Clastic Detritus

Mud flow caught on video

Brian Romans — Thu, 02 Sep 2010 14:00:08 +0000

This video has already made the rounds the last couple days (e.g., Geofroth and Geotripper) but I couldn’t resist posting it here. The large truck offers both scale and an illustration of the power of moving mud.

As far as I know the video was first posted here.

Filed under: video

Writing in the geoblogosphere (week of August 23-29, 2010)

Brian Romans — Mon, 30 Aug 2010 12:00:33 +0000

This week-in-review idea continues to evolve so bear with me. To help focus what I put in this weekly digest I’m going to highlight posts that include some interesting writing. I’m also going to limit myself to five:

Check out this epic post from one of Callan Bentley’s students on Mountain Beltway to learn about the geology of Glacier National Park in Montana.
Chris Rowan from Highly Allochthonous discusses a new paper documenting the fascinating interaction of a subducting slab with a continental hot-spot mantle plume.
Michael Welland from Through the Sandglass writes about the ephemerality of islands made of shifting sand and the challenges of making maps of such transient features.
Jessica Ball from Magma Cum Laude posts about her trip to the island of Montserrat and Soufriere Hills volcano, providing some nice background on the geology.
Speaking of volcanoes, Garry Hayes from Geotripper discusses kipukas (islands of land surrounded by young lava flows) in Hawai’i and how they can become unique collections of various plants and animals.

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List of most recent week-in-review posts: http://clasticdetritus.com/category/week-in-review/

Filed under: week-in-review

Sea-Floor Sunday #72: Indus submarine canyon

Brian Romans — Sun, 29 Aug 2010 15:00:38 +0000

The ongoing flooding of the Indus River in Pakistan inspired me to search for an image of the Indus submarine canyon for this week’s Sea-Floor Sunday image. The image below is from this website describing a research cruise in 2008-2009 that acquired multibeam bathymetry data and cores. Check out the site for more details about the study.

The purple colors are deeper water and nicely show the sinuous canyon. The canyon is between 1 and 2 km wide and up to 1,100 m (~3,600 ft) deep. The tight meander bends remind me of this place. This submarine canyon feeds the enormous Indus submarine fan, which is 1500 km (900 mi) long and 960 km (575 mi) wide, second only to the Bengal submarine fan in size.

Bathymetry of Indus submarine canyon (credit: http://www.abdn.ac.uk/~wpg008/PelagiaIndusCruise.html)

Here’s a zoomed-out map from Google Earth for context.

Filed under: map, marine science, rivers, sea-floor image, Sea-Floor Sunday, sedimentary basins, turbidites

Friday Field Foto #122: Channelized Miocene strata, Tierra del Fuego

Brian Romans — Fri, 27 Aug 2010 15:00:06 +0000

This week’s Friday Field Foto is from some Miocene beach-cliff exposures on the Atlantic coast of Tierra del Fuego. These sandstones are characterized by a mix of ‘normal’ turbidites thick successions of traction-dominated (including large climbing dunes) deposits. Also note the surface cutting down from left to right in upper part of cliff — a nice erosional surface, which is overlain by mostly thin-bedded, fine-grained strata.

Happy Friday!

Filed under: Friday Field Foto, Patagonia, photographs I've taken, sedimentary structures, sedimentation, turbidites

Getting back into the swing of things

Brian Romans — Wed, 25 Aug 2010 16:55:33 +0000

Just a quick note for today. My lack of posting lately is the result of numerous interacting factors converging all at once. I apologize for not getting my weekly round-up of (what I think is) interesting writing in the geoscience blogosphere out this Monday. The entire staff here at Clastic Detritus came down with a nasty head cold and could only maintain enough mental focus to watch movies. The global-disaster-by-catastrophic-plate-tectonics film ’2012′ was quite enjoyable while in this intellectually challenged state.

I’ve got a few posts in the hopper that will be done in the coming days. In the meantime, check out this video posted on Dave’s Landslide Blog this morning of a debris flow in Pakistan (and wait until about 1 min 15 sec into the video for the interesting part). Wow.

