A view of the Boulder Mountains from US-12 west of Helena. These mountains lie at the north end of the Boulder Batholith.
Alex Demas (Former Employee)
(He/him)Science and Products
Louisiana Public Awareness, Hydrologic Studies, and Hydrologic Data
Seeking the Seeps
A view of the Boulder Mountains from US-12 west of Helena. These mountains lie at the north end of the Boulder Batholith.
The anomaly at Pennington Mountain is visible in the geophysical data collected in aerial surveys conducted in 2021.
The anomaly at Pennington Mountain is visible in the geophysical data collected in aerial surveys conducted in 2021.
A fine-grained volcanic rock (trachyte) that hosts rare earth elements, niobium, and zirconium, all which are considered critical mineral resources. This rock was found on Pennington Mountain in Maine. Image courtesy of Chunzeng Wang, University of Maine-Presque Isle.
A fine-grained volcanic rock (trachyte) that hosts rare earth elements, niobium, and zirconium, all which are considered critical mineral resources. This rock was found on Pennington Mountain in Maine. Image courtesy of Chunzeng Wang, University of Maine-Presque Isle.
Geologists in the field at Pennington Mountain. The orange instrument is a portable gamma spectrometer. University of Maine-Presque Isle professor Chunzeng Wang (the lead author) is in front, Preston Bass is carrying the meter.
Geologists in the field at Pennington Mountain. The orange instrument is a portable gamma spectrometer. University of Maine-Presque Isle professor Chunzeng Wang (the lead author) is in front, Preston Bass is carrying the meter.
A view of the Grand Canyon, with the Great Unconformity visible. Credit: Alex Demas, USGS.
A view of the Grand Canyon, with the Great Unconformity visible. Credit: Alex Demas, USGS.
USGS Scientists Dan Kroes and Charlie Demas set out into the Atchafalaya Basin to inspect flooding conditions in the Basin.
USGS Scientists Dan Kroes and Charlie Demas set out into the Atchafalaya Basin to inspect flooding conditions in the Basin.
One of the more unfortunate ecosystem side-effects of the floodwaters as they move through the Atchafalaya Basin is they help spread some uninvited guests.
This is the invasive aquatic plant known as giant salvinia (salvinia molesta). It may not look big here, but trust us, it can carpet a lake or bayou.
One of the more unfortunate ecosystem side-effects of the floodwaters as they move through the Atchafalaya Basin is they help spread some uninvited guests.
This is the invasive aquatic plant known as giant salvinia (salvinia molesta). It may not look big here, but trust us, it can carpet a lake or bayou.
USGS scientists Dan Kroes and Charlie Demas took local Congressional staffers into the Atchafalaya Basin to show them the effects of the flooding on the Basin.
USGS scientists Dan Kroes and Charlie Demas took local Congressional staffers into the Atchafalaya Basin to show them the effects of the flooding on the Basin.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
USGS sets out to measure streamflow on the Mississippi River at Baton Rouge, sailing past the USS Kidd, a World War II destroyer.
USGS sets out to measure streamflow on the Mississippi River at Baton Rouge, sailing past the USS Kidd, a World War II destroyer.
A panorama of a flooded stand of cypress trees in the Atchafalaya Basin.
A panorama of a flooded stand of cypress trees in the Atchafalaya Basin.
As the Atchafalaya River spreads out through the Basin, the waters slow down, and the sediment falls to the river and lakebottoms. Over time, that sediment can build up, eventually choking the river or permanently closing the lake. Or, as more and more sediment piles up, it compacts, sinking deeper during a process known as subsidence.
As the Atchafalaya River spreads out through the Basin, the waters slow down, and the sediment falls to the river and lakebottoms. Over time, that sediment can build up, eventually choking the river or permanently closing the lake. Or, as more and more sediment piles up, it compacts, sinking deeper during a process known as subsidence.
Watch your hands! Here you can see one of the many denizens of the swamp that mistake our sensor and gauge houses for prime real estate. As Dan Kroes, the scientist monitoring subsidence, said, "At least it wasn't wasps this time..."
