One Of The Largest Icebergs On Record In The Making

A very large crack is forming in the Larsen C Ice Shelf on the Antarctic Peninsula. The crack is up to 1,500 feet wide and will most likely generate one of the largest icebergs on record. Only 6.4 miles of ice are keeping the ice sheet from calving off an iceberg that is basically the size of Delaware. Researchers who have been studying the ice melt (Project MIDAS) estimate that although the exact timing of the calving event in unclear, it could occur easily within the next few months. In fact, scientists noted that the crack spread another approximately six miles during the second half of December 2016. From January 1st to January 19th, the crack expanded again, and now only 6.4 miles of unbroken ice remains. Once the calving event occurs, scientists are concerned that it will destabilize the Larsen C ice sheet to the point of its disintegration.

The current location of the rift on Larsen C, as of January 19, 2017. Labels highlight significant jumps. Tip positions are derived from Landsat (USGS) and Sentinel-1 InSAR (ESA) data. Background image blends BEDMAP2 Elevation (BAS) with MODIS MOA2009 Image mosaic (NSIDC). Other data from SCAR ADD and OSM (update on graphic from Freedman, based on Project MIDAS data).

British Antarctic Survey (BAS) recently captured the following video footage of the immense crack in the Larsen C Ice Shelf:

Are All World Maps Wrong?

Geoawesomeness got my attention today by featuring a You Tube video done by Vox folks a few months ago. The Vox video points out that basically all world maps are wrong in how projections of land masses are variously shown. Aleks Buczkowski from Geoawesomeness gave a lead-in to the Vox video in his posting on it by saying:

Projecting a round surface of the Earth on a flat surface is not an easy task. Scientists are trying to find an optimal way to do it for centuries. In fact the most common map projection that we use almost everyday in Google Maps and other mapping services, has been introduced in 1569 by Gerardus Mercator.

The video from Vox does help to explain the intricacies of map projections and is really worth watching:

Winter Trekking Through Yellowstone’s Thermal and Glacial Features

Cross country skiing in one of the glacial melt-water channels on the Blacktail Plateau.

Some winter days in Yellowstone National Park are so amazing with clear blue skies and sparkling snow that they just take your breathe away. Luckily enough, I just experienced several of these kinds of days which I packed full of cross country skiing, snowshoeing, and animal watching.

One of the groomed trails that held a good snow base until about early afternoon is the Blacktail Plateau Loop. The trail follows melt-water channels that are associated with “Retreat Lake”, which was formed by the Beartooth glacial ice mass blocking the lower end of the Grand Canyon of the Yellowstone during the Pleistocene.

Rounded cobbles and boulders left behind from melt-water flow sit on the volcanic bedrock in many areas along the trail. Ski tip in the lower right for scale.
Looking back to the northwest on the Blacktail Plateau ski trail. Notice the scoop-shape of the landscape which is the result of this area being part of a glacial melt-water channel.
Calcite Springs overlook is accessible during the winter via the Tower ski trail.

The Tower ski trail provides access to the Grand Canyon of the Yellowstone area. A favorite stop of mine is the Calcite Springs overlook where the thermal springs lie south of the overlook, on the west side of the Yellowstone River and Pliocene/Pleistocene sediment and basalt are on the Yellowstone River’s east side.

 

A groomed ski trail also accesses the Upper Terraces of Mammoth Hot Springs. However, after a few days of spring-like temperatures, the snow was so melted back that I just used my snowshoes to trek through the icy slush.  Some thermal features were still covered by snow and slush, but others appeared much more vibrant against the white snow/slush blanket.

One of the fissure ridges along the upper Terraces trail is called White Elephant Back Springs and Terrace.

Aphrodite Terraces lie a short way north of the White Elephant Back Springs:

My favorite thermal feature of the Upper Terraces is Orange Spring Mound. The spring is supported by a fissure ridge and is intermittently active. Because of its low water discharge and subsequent slow growth, it has built up a characteristic cone shape.

Orange Spring Mound of the Upper Terraces in Mammoth Hot Springs.

