All posts by inquisitiverockhopper

Heard Island Landslide!

Landslide on Compton Glacier, Heard Island, 2017-07-21.  Image credit: processed by Bill Mitchell (CC-BY), using USGS/Landsat 8 data.
Landslide on Compton Glacier, Heard Island, 2017-07-21. Image credit: processed by Bill Mitchell (CC-BY), using USGS/Landsat 8 data.

On July 21, 2017, the Landsat 8 satellite imaged a fresh landslide on Heard Island, seen in the picture above. The slide occurred in the northeast portion of the island, on top of Compton Glacier, and I have annotated it for clarity in the image below.

Satellite image of Heard Island with annotation marking the region where the landslide is present.  Image credit: processing and annotation by Bill Mitchell (CC-BY), data from USGS/Landsat 8.
Satellite image of Heard Island with annotation marking the region where the landslide is present. Image credit: processing and annotation by Bill Mitchell (CC-BY), data from USGS/Landsat 8.

This landslide is quite easy to spot because of the relatively clear conditions over Heard Island and the very high contrast between the dark, presumably-basaltic rocks and the white snow of the glaciers. Given that it is presently austral winter and Heard Island is located south of the Antarctic Convergence, the rate of snow accumulation should be quite high. It will be interesting to see how long it takes to be covered by snow.

I am fairly convinced that this is a rock- or landslide rather than an eruption. The head of the flow is along the top of a steep ridge, and the infrared imagery shows no thermal anomaly in this part of the island.

What’s interesting to me is that this slide appears to have eroded some snow on top of the glacier which then caused a secondary avalanche from a north-facing slope. I’ve annotated this in the image below.

Region of secondary avalanche.  Image processing and annotation: Bill Mitchell (CC-BY), data from USGS/Landsat 8.
Region of secondary avalanche. Image processing and annotation: Bill Mitchell (CC-BY), data from USGS/Landsat 8.

This landslide has a run-out of about 2.5 km, an elevation drop of ~750 m, and a total affected area of ~0.8 km2. Several flow tongues are evident in the close-up image, even though the satellite imagery resolution is a modest 15 m/pixel.

Close-up of landslide on Compton Glacier, Heard Island.  Several flow paths of dark rock are evident here.  Image processing: Bill Mitchell (CC-BY), data from USGS/Landsat 8.
Close-up of landslide on Compton Glacier, Heard Island. Several flow paths of dark rock are evident here. Image processing: Bill Mitchell (CC-BY), data from USGS/Landsat 8.

From this image, it looks like the rockfall mostly happened in the portion running west-to-east, then as it turned the corner to head northeast, transitioned to a surface flow. In many ways, this reminds me of the Mt. Dixon (New Zealand) rock avalanche in 2013 (coverage by Dave Petley here and here, among others). The video below is from the Mt. Dixon (NZ) rock avalanche, but is likely similar to what occurred on Heard Island.

A fly-over after the Mt. Dixon (NZ) rock avalanche provided more video of the rock avalanche scar.

I look forward to seeing more images of this slide as they come in. Heard Island is imaged roughly every 8 days by Landsat 8, which as far as I can tell is the only publicly available high-resolution imagery for the island now that EO-1 has been decommissioned.

Capitol Rock Close-Up

Close-up outcrop photograph of Capitol Rock, viewed from the north-northeast.  Image credit: Bill Mitchell (CC-BY).
Close-up outcrop photograph of Capitol Rock, viewed from the north-northeast. Image credit: Bill Mitchell (CC-BY).

Two years ago, I came tantalizingly close to Capitol Rock, an outcrop in southeastern Montana (45.572189, -104.087964) just a few miles over the border from Camp Crook, SD. Unfortunately, I did not have an opportunity at that time to explore the outcrop from any closer than about a quarter mile, but I did find the Ekalaka Quadrangle 30’x60′ (pdf) geologic map.

