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Oceanus Procellarum, a vast dark patch visible on the western edge of the Moon's near side, has long been a source of mystery for planetary scientists.
Some have suggested that the “ocean of storms” is part of a giant basin formed by an asteroid impact early in the Moon's history. But new research published in Nature deals a pretty big blow to the impact theory.
The new study, based on data from NASA's GRAIL mission, found a series of linear gravitational anomalies forming a giant rectangle, nearly 1,600 miles across, running beneath the Procellarum region.
Those anomalies appear to be the remnants of ancient rifts in the Moon's crust, say the authors of the new study.
The rifts provided a vast “magma plumbing system” that flooded the region with volcanic lava between 3 and 4 billion years ago. That giant flux of lava solidified to form the dark basalts we see from Earth.
It's the shape of the underlying gravity anomalies that cast doubt on impact hypothesis, said Jim Head, the Louis and Elizabeth Scherck Distinguished Professor of Geological Sciences at Brown and one of the authors of the new paper.
“Instead of a central circular gravity anomaly like all other impact basins, at Procellarum we see these linear features forming this huge rectangle,” Head said. “This shape argues strongly for an internal origin and suggests internal forces.”
The research team, led by Jeffrey Andrews-Hanna of the Colorado School of Mines, suggests a new hypothesis for just what those internal forces may have been.
The process, the researchers believe, was driven by the geochemical composition of the Moon's crust in the Procellarum region.
Early in its history, the Moon is believed to have been entirely covered in molten magma, which slowly cooled to form the crust.
However, the Procellarum region is known to have a high concentration of uranium, thorium and potassium – radioactive elements that produce heat.
The researchers believe those elements may have caused Procellarum to cool and solidify after the rest of the crust had already cooled.
When Procellarum did finally cool, it shrank and pulled away from the surrounding crust, forming the giant rifts seen in the new data. Magma flowed into those rifts and flooded the region.
“We think this is a really good, testable alternative to the impact basin theory,” said Head. “Everything we see suggests that internal forces were critical in the formation of Procellarum.”
New mission, old debate
The familiar face of the Moon's near side is dominated by the lunar maria, the dark patches etched across the surface.
Most of the large circular features – like Mare Serenitatis (Sea of Serenity) and Mare Imbrium (Sea of Rains) – have been shown to be impact basins that later filled with volcanic lava, which eventually cooled to form the dark basalts.
Samples gathered during the Apollo missions, and data gathered by subsequent unmanned missions, helped to confirm that idea.
But the origin of Oceanus Procellarum remained up in the air, largely because it simply doesn't look like the known basins. It is shaped a bit like a horseshoe, while the other basins are round.
Procellarum also lacks surrounding mountains and radial grooves scoured by impact ejecta, both telltale signs of an impact basin.
Still, the idea that Procellarum was indeed formed by an impact surfaced in the mid-1970s. Proponents of the impact theory argued that Procellarum looked different simply because it was much older than the other basins.
Because of its age, the telltale mountains and grooves had been eroded away, and debris had partially filled the basin's midsection, giving it the horseshoe shape.
Finally settling the debate required a mission like GRAIL, Head said. The mission is led by Maria Zuber, who earned her Ph.D. at Brown and is now vice president of research at MIT.
The twin GRAIL spacecraft, which orbited the Moon in 2012, made detailed maps of the Moon's gravity. Those maps have revealed important details about the Moon's subsurface crust.
“It's like putting the crust under an X-ray,” Head said. “We can go into the subsurface and see what's there. And when you're looking at what could be very old features, that's what you have to do because signatures at the surface become degraded over time.”
Apollo 15 Commander David R. Scott, a visiting professor in the Department of Earth, Environmental, and Planetary Sciences at Brown, explored the Hadley-Apennine region at the edge of the Imbrium basin in 1971.
“Orbiting the Moon following our surface exploration, it was very clear that Oceanus Procellarum differed in many ways from the circular maria in terms of its volcanic and tectonic activity,” said Scott, who was not involved in this latest research. “After so many years of puzzling over this, GRAIL has now provided the data to show why it is so distinctly different.”
Head said the results from this study show the remarkable extent to which internal processes can alter the surface of a planetary body.
The data generated here will be helpful in understanding the evolution of other planets and moons, and aid in the continuing exploration of our own Moon.
MIDDLETOWN, Calif. – An early Friday morning crash near Middletown injured four people, with three of them taken to area hospitals.