All in all, it was perfect wintertime fun trekking around in Yellowstone. Can’t wait to get back there when the bears come back out from hibernation!

 

Cenozoic Sequence Stratigraphy of Southwestern Montana

Much of my research has been focused on Cenozoic sequence stratigraphy of continental basin-fill in southwestern Montana. This approach to the stratigraphy of continental deposits has facilitated correlation of stratigraphic units both within and among the various basins of this area. I recently gave a talk about my work in this area at Montana Tech of the University of Montana. Here’s the You Tube version of my talk:

Global Earthquakes 2001 to 2015: NOAA Science on a Sphere Animation

NOAA’s SOS data center has a new earthquake data set animation for events that occurred from 2001 through 2015. The Science on a Sphere’s animation shown above is described on their web site as:

This animation shows every recorded earthquake in sequence as they occurred from January 1, 2001, through December 31, 2015, at a rate of 30 days per second. The earthquake hypocenters first appear as flashes then remain as colored circles before shrinking with time so as not to obscure subsequent earthquakes. The size of the circle represents the earthquake magnitude while the color represents its depth within the earth. At the end of the animation it will first show all quakes in this 15-year period. Next, it will show only those earthquakes greater than magnitude 6.5, the smallest earthquake size known to make a tsunami. Finally it will only show those earthquakes with magnitudes of magnitude 8.0 or larger, the “great” earthquakes most likely to pose a tsunami threat when they occur under the ocean or near a coastline and when they are shallow within the earth (less than 100 km or 60 mi. deep).

 

Odyssey to the Anthropocene

I came across a good posting on Carbon Brief that gives a succinct historical background for designating the new geological epoch, the Anthropocene, and thought I’d pass it on. As defined by the English Oxford Living Dictionaries, the Anthropocene is:

Relating to or denoting the current geological age, viewed as the period during which human activity has been the dominant influence on climate and the environment.

The Anthropocene is not a formal geologic time unit yet within the geologic time scale – that label will take awhile. But the Working Group on the Anthropocene (a part of the Subcommission on Quaternary Stratigraphy) gave their recommendation to formalize this time unit  to the 35th International Geological Congress in Cape Town, South Africa on August 29, 2016, so there is some progress. The working group suggested that there are options for marking the beginning of the epoch, such as c. 1800 CE, around the beginning of the Industrial Revolution in Europe or about 1950, where the boundary

…was likely to be defined by the radioactive elements dispersed across the planet by nuclear bomb tests, although an array of other signals, including plastic pollution, soot from power stations, concrete, and even the bones left by the global proliferation of the domestic chicken were now under consideration.  From The Guardian, 8/29/2016.

Anyways, it’s worth reading the posting on Carbon Brief by Sophie Yeo about the Anthropocene, and I’ve included one of the posting’s infographics below to peak a reader’s interest.

Infographic: The Anthropocene. By Rosamund Pearce for Carbon Brief.
Infographic: The Anthropocene. By Rosamund Pearce for Carbon Brief.

Tertiary Paleovalleys in the Laramie Mountains, Wyoming

The Laramie Mountains are part of the central Rocky Mountains in southeastern Wyoming. Archean and Proterozoic rocks form the bulk of the mountain range due to late Cretaceous–early Eocene (Laramide) basement-involved uplift. Hogbacks made of Paleozoic to Mesozoic age rocks flank much of the

The Laramie Mountains of southeastern Wyoming contain Proterozoic and Archean rocks that are now exposed by a late Cretaceous –early Eocene (Laramide) basement-involved uplift.
The Laramie Mountains of southeastern Wyoming contain Proterozoic and Archean rocks that are now exposed by a late Cretaceous–early Eocene (Laramide) basement-involved uplift. The Precambrian rocks are flanked by hogbacks of Paleozoic to Mesozoic age rocks as seen in the above photo.

Precambrian cored mountain areas. But what sets the Laramie Mountains apart from the adjoining Colorado Front Range and even the western Great Plains is that upper Eocene to Miocene strata are preserved within the Laramie Mountains and on its sides as paleovalley fill. The reasons for this unusual paleovalley fill preservation can probably be tied to the Laramie Mountains being much lower in elevation than the adjoining Colorado Front Range and that they were not glaciated during the Pleistocene.