Recently, I was out in the area again, and this time made sure to have time to take some pictures and see some of what was to be seen. Let’s start with the quarter-mile view, which is roughly equivalent to what I saw last year.

Wide view of Capitol Rock from the east.  Image credit: Bill Mitchell (CC-BY).
Wide view of Capitol Rock from the east. Image credit: Bill Mitchell (CC-BY).

Capitol Rock has three major parts to it: an easily eroded base, a laminated sandstone middle, and a massive sandstone top. A handy turn-out from the forest service road leads right to the base of the outcrop.

The easily eroded base is made of fine, chalky, white sediment sediment, and it remains in horizontal orientation. In several places, this unit is at least superficially porous. Surprisingly, there are occasional chert clasts in the otherwise fine sediments—I’m not quite sure how those would have been deposited or formed here.

Basal unit of Capitol Rock.  Foot for scale.  Image credit: Bill Mitchell (CC-BY).
Basal unit of Capitol Rock. Foot for scale. Image credit: Bill Mitchell (CC-BY).
Cherty clast in the basal sediments at Capitol Rock.  Foot for scale.  Image credit: Bill Mitchell (CC-BY).
Chert clast embedded in the basal sediments at Capitol Rock. Foot for scale. Image credit: Bill Mitchell (CC-BY).

Above the basal unit is a somewhat more resistant, coarser-grained set of beds. These strata are finely bedded, and have a tendency toward spheroidal weathering. Occasionally interbedded with the spheroidal beds are 1–3 cm thick, well-cemented strata of a white or pink color [discoloration?].

Spheroidal weathering of finely-laminated strata.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Spheroidal weathering of finely-laminated strata. Hand for scale. Image credit: Bill Mitchell (CC-BY).
Laminations in the unit displaying spheroidal weathering.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Laminations in the unit displaying spheroidal weathering. Hand for scale. Image credit: Bill Mitchell (CC-BY).
Non-spheroidal bed 1–3 cm thick and slightly orange-pink in coloration, within the spheroidal beds at Capitol Rock.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Non-spheroidal bed 1–3 cm thick and slightly orange-pink in coloration, within the spheroidal beds at Capitol Rock. Hand for scale. Image credit: Bill Mitchell (CC-BY).

The spheroidally-weathered unit also seems to have one or more channels within it.

Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below).  Possible channel cut at right.  Outcrop height in image is ~10 m.  Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below). Possible channel cut at right. Outcrop height in image is ~10 m. Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below).  Possible channel cut at right has been annotated.  Outcrop height in image is ~10 m.  Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below). Possible channel cut at right has been annotated. Outcrop height in image is ~10 m. Image credit: Bill Mitchell (CC-BY).

The upper unit at Capitol Rock has more massive sandstone (see wide view above). I didn’t notice many channels in this unit, although I didn’t get very close. A butte just to the north of Capitol Rock provided a good photograph (below).

Massive unit of Capitol Rock, seen in the butte immediately to the north of Capitol Rock.  Cliff is ~30–40 m tall.  Image credit: Bill Mitchell (CC-BY).
Massive unit of Capitol Rock, seen in the butte immediately to the north of Capitol Rock. Cliff is ~30–40 m tall. Image credit: Bill Mitchell (CC-BY).

Although I have those observations, I don’t have much for interpretation of them. The depositional environment seems to be relatively low-energy (give or take the chert clasts), evidenced by the flat strata, fine grain sizes, and relatively few cross-beds. Changes in the rock types would suggest changes in the sediment sources or the depositional environment (or both). There may be post-deposition alteration effects as well, such as cementation of the spheroidally-weathering strata.

View SSE from the butte just north of Capitol Rock.  Truck for scale in pull-out near Capitol Rock.  Image credit: Bill Mitchell (CC-BY).
View SSE from the butte just north of Capitol Rock. Truck for scale in pull-out near Capitol Rock. Image credit: Bill Mitchell (CC-BY).