Watch your hands! Here you can see one of the many denizens of the swamp that mistake our sensor and gauge houses for prime real estate. As Dan Kroes, the scientist monitoring subsidence, said, "At least it wasn't wasps this time..."
USGS scientist Dan Kroes checks a subsidence instrument. Normally, this area is either barely under water or completely dry. The instrument is housed at around 7 or 8 feet, and there was just 16 inches between the sensor and water.
USGS scientist Dan Kroes checks a subsidence instrument. Normally, this area is either barely under water or completely dry. The instrument is housed at around 7 or 8 feet, and there was just 16 inches between the sensor and water.
This is the Mississippi River at Vicksburg, Mississippi, as the crest from the earlier flooding moves through.
This is the Mississippi River at Vicksburg, Mississippi, as the crest from the earlier flooding moves through.
Image shows a night-time view of the Natchez-Vidalia Bridge at Natchez, Mississippi.
Image shows a night-time view of the Natchez-Vidalia Bridge at Natchez, Mississippi.
USGS National Flood Coordinator Bob Holmes stands on one of USGS' boats in Vicksburg, Mississippi. This particular boat came from the USGS Indiana/Kentucky Water Science Center. The boat and its crew joined USGS scientists and boats from Alabama, Louisiana, and Mississippi in Vicksburg for the flood measurements.
USGS National Flood Coordinator Bob Holmes stands on one of USGS' boats in Vicksburg, Mississippi. This particular boat came from the USGS Indiana/Kentucky Water Science Center. The boat and its crew joined USGS scientists and boats from Alabama, Louisiana, and Mississippi in Vicksburg for the flood measurements.
USGS scientist Tammy Caudle demonstrates the acoustic dopplar current profiler onboard that will be used to measure streamflow on the Mississippi River.
USGS scientist Tammy Caudle demonstrates the acoustic dopplar current profiler onboard that will be used to measure streamflow on the Mississippi River.
Science and Products
Louisiana Public Awareness, Hydrologic Studies, and Hydrologic Data
Seeking the Seeps
A view of the Boulder Mountains from US-12 west of Helena. These mountains lie at the north end of the Boulder Batholith.
A view of the Boulder Mountains from US-12 west of Helena. These mountains lie at the north end of the Boulder Batholith.
The anomaly at Pennington Mountain is visible in the geophysical data collected in aerial surveys conducted in 2021.
The anomaly at Pennington Mountain is visible in the geophysical data collected in aerial surveys conducted in 2021.
A fine-grained volcanic rock (trachyte) that hosts rare earth elements, niobium, and zirconium, all which are considered critical mineral resources. This rock was found on Pennington Mountain in Maine. Image courtesy of Chunzeng Wang, University of Maine-Presque Isle.
A fine-grained volcanic rock (trachyte) that hosts rare earth elements, niobium, and zirconium, all which are considered critical mineral resources. This rock was found on Pennington Mountain in Maine. Image courtesy of Chunzeng Wang, University of Maine-Presque Isle.
Geologists in the field at Pennington Mountain. The orange instrument is a portable gamma spectrometer. University of Maine-Presque Isle professor Chunzeng Wang (the lead author) is in front, Preston Bass is carrying the meter.
Geologists in the field at Pennington Mountain. The orange instrument is a portable gamma spectrometer. University of Maine-Presque Isle professor Chunzeng Wang (the lead author) is in front, Preston Bass is carrying the meter.
A view of the Grand Canyon, with the Great Unconformity visible. Credit: Alex Demas, USGS.
A view of the Grand Canyon, with the Great Unconformity visible. Credit: Alex Demas, USGS.
USGS Scientists Dan Kroes and Charlie Demas set out into the Atchafalaya Basin to inspect flooding conditions in the Basin.
USGS Scientists Dan Kroes and Charlie Demas set out into the Atchafalaya Basin to inspect flooding conditions in the Basin.
One of the more unfortunate ecosystem side-effects of the floodwaters as they move through the Atchafalaya Basin is they help spread some uninvited guests.
