River between Arizona and Utah record how the river has cut and scoured the surrounding landscape. Credit: Joel Pederson.

As great equalizers of topography, rivers and streams whittle down landscapes by alternately scouring away broad flat swaths of sediment and rock, and incising deeply through them. If a landscape — a mountain range, for example — is being uplifted by tectonic forces, this whittling occurs even faster. River incision rates in particular are thus often used to infer past rates of rock uplift. But determining incision rates themselves is not clear-cut. In a new study in Geology, scientists look at one complicating factor in such calculations, what the authors call the “unappreciated effects of streambed elevation variability” on measuring river incision rates.

Sculpting the Alps

Fri, 04 Sep 2015 11:25:06 -0400

Above about 1,800 meters, the steepness of mountain slopes in the vicinity of the Mont Blanc Massif near Chamonix, France, tends to decrease with elevation. Credit: Lucas Joel.

Mountains typically get steeper the higher you climb. The European Alps are an exception: Beginning at altitudes between about 1,500 and 2,000 meters, most slopes in the range tend to become less steep with increased elevation. This is largely caused by ancient glaciers, which scoured away much of the rock from the tops of the Alps. However, the steepness of alpine slopes also decreases in areas beyond the reach of glaciers, although the reasons why have remained elusive. New research is revealing how tectonic and fluvial forces have also helped shape the Alps’ unusual topography.

Wind whips canyons into shape

Tue, 16 Jun 2015 13:39:02 -0400

Wind may dramatically reshape canyons, both on Earth and on Mars. Credit: Noah J. Finnegan.

As a force of nature, wind is usually afforded less respect than water. Sure, it can topple trees and, in extreme cases, peel roofs off houses. But it can’t carve mighty canyons like water can — or can it? A new study suggests that geologists may have underestimated wind’s role in shaping valleys in arid environments, both on Earth and on Mars.

Pre-settlement erosion rates illuminated

Tue, 12 May 2015 10:05:26 -0400

Researchers quantified background landscape erosion rates in the southeastern U.S. prior to European settlement by studying sediments along 10 major rivers, including the Dan River. Credit: ©MarmadukePercy, CC BY-SA 3.0.

Humans are one of the most powerful erosive agents on Earth, moving copious amounts of sediment to and fro, mainly through agriculture and development. But quantifying how much we actually move — often a necessary step for developing sustainable land management practices — hinges on determining erosion rates in an area before humans intervened. A new study using surface exposure dating to estimate pre-colonial erosion rates in the southeastern U.S. has now clarified the natural background rate in more detail than ever before, revealing the dramatic human impact on the regional landscape.

Yosemite's cliffs in retreat

Mon, 20 Apr 2015 10:38:20 -0400

This past winter, two athletes grabbed the world’s attention as they climbed up the sheer walls of Yosemite National Park’s El Capitan. But some geologists are more concerned with what falls down these precipitous faces — namely, rocks. Park geologist Greg Stock has developed a history of rockfalls in Yosemite valley dating back 15,000 years, which reveals how its cliffs have crumbled since glaciers disappeared at the end of the last ice age.

Gravity builds stone sculptures

Tue, 04 Nov 2014 10:03:17 -0500

New research suggests that the formation of sandstone arches, such as Wilson Arch just south of La Sal Junction, depends on gravity. Credit: Mary Caperton Morton.

Every visitor to Arches National Park in Utah wonders how the spectacular, seemingly improbable sandstone arches form, but although there are many hypotheses, testing different ideas in the field has proved all but impossible. Now a new modeling study suggests that while arches may seem to defy gravity, their formation actually depends on it.

Clues to limestone weathering written in Western Wall

Sun, 05 Oct 2014 20:01:52 -0400

Builders and masons take note: When it comes to the durability of limestone, grain size matters. New research combining field and lab data shows that fine-grained limestone is more susceptible than its coarser-grained cousins to a one-two punch of chemical and mechanical weathering. The findings, which arose in part from observations of Jerusalem’s historic Western Wall, could have implications for Earth’s carbon cycle and landscape — as well as for architectural preservation.

Tiny ants are heroic weathering agents

Thu, 02 Oct 2014 14:28:59 -0400

Over geologic timescales, weathering of silicate minerals — which account for more than 90 percent of all crustal rocks on Earth — plays a significant role in decreasing carbon dioxide in the atmosphere, as carbon dioxide is consumed in chemical weathering reactions and the resultant carbonate becomes sequestered in the form of limestone and dolomite.

Hurricane Ike sent Galveston's beaches out to sea

Thu, 05 Jan 2012 06:41:58 -0500

Waters rise in Galveston, Texas, as Hurricane Ike approaches. FEMA

On Sept. 12, 2008, Galveston was a picture-perfect seaside Texas town, with an extensive stretch of beach lined with beautiful homes. But a day later, when Hurricane Ike roared across Galveston Island, the storm surge flooded the barrier island, washing away houses, roads and tons of beach sand. Now researchers have figured out where all that sand went.