Filed under: metablogging, personal, video

Sea-Floor Sunday #71: Live feed from active submarine volcano

Brian Romans — Sun, 22 Aug 2010 17:17:46 +0000

This week’s Sea-Floor Sunday image is from a site I saw linked to by various folks the past week. As part of NSF’s Ocean Observatories Initiative they have included a live feed from Axial Volcano, an active volcano along the Juan de Fuca ridge offshore of Oregon. This is a great idea and, similar to video feeds for volcanoes on land, observatories like this will be important for capturing submarine volcanic activity. Check out the daily log of this research cruise.

Clicking on the image below will take you to the page with the live feed.

Static image of this live feed: http://interactiveoceans.washington.edu/story/Live+Video

Here’s a map of the location of Axial Volcano and check out this page to learn more.

General plate tectonic map of the NE Pacific Ocean showing the North American, Pacific, Explorer, Juan de Fuca, and Gorda plates. The Coaxial Segment is just N of Axial Volcano along the Juan de Fuca Ridge. (credit: http://www.volcano.si.edu/world/vol_extra.cfm?name=Blanco%20Transform%20Fault%20Zone)

Filed under: igneous rocks, map, marine science, photos/images, plate tectonics, sea-floor image, Sea-Floor Sunday, video

Geoblogosphere week in review (August 9-15, 2010)

Brian Romans — Mon, 16 Aug 2010 21:29:11 +0000

Here are several posts from the geoscience blogosphere last week highlighting interesting writing:

Michael Welland of Through the Sandglass discusses all the sand-related activities one can enjoy while visiting the Exploratorium in San Francisco.
David Bressan of History of Geology digs into Lyell’s and others work from the 1800s with a post about the concept of cycles in geology.
Garry Hayes from Geotripper posts an update on the whole removal-of-serpentinite-as-California’s-state-rock affair. Also make sure to see Silver Fox’s (from Looking for Detachment) constantly updated list of blog/media coverage of the issue.
Rachael from 4.5 Billion Years of Wonder has a post titled The Great Geological Fart … need I say more to make you want to read it?
Chris Rowan from Highly Allochthonous discusses the scale of an eruption at Yellowstone 600,000 years ago and the vast area across which the volcanic ash was spread. Chris gets double-billing for his nice summary of the recent findings that the Haiti earthquake was not associated with the Enriquillo Fault.
Jim Lehane of The Geology P.A.G.E. is working on a comprehensive series of reviews and discussion of the scientific concepts (uses and abuses) in the disaster movie Armageddon. Check it out.
A Life Long Scholar from The Musings of a Life-Long Scholar writes a clear and succinct post about the differences between contact and regional metamorphism.
Zoltan Sylvester of Hindered Settling writes about the complex patterns and processes of sinuous channels by highlighting two recent papers about modeling efforts of both terrestrial and submarine channels. (By coincidence, my Sea-Floor Sunday post from yesterday also mentioned the comparison of rivers to submarine channels.)

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List of most recent week-in-review posts: http://clasticdetritus.com/category/week-in-review/

Filed under: week-in-review

Sea-Floor Sunday #70: Black Sea submarine channel system

Brian Romans — Sun, 15 Aug 2010 17:00:28 +0000

This week’s Sea-Floor Sunday image* is from the Black Sea side of the Bosphorous Strait and, as always, shows sea floor bathymetry (hot colors are shallower water and cooler colors are deeper water). Note the prominent channel carving its way into deeper water and then possibly splitting into smaller channels. Or maybe those are overspill channels? Pretty awesome I say.

credit: The Daily Mail

I blogged about this channel system in June 2009 and showed a similar, although much less colorful, image in this post.

The image above and the following quote are from this article in The Daily Mail.

The undersea river – the only active one to have been found so far – stems from salty water spilling through the Bosphorus Strait from the Mediterranean into the Black Sea, where the water has a lower salt content. This causes the dense water from the Mediterranean to flow like a river along the sea bed, carving a channel and deep bank.