I went on a field trip a few days ago specifically to look at the Laramie Mountains Tertiary paleovalleys. It was a really good trip. Emmett Evanoff led the trip and because he’s spent so much time working in the area, he had much info and insight on the paleovalleys. What follows are a few photos from the trip:

High Plains escarpment of Tertiary rocks on the eastern flank of the Laramie Mountains near Chugwater Creek. Eocene White River mudstone and siltstone, beds are capped by coarse sandstone beds. An overlying gravelly sandstone unit, probably of the upper Oligocene Arikaree Formation lies above the White River beds. The Miocene Ogallala Formation of stacked conglomerate sheets caps the entire section.
High Plains escarpment of Tertiary rocks on the eastern flank of the Laramie Mountains near Chugwater Creek. Eocene White River mudstone and siltstone beds are capped by coarse sandstone beds. An overlying gravelly sandstone unit, probably of the upper Oligocene Arikaree Formation lies above the White River beds. The Miocene Ogallala Formation containing stacked conglomerate sheets caps the entire section.
The walls to the Tertiary paleovalleys near Chugwater Creek are hogbacks of overturned rocks ranging from Pennsylvanian to Cretaceous in age.
The walls to the Tertiary paleovalleys near Chugwater Creek are hogbacks of overturned rocks ranging in age from Pennsylvanian to Cretaceous.
Daemonelix burrow in Arikareean strata. The burrow is a corkscrew shaped burrow made by the ground beaver Palaeocastor.
We found a Daemonelix burrow in Arikareean strata. The burrow is corkscrew shaped and was probably made by the ground beaver Palaeocastor.
foodtruck
Pat’s food truck was a welcome sight during the field trip. As she said – good food and good rocks – what’s better than that?

 

Large boulders occur at the base of White River Formation in the Toltec Tertiary paleovalley. The Toltec paleovalley is on the west side of the Laramie Mountains where basal Tertiary strata are exposed at and close to the range margins.
Large boulders occur at the base of the White River Formation in the Toltec Tertiary paleovalley. The Toltec paleovalley is on the west side of the Laramie Mountains where basal Tertiary strata are exposed at and close to the range margins.
Polished boulders of Precambrian granite are found in the Garrett paleovalley which now lies in the drainage area of the North Laramie River. Wyoming is known for wind and these boulders certainly attest to that.
Polished boulders of Precambrian granite are found in the Garrett paleovalley which now lies in the drainage area of the North Laramie River. Wyoming is well known for wind and these boulders certainly attest to that.

 

 

 

The Field Season Is Going Strong in Southwestern Montana

My field season is in full swing. I recently spent time with students from the Webb Schools in Claremont, CA, during their annual sojourn to southwestern Montana. We prospected a few Tertiary localities, with the students making some good fossil mammal and fossil invertebrate finds. We were also extremely lucky to have a southwest Montana landowner give us a tour of a buffalo jump that is on his land. The following photos are from our various fossil site and buffalo jump field adventures.

woodin-snails
Tertiary fossil snails (about 25 My in age) at one locality captured the interest of students. Once one snail was found, everyone was intent on finding more.
Bob Haseman talks about a buffalo jump in the Toston Valley. He is standing by one of the many tepee rings associated with the jump site.
Bob Haseman talks about a buffalo jump in the Toston Valley of southwestern Montana. He is standing by one of the many tepee rings associated with the jump site. The small boulders on the surface between Bob and the students are part of a tepee ring.
Webb School students hiking up to the "Looking-Out" site associated with the buffalo jump. A eagle catchment area is immediately below the highest point of the "Looking-Out" site.
Webb School students hiked up to the “Looking-Out” site associated with the buffalo jump. A eagle catchment area is immediately below the highest point of the “Looking-Out” site.
eagle-catchment
The eagle catchment area is a shallow depression where a person would hide beneath brush awaiting the approach of an eagle. A nearby animal carcass would aid the quest to capture a eagle which was then used for its feathers.
Chadronian (about 36 Ma) age rocks yielded a few brontothere teeth and bone fragments.
Chadronian (about 36 My in age) rocks near Three Forks, Montana yielded a few brontothere teeth and bone fragments for the curious students.
Chadronian strata in this area contain brown to reddish, popcorn textured floodplain deposits and whitish-colored fine-sand channel deposits.
Chadronian strata in this area consist of brown to reddish popcorn-textured floodplain deposits that contain paleosols and whitish-colored fine-sand channel deposits.