Capitol Rock is an interesting outcrop, and if you’re in the area, I’d recommend a stop. The rocks are interesting, there are US Forest Service campgrounds nearby, and the view is quite nice. These units can probably be correlated to the Slim Buttes in South Dakota (~45 miles east).

Lessons Learned at the Regional Science Fair

A young scientist presents in the undergraduate poster session of the American Chemical Society spring meeting, 2007.  Image credit: Ellen Valkevich.
A young scientist presents in the undergraduate poster session of the American Chemical Society spring meeting, 2007. Image credit: Ellen Valkevich.

This spring I had the privilege of being a judge at my local science fair. As a high school student, I had participated in the science fair and it was a huge part of my science learning experience. Now that I am qualified to be a judge, it is time for me to give back while avoiding the trap of turning into the dreaded Reviewer #2.*

I scored quite a few different projects, primarily in Earth & Environmental Science. I was pleased to see the large number of students involved in the discipline, and the interest they showed in environmental monitoring and sustainability. However, I was surprised to see the number of projects which focused on pH, but without understanding of pH of rainwater or the influence of carbonates.

Limited or non-existent access to instrumentation was clearly a limiting factor in many of the projects. That observation leads to a question: what can be done to address the disparity in instrument access and to improve the quality of data being used in science fair projects? I believe the long-term answer to that question is to fund our schools and support the teachers and staff who work in them.

Another solution would be to have students use and analyze publicly available data. In many cases, this cut out some of the hands-on portion of making measurements, which detracts from the overall learning goals. Using publicly-available data also means that teachers would need to be more aware of good data resources and ideas for how to go about analyzing that data—each significantly increasing the work load and responsibilities of the teachers. For research projects, it is important to have a low student:teacher ratio, so that the students can have the support they need to succeed in their project. However, publicly available data allow students to do cutting-edge research with the same tools and data used by professional scientists.

Here are a few examples of low-budget, high-quality data projects that could be interesting:

  • Weather forecast accuracy. Make a daily record of the National Weather Service forecast (for each day forecast) for your area, as well as the almanac data from the closest instrumented NWS station (often an airport). How does forecast accuracy change over time? How accurate is a forecast 72 hours out?
  • Earth-Observing Satellite data. With a constellation of Earth-observing satellites including Aqua, Terra, Landsat (7 and 8), and formerly EO-1, there are mountains of data waiting to be analyzed. Students can look at crop health locally, at glacial changes, deforestation, volcanic activity, wildfires, and a host of other things. Data are freely available, GIS software is freely available, and the data analysis skills are quite relevant in today’s job market.
  • Buoy data. As I’ve mentioned here before, there are several fleets of marine buoys which take various oceanographic measurements, such as conductivity-temperature-depth profiles and current measurements. Oceanography isn’t my thing, but I’m sure there are enough papers that use these data that some project ideas could be found. These projects are likely to use GIS.

* Reviewer #2 is known for being overly critical, wanting a paper that isn’t particularly close to the paper that was submitted, having unreasonable or unattainable expectations, and generally being a jerk.

The Fantastic Beauty of Heard Island

The Beauty of Heard Island.  Image credit: Bill Mitchell (CC-BY)
The Beauty of Heard Island. Image credit: Bill Mitchell (CC-BY)

Heard Island is a place of fantastic beauty. Yes, the weather can be bleak and windy, but that too gives Heard Island some of its unique character. One morning I stepped out of the tent around sunrise, and was greeted by the scene above. I stood in awe for a moment at the landscape, which looked as though it were straight out of a painting. Things change quickly on Heard Island, so after only the moment’s pause, I ran back into the tent for my camera, and managed to take a few pictures that came out looking exactly like what I saw.

Glacial ice on the beach at Corinthian Bay, Heard Island.  Image credit: Bill Mitchell (CC-BY).
Glacial ice on the beach at Corinthian Bay, Heard Island. Image credit: Bill Mitchell (CC-BY).