This is the invasive aquatic plant known as giant salvinia (salvinia molesta). It may not look big here, but trust us, it can carpet a lake or bayou.
One of the more unfortunate ecosystem side-effects of the floodwaters as they move through the Atchafalaya Basin is they help spread some uninvited guests.
This is the invasive aquatic plant known as giant salvinia (salvinia molesta). It may not look big here, but trust us, it can carpet a lake or bayou.
USGS scientists Dan Kroes and Charlie Demas took local Congressional staffers into the Atchafalaya Basin to show them the effects of the flooding on the Basin.
USGS scientists Dan Kroes and Charlie Demas took local Congressional staffers into the Atchafalaya Basin to show them the effects of the flooding on the Basin.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
In late 2015/early 2016 unusually large rainfall in the Upper Mississippi River Valley led to significant flooding in Arkansas, Illinois, Louisiana, Mississippi, Missouri, and Tennessee. USGS crews responded to the flooding by collecting streamflow and water quality information and providing it to emergency responders.
USGS sets out to measure streamflow on the Mississippi River at Baton Rouge, sailing past the USS Kidd, a World War II destroyer.
USGS sets out to measure streamflow on the Mississippi River at Baton Rouge, sailing past the USS Kidd, a World War II destroyer.
A panorama of a flooded stand of cypress trees in the Atchafalaya Basin.
A panorama of a flooded stand of cypress trees in the Atchafalaya Basin.
As the Atchafalaya River spreads out through the Basin, the waters slow down, and the sediment falls to the river and lakebottoms. Over time, that sediment can build up, eventually choking the river or permanently closing the lake. Or, as more and more sediment piles up, it compacts, sinking deeper during a process known as subsidence.
As the Atchafalaya River spreads out through the Basin, the waters slow down, and the sediment falls to the river and lakebottoms. Over time, that sediment can build up, eventually choking the river or permanently closing the lake. Or, as more and more sediment piles up, it compacts, sinking deeper during a process known as subsidence.
Watch your hands! Here you can see one of the many denizens of the swamp that mistake our sensor and gauge houses for prime real estate. As Dan Kroes, the scientist monitoring subsidence, said, "At least it wasn't wasps this time..."
Watch your hands! Here you can see one of the many denizens of the swamp that mistake our sensor and gauge houses for prime real estate. As Dan Kroes, the scientist monitoring subsidence, said, "At least it wasn't wasps this time..."
USGS scientist Dan Kroes checks a subsidence instrument. Normally, this area is either barely under water or completely dry. The instrument is housed at around 7 or 8 feet, and there was just 16 inches between the sensor and water.
USGS scientist Dan Kroes checks a subsidence instrument. Normally, this area is either barely under water or completely dry. The instrument is housed at around 7 or 8 feet, and there was just 16 inches between the sensor and water.
This is the Mississippi River at Vicksburg, Mississippi, as the crest from the earlier flooding moves through.
This is the Mississippi River at Vicksburg, Mississippi, as the crest from the earlier flooding moves through.
Image shows a night-time view of the Natchez-Vidalia Bridge at Natchez, Mississippi.
Image shows a night-time view of the Natchez-Vidalia Bridge at Natchez, Mississippi.
USGS National Flood Coordinator Bob Holmes stands on one of USGS' boats in Vicksburg, Mississippi. This particular boat came from the USGS Indiana/Kentucky Water Science Center. The boat and its crew joined USGS scientists and boats from Alabama, Louisiana, and Mississippi in Vicksburg for the flood measurements.
USGS National Flood Coordinator Bob Holmes stands on one of USGS' boats in Vicksburg, Mississippi. This particular boat came from the USGS Indiana/Kentucky Water Science Center. The boat and its crew joined USGS scientists and boats from Alabama, Louisiana, and Mississippi in Vicksburg for the flood measurements.
USGS scientist Tammy Caudle demonstrates the acoustic dopplar current profiler onboard that will be used to measure streamflow on the Mississippi River.
USGS scientist Tammy Caudle demonstrates the acoustic dopplar current profiler onboard that will be used to measure streamflow on the Mississippi River.