 

 

The Yellowstone Volcanics

Caldera boundaries of Yellowstone area eruptions over the past 2.1 million years (U.S. Geological Survey - http://pubs.usgs.gov/fs/2005/3024/)
Caldera boundaries of Yellowstone area eruptions over the past 2.1 million years (U.S. Geological Survey – http://pubs.usgs.gov/fs/2005/3024/)

Volcanic stratigraphy is hard to ignore when touring through the Teton to Yellowstone National Parks (YNP) area. Three major volcanic eruption cycles occurred during the last 2.1 million years and resulted in hundreds of feet of volcanic rock. The eruption cycles make a good basis for separating the volcanic rock units and consequently there are three major volcanic stratigraphic units. These major units consist of ash-flow tuffs that erupted at the peak of each cycle and include the Huckleberry Ridge Tuff with an age of 2.1 million years, the Mesa Falls Tuff with an age of 1.3 million years, and the Lava Creek Tuff with an age of 0.64 million years.

The type section of the Huckleberry Ridge Tuff is at the head of a landslide scarp on the Flagg Ranch, about 2 miles northeast of a bridge across the Snake River.
The type section of the Huckleberry Ridge Tuff is at the head of a landslide scarp on the Flagg Ranch, about 1 mile northeast of a bridge across the Snake River.

The type sections of the Huckleberry Ridge Tuff and the Mesa Falls Tuff are fairly accessible. The Huckleberry Ridge Tuff type section sits at the head of a large landslide about 1.5 miles south of the YNP’s south gate and 1 mile northeast of the Snake River Bridge. It’s a big landslide, so it’s easy to spot from the highway. The type section mainly contains welded rhyolitic ash-flow tuff. This huge eruptive event (one of the five largest individual volcanic eruptions worldwide) associated with the Huckleberry Ridge Tuff formed a caldera more than 60 miles across.

The type section of the Mesa Falls Tuff is a road cut along Highway 20, about 3 miles north of Ashton, Idaho.
The type section of the Mesa Falls Tuff is a road cut along Highway 20, about 3 miles north of Ashton, Idaho.

The Mesa Falls Tuff type section is really accessible as it is alongside Highway 20, about 3 miles north of Ashton, Idaho. The type section consists of airfall tuff, partially welded tuff that has an agglomeratic base. The eruption associated with the Mesa Falls Tuff formed the Henrys Fork Caldera which is in the Island Park area west of YNP.

A more detailed view of the Mesa Falls Tuff with its airfall ash overlain by partially welded rhyolitic tuff that has an agglomeratic base.
A more detailed view of the Mesa Falls Tuff with its airfall ash overlain by partially welded rhyolitic tuff that has an agglomeratic base.
Roaring Mountain lies within the Lava Falls Tuff area (photo from NPS/Peaco - https://www.nps.gov/yell/planyourvisit/norrisplan.htm).
Roaring Mountain lies within the Lava Creek Tuff outcropping area in YNP (photo from NPS/Peaco – https://www.nps.gov/yell/planyourvisit/norrisplan.htm).

The Lava Creek Tuff type section is much more difficult to access as its type section in the upper canyon of Lava Creek, about 8 miles into the backcountry of YNP. There are a couple reference sections that are easier to reach, and one is in Sheepeater’s Canyon, about 0.5 miles northeast of Osprey Falls. The Lava Creek Tuff is also readily seen in the south-facing cliffs along much of the Gibbon River. The eruption associated with the Lava Creek Tuff created the Yellowstone Caldera, the 35-mile-wide, 50-mile-long volcanic depression that dominates the present YNP landscape.