Scenery on Heard Island was usually dramatic, with gloomy greys punctuated with bursts of color—often the orange patches of king penguins. The wide, featureless nullarbor added to the fantastic feeling of the island by removing any sense of scale one might have.

King penguins standing on the beach watching the surf, Corinthian Bay, Heard Island.  Image credit: Bill Mitchell (CC-BY).
King penguins standing on the beach watching the surf, Corinthian Bay, Heard Island. Image credit: Bill Mitchell (CC-BY).

For more pictures from Heard Island and the voyage on the Braveheart, please see the Flickr album.

Nares Glacier to Mount Drygalski Panorama

Panorama from Nares Glacier (left) to Mt. Drygalski (right) from the Atlas Cove camp.  This view spans from ESE through SSW, and is roughly 85 megapixels at full size.  Image credit: Bill Mitchell (CC-BY, hosted on flickr).
Panorama from Nares Glacier (left) to Mt. Drygalski (right) from the Atlas Cove camp. This view spans from ESE through SSW, and is roughly 85 megapixels at full size (28 MB). Image credit: Bill Mitchell (CC-BY, hosted on flickr).

One year ago, I was on Heard Island. Over the course of the expedition I took more than 6000 photos. Although I took three images with the Gigapan (Big Ben, the Azorella Peninsula, and—my favorite—Windy City), I also took photos for stitching together manually using my own camera.

I have been slow in stitching these pictures together, but with the one-year anniversary of their production coming around, I decided it was time to finish one or two of them. This is the first, and I hope I’ll find time to finish more. Putting it together, I was amazed that this is still a relatively wide-angle compared to what I had available: 70 mm on a 70–200 mm lens. The detail came out well, as is evident at full-size. The glaciers, moraines, and hills are all more than a kilometer distant over the “nullarbor”, a broad, flat, volcanic-sand plain.

Toward the left half of the image are some penguins for scale. They look like king penguins, putting their height around 1 meter. I count at least 31 penguins in the entire image.

I think I spot some of the relatively rare basement limestones cropping out at the very left edge of the image, and their appearance is consistent with a dip of 25–35° to the south.[1] A closer view (200 mm focal length) shows them more clearly.

Location of limestone, with annotation.  Image credit: Bill Mitchell (CC-BY).
Location of limestone, with annotation. Image credit: Bill Mitchell (CC-BY).
Full-zoom on the limestone outcrop.  Bedding is clearly visible, dipping south.  Image credit: Bill Mitchell (CC-BY).
Full-zoom on the limestone outcrop. Bedding is clearly visible, dipping south. Image credit: Bill Mitchell (CC-BY).

[1] Quilty, P. G. & Wheller, G. 2000; Heard Island and The McDonald Islands: a Window into the Kerguelen Plateau. Papers and Proceedings of the Royal Society of Tasmania. 133 (2), 1–12.

Where on Google Earth #598

In WOGE 597, Stephanie showed us active sand dunes on the eastern shore of Lake Michigan.

Now we leave the glacial plains behind and head for the hills.

WOGE 598

Find the location, and leave a comment describing the important geology/hydrology/etc. of the scene. The person to leave the first correct location/comment gets to host the next WOGE.

Complete rules, hints, and a kmz file of previous locations can be found on Felix’s blog.

Where on Google Earth #597

In WOGE 596, we headed up the Nile River to the Aswan Dam.

Now, in a guest post, first-time winner Stephanie Januchowski-Hartley (@ConnectedWaters) takes us here:

Where On Google Earth 597

Find the location, and leave a comment describing the important geology/hydrology/etc. of the scene. The person to leave the first correct location/comment gets to host the next WOGE.

Complete rules, hints, and a kmz file of previous locations can be found on Felix’s blog.

Good hunting, and thanks, Stephanie, for the new image!