The second sentence of that statement is a good one — it explains the mechanism for the origin of this submarine channel system (i.e., saline density currents that hug the sea bottom) and mentions it forms a geomorphic feature similar to a terrestrial river. But the first sentence causes my inner nerd to itch a bit. Firstly, submarine channels are not “undersea rivers” — at least, I’ve never heard anyone else who studies these features call them that. The quote from the researcher included in the piece is simply painting a picture for a general reader that the geomorphology is similar to a river. Secondly, what exactly is meant by “the only active one to have been found so far”? If they mean the active submarine channel systems then, no, this is not the only active one — there are numerous submarine canyon-channel systems that have transmitted density currents in recent decades (e.g. Monterey, Var, Hueneme, Congo, etc.). Perhaps they mean the only active system in which a saline current is the dominant agent? I’m not sure about that — maybe some of my readers could comment on that.

Don’t get me wrong, a discussion about what aspects of submarine channels are similar to rivers and what aspects are different from rivers is a discussion very much worth having. In fact, having that discussion helps us understand these features much better. But, I’m not ready to let the mainstream press and the general public simply call these ‘undersea rivers’ and be done with it — there’s still far too much to learn.

* pointed out by @jeffersonite last week

Filed under: rivers, sea-floor image, Sea-Floor Sunday, sediment flux, sedimentation, shallow-marine, turbidites

Friday Field Foto #121: Muddy tidal flat in the Arctic

Brian Romans — Fri, 13 Aug 2010 14:00:53 +0000

This week’s Friday Field Foto is from the Adventdalen River mouth near the town of Longyearbyen, Svalbard.

Check out more photographs from a trip I took to Svalbard in June 2009 on this Flickr page.

Filed under: delta, Friday Field Foto, marine science, photographs I've taken, rivers, sedimentation, Svalbard

Geoblogosphere week in review (August 2-8, 2010)

Brian Romans — Mon, 09 Aug 2010 12:00:43 +0000

Here are several posts from the geoscience blogosphere last week highlighting interesting writing/blogging:

Dave Petley of Dave’s Landslide Blog started covering the Indus River flooding in Pakistan last week with this post discussing the inevitable southward progression of the flood wave and then continued fantastic coverage throughout the week (Aug 3, Aug 4, Aug 5). The latest post from a couple days ago is here.
Erik Klemetti of Eruptions is asking for some feedback about his coverage of the Eyjafjallajökull eruption this past spring — and, wow, as of this writing he had over 180 comments!
Garry Hayes of Geotripper shares some photographs from a former student climbing El Capitan in Yosemite (which takes ten days). Wow!
Mark Wilson of Wooster Geologists shares a quick story of how his presentation at a conference was interrupted by a fire alarm only a minute before the conclusion!
Ole Nielsen of olelog briefly discusses a paper that came out in PNAS about using frogs to address plate tectonics.
Chris Rowan of Highly Allocthonous shares his thoughts on the largely strike-slip movement related to a 4.8 earthquake that occurred in the Grand Teton Mountains of Wyoming this past week.
Speaking of the Tetons, Julia of Stages of Succession highlights reports about Wyoming state officials considering (threatening?) selling a large chunk of Grand Teton National Park.
A new geoscience blog on the scene by Katharine N. called Hydrofelicity has a nice summary of group of groundwater contaminants known as DNAPL (Dense Non-Aqueous Phase Liquids). This is some good background for those wondering what contaminant hydrogeologists deal with.
Ryan of The Martian Chronicles talks about his trip to Glacier National Park to observe and interpret some very old sedimentary rocks — and he ends the post with a doozy of a photo geopuzzle.

In the wake of the most recent Accretionary Wedge, which reflected on the role of geoscience blogs, there were a couple of follow-up posts of note:

Chris Rowan of Highly Allocthonous continued the discussion of geoscience blogging within the context of the announcement and unveiling of a new science blogging collective called Scientopia. The comment thread is especially valuable in that it seems to have sparked an idea to create a group blog about geoscience as it relates to policy and society. We’ll see who steps up and takes the reins on that one.
Ron Schott of Ron Schott’s Geology Home Companion organized the first ‘Current Issues in the Geoblogosphere’ online discussion via Skype this past weekend. Several bloggers participated and they covered a lot of different topics. Check out this fantastic bullet-list summary of the topics discussed and find a link to download and listen to the audio here.

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List of most recent week-in-review posts: http://clasticdetritus.com/category/week-in-review/

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Filed under: week-in-review