There are many more volcanic units associated with the three major eruptive cycles. But spending time looking at the major ash-flow tuff units is a good way to begin to delve into Yellowstone geology.

North Carolina Sandhills and Weymouth Woods

A pine needle-sand trail in the Sandhills at Weymouth Woods Sandhills Nature Preserve in Southern Pines, North Carolina.
A pine needle-sand trail in the Sandhills at Weymouth Woods Sandhills Nature Preserve in Southern Pines, North Carolina.

My first trek into the Carolina Sandhills began with a visit a couple days ago to Weymouth Woods Sandhills Nature Preserve in Southern Pines, North Carolina. Weymouth Woods is a great place not only to hike through part of the Sandhills, but to also see the longleaf pine forest that readily grows on the sands. The land for the preserve was donated to the North Carolina Division of Parks and Recreation in 1963 by Mrs. James Boyd. Her father bought the land in 1903 so that a part of the region’s original longleaf pine forest would survive. In fact, there are old-growth 400 to 500 year-old longleaf pines still flourishing near the Weymouth Center.

Pileated woodpeckers are a common sight on hikes through the Weymouth Woods Sandhills Naure Preserve. The woods are also home the endangered species of the red-cockaded woodpecker. This woodpecker (which I did see while I was there!) is an indicator species for the overall health of the longleaf pine ecosystem.
Pileated woodpeckers are a common sight on hikes through the Weymouth Woods Sandhills Nature Preserve. The woods are also home to the red-cockaded woodpecker – an endangered species that is an indicator species for the overall health of the longleaf pine ecosystem. This pileated woodpecker was at the feeders in back of the visitor center. I did see 2 red-cockaded woodpeckers at the same feeders, but, unfortunately, I didn’t get any photos of them.

Back to Sandhills geology – the Sandhills are a Quaternary aeolian blanket of sands and dunes that cover part of the Coastal Plain of the Carolinas. That the sands exist in the Coastal Plains uplands of the Carolinas has been known for some time, but recently Moore and Brooks used LIDAR data to show an extensive Upper and Middle Coastal Plain upland aeolian landscape. Moore and Brooks describe their findings as:

“Although primarily an Upper Coastal Plain/Sandhills phenomena, these large-scale eolian features are also present in parts of the dissected uplands in the Middle Coastal Plain immediately east of the Orangeburg Scarp in South Carolina and in the Middle Coastal Plain portions of North Carolina. While the timing is likely related to riverine source-bordering eolian dunes, the sand source for many of these upland eolian deposits appears to be derived from upland incisement and erosion by primarily 1st order streams. In fact, many sources appear to originate from the incised borders of broad dissected coastal uplands with numerous small feeder streams and streamhead sources. In other words, the downcutting and incisement events appear correlated with dune and eolian sand-sheet formation in the uplands where extensive erosion would have provided a plentiful sand source for remobilization as eolian dunes. Although the timing of upland incisement is not clear, it likely occurred most recently during or sometime just after the last glacial maximum when large river systems in the Southeast were transitioning from braided to meandering and incised fluvial systems.”

In the Southern Pines area, these aeolian deposits that comprise the Sandhills are a part of the Upper Coastal Plain Pinehurst Formation, as redefined by Bartlett (1967) in the North Carolina Sandhills.
In the Southern Pines area, the aeolian deposits that comprise the Sandhills are a part of the Upper Coastal Plain Pinehurst Formation as redefined by Bartlett (1967: Geology of the Southern Pines Quadrangle, North Carolina, [M.S. thesis]: Chapel Hill, University of North Carolina, 101 p).
This is defintely different geology from the Montana Cenozoic continental basins than I’m used to. So it was a great change and fun geology to think about. And – if a hike through Sandhills country is on your list, a visit to Weymouth Woods is in order. I used the trails at both the main Weymouth Woods acreage that are by the visitor’s center and also hiked the Paint Hill trails that are also on State Park lands. The Paint Hill trails are a part of the Weymouth Woods Sandhills Nature Preserve, but are located about a mile southwest of the main woods. Both areas are amazing!