The head-on crash, which occurred just before 6 a.m. on Highway 29 at Butts Canyon Road, involved two vehicles, a 1997 Saturn and a 2007 Ford, according to the California Highway Patrol's Clear Lake Area office.
Angel Villalobos, 59, of Clearlake was driving the Saturn southbound on Highway 29 and preparing to turn left onto Butts Canyon Road when he collided head-on with the Ford driven by 56-year-old Jeffrey Story of Hidden Valley Lake, who was traveling northbound, the CHP said.
Villalobos and his two passengers were injured, as was Story, according to the report.
Villalobos had moderate injuries, while his passenger Miguel Villalobos, 56, of Clearlake suffered major injuries, which the CHP said included a fractured vertebrae, as well as fractures to his ribs and sternum.
Both men were taken by REACH air ambulance to Santa Rosa Memorial Hospital, according to the CHP report.
The CHP said the other passenger in the Saturn, 71-year-old Andres Lozano, also of Clearlake, was taken to St. Helena Hospital Clear Lake for treatment of moderate injuries.
Story had minor injuries and was not transported, the CHP said.
The report noted that all four of the men were wearing their seat belts.
The CHP said the cause of the crash remains under investigation.
Email Elizabeth Larson at
CLEARLAKE, Calif. – Work has begun on a bike/pedestrian lane conversion project in the city of Clearlake.
Chrisp Co. began working on the project on Olympic Drive earlier this week.
City officials confirmed to Lake County News that the construction activity moves to Lakeshore Drive on Friday.
After finishing the conversion projects, Chrisp Co. will begin a citywide road restriping project.
In August the city awarded the company the contract for the restriping project, which will include the installation of reflective centerline markers.
City Engineer Bob Galusha said the project will significantly improve safety.
Highway Safety Improvement Program funds are paying for the restriping and conversion projects, Galusha said.
Email Denise Rockenstein at
LUCERNE, Calif. – The Lake County Regional Economic Development Committee announced that the Lake Leadership Summit scheduled for Friday, Oct. 10, at Marymount California University’s Lakeside campus is sold out.
An event waiting list is available at www.embracethelake.com ; individuals who submit their names through the Web site will be contacted should an opening occur.
The summit is designed for local business leaders, owners, and entrepreneurs who are interested in developing their business and in growing Lake County.
The event is limited to 100 participants and the sell-out is welcome news to committee organizers.
“There’s always some concern about ticket sales when a new event launches in Lake County. We’re pleased that our community embraced the Lake Leadership Summit with such enthusiasm. We’re creating a waiting list now for people who would like to participate in the event of last-minute cancellations,” said Wilda Shock, summit co-creator and economic development specialist for the city of Lakeport.
The summit features presenters from the state of Washington state and from the Bay Area who will speak about technology, customer service and economic development.
Optional activities designed to encourage summit participants to see Lake County with fresh eyes include a haunted walking tour of Lakeport, a “Pirate BootyCycle” tour of Kelseyville and a Lake County scavenger hunt by bus.
These activities are offered on the afternoon of the summit and are available for an additional fee to summit participants.
“We’ve been working on the summit for about a year now, refining the format, ensuring that we offer salient information along with some aspirational stories about what Lake County can become in the future,” said Alan Flora, deputy administrator for the county of Lake and summit.
The Lake Leadership Summit is sponsored by Pacific Gas and Eletric, St. Helena Hospital Clear Lake, the county of Lake, Sutter Lakeside Hospital, Mendo Lake Credit Union, Lake County Chamber of Commerce, and the Savings Bank of Mendocino County.
Generous support is being provided by Marymount California University, Sutter Lakeside Hospital, the county of Lake, CalRecycle, the cities of Clearlake and Lakeport, Featherbed Railroad Bed & Breakfast Resort, Lakeport English Inn, MPIC Inc. and Workforce Lake, Old World Tavern, Kelsey Creek Brewing Co., Hoberg’s Resort & Spa, Mendo Lake SUP and the Lakeport Senior Center Meals on Wheels Thrift Store in Lakeport.
Walla Walla Valley Chamber of Commerce, Sonoma County Tourism, and Focus Financial Partners also are providing support. Additional sponsors are welcome.
To add your name to the waiting list, go to www.embracethelake.com .
If you have questions, please call Rebecca Southwick at 707-349-8105 or write to
LAKE COUNTY, Calif. – Members of the Lake County Gang Task Force conducted a probation sweep last week that resulted in eight arrests.
On Sept. 25 agents from the Department of Homeland Security assisted the Lake County Gang Task Force with a probation sweep at numerous locations in Lake County, according to Lt. Steve Brooks o the Lake County Sheriff's Office.
The Lake County Gang Task Force consists of personnel from the Lake County Sheriff’s Office, Lake County Probation Department and the Clearlake Police Department.
The result of the operation led to the following eight arrests:
– Robert Lee Hayes, possession of concentrated cannabis, possession of marijuana for sale and probation violation;
– Delonna Ann Owens, possession of concentrated cannabis and possession of marijuana for sale;
– Desirae Naomi Deweese, possession of drug paraphernalia, under the influence of a controlled substance, willful cruelty to a child and violating the terms of her probation;
– Christopher Wayne Marks, child neglect and willful cruelty to a child;
– Ian Lee James, child neglect and willful cruelty to a child;
– Jeffrey William Dumas, possession of a controlled substance and warrants;
– Markus Carl Graham, possession of drug paraphernalia, possession of a controlled substance and violating the terms of his probation;
– Melvin Dean Jones, possession of drug paraphernalia, willful cruelty to a child and violating the terms of his probation.
All of the subjects who were arrested were transported to the Lake County Hill Road Correctional Facility and booked, Brooks said.
Brooks said six additional subjects were issued citations for being under the influence of a controlled substance and outstanding warrants.
The Sheriff’s Narcotics Task Force can be reached through its anonymous tip line at 707-263-3663.
NORTHERN CALIFORNIA – Caltrans and its contractors have begun work on six emergency contracts to repair damage caused by an Aug. 24 earthquake in Napa and Solano counties.
The agency said the repairs total $5.3 million.
Caltrans engineers and inspectors also continue to work with local agencies to assess and inspect damage affecting local bridges and structures.
Though no damage affecting public safety or the structural integrity of bridges resulted from the quake, the contracts will result in final repairs to 11 state-owned bridges including fixing bridge seals, spalled concrete, damaged pavement, curb cracking and damaged bridge rails at locations on Highways 29, 37 and 121 in Napa and Solano counties.
Work on an additional contract to repair pavement buckling on Highway 121 was completed within three days of the earthquake.
“One of Caltrans’ most critical tasks after an earthquake is to assess the impact on the state highway system’s bridges and roads,” said Caltrans Director Malcolm Dougherty. “In Napa, we were able to respond quickly thanks to seismic data which allowed us to prioritize our safety inspections of highways and bridges affected by the earthquake.”
Eight Caltrans building inspectors were also deployed to help the city of Vallejo, as only about 1,000 of 40,000 buildings in the city had been inspected for damage.
Caltrans inspectors completed more thorough followup inspections of buildings that had been initially tagged for caution and canvassed areas for safety assessments where inspections still remained.
The Caltrans teams also responded to calls from the public and fire and police departments to assess structural hazard concerns.
“In times of emergency, it’s all hands on deck to ensure the public’s safety, regardless of jurisdiction and responsibility,” continued Dougherty. “I’m proud of the Caltrans bridge and structural engineers and inspectors who were able to go out into the field to help Bay Area local governments and agencies assess the quake’s damage.”
Following the Napa earthquake, Caltrans used a rapid earthquake response tool called ShakeCast to identify which bridges may have experienced shaking.
ShakeCast uses ground sensors to analyze earthquake shaking and provides data to the U.S. Geological Survey in the aftermath of a quake that immediately allows Caltrans to prioritize inspections of bridges and structures.
Within 48 hours of the earthquake, Caltrans inspected all seven Bay Area toll bridges and no damage was found on any of those structures.
Caltrans bridge inspectors, working in four two-person teams, also inspected 29 state highway bridges in Napa, Solano and Contra Costa counties.
Minor damage was found on eight bridges consisting mainly of spalled concrete, damaged joints and barrier rail and some pavement settlement of the bridge approaches. All bridges are fully open, structurally sound and safe for traffic and public use.
At the request of the city of Napa, Caltrans assisted with local inspections of three city-owned structures, one at Third Street and two on Soscal Avenue.
Caltrans bridge inspectors also came to the aid of Napa County, inspecting 104 locally-owned bridges for any earthquake-related damage. As a result of these inspections, nine of these bridges were found to have sustained damage.
With the exception of the Garnett Creek Bridge north of Calistoga, which the county closed and will likely replace, damage to the bridges was minor and included concrete cracking and some settlement.
Total cost for repairing the damage to the locally owned bridges is estimated around $2.7 million.
