Visual Correlation Using Gigapan Imagery

In thinking about how to best apply Gigapan imagery for scientific uses I’ve come up with a couple of ideas. One of the most obvious ones is to take a series of Gigapans of something geological that changes on a daily/weekly/monthly/yearly timescale. Tracking glacial advance and retreat is an obvious application of such an idea. Unfortunately I haven’t got any glaciers in my backyard and I strongly suspect that others are already beginning to work on this (e.g., Briksdal Glacier 2 – Briksdalsbreen).

What I do have in my backyard are lots of flat-lying sedimentary rocks – many deposited on the floor of the Cretaceous Western Interior Seaway. And since I’m already doing a mapping project in Rooks County, Kansas it would be useful if I could find something scientific to do with my shiny new Gigapan unit (besides showing off confusing faults). One idea that has come to mind is the possibility of using the Gigapan images for what I’ll term “visual correlation”. By putting two Gigapan images side-by-side (see below) each image can be manipulated independently to zoom in on some particular feature and then compared to a possibly correlative feature in the second image. Try it yourself…



Side-by-side identical images of a small normal fault. Zoom in on a portion of the stratigraphy in the footwall in the left image and then zoom in on the same strata in the hanging wall on the right image. Adjust centering and zoom as necessary in order to visually correlate the strata from the opposite sides of the fault. More examples can be found here.

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One of the challenges of doing this sort of correlation is finding an appropriate way to add a scale to the images. Up to now I’ve used a tape measure in a couple of Gigapans and the little Mainzelmännchen (Edi and Berti) as a very fun/informal scale. The tape measure is really not ideal since it’s very hard to keep it erect in a stiff (or even slight) Kansas breeze, but it’s what I had handy. I’d much rather have something with metric units, and I’ve contemplated getting a surveyors rod (or two). Another problem is that scale is not constant throughout the panoramas, particularly if you’re showing a wide angle view where things recede into the distance. This presents some real challenges for making quantitative measurements.

I’d really like to get some community feedback on this. Do you think this sort of visual correlation could be useful scientifically? What would make it more useful? Are there better ways to integrate quantitative scale information into a Gigapan? And what other ways do you think the Gigapan imagery could be usefully employed in geology?

Where on (Google) Earth #114?

I’ve been looking for some new and exciting geologic landform to feature here, but it seems that I’m running low on good ideas. So, after solving Peter’s Beautiful Blue Lagoon, I’m going back to a plain old vanilla (or rather, in this case, chocolate) river. Once again, I WON’T invoke the Schott Rule, so basically it’s a free for all.

Basic map view, but watch that Z arrow…

Where on (Google) Earth #114

If you haven’t played before: Identify the location of the feature (latitude and longitude will do) and describe the geology as best you can. We’re pulling for you!

Hmmm…

Part of my ongoing research is a project aimed at some basic bedrock geologic mapping of Rooks County, Kansas. Given that this is western Kansas, deep within the North American Craton, and the rocks exposed in the area are generally flat-lying Cretaceous (Western Interior Seaway) and Tertiary aged sediments, one doesn’t expect to find too much in the way of interesting structural geology. There are some very small offset normal faults that are well exposed in roadcuts – nice for teaching about fault motion, but not particularly earth shaking (not recently, anyhow).

So it came as quite a surprise when my undergrad field assistant and I happened upon the following outcrop:

What you see in the Gigapan above is a view of a small roadcut southwest of Stockton, Kansas. On the left side of the cut you can see massively bedded, bioturbated layers of the Fort Hays Limestone member of the Upper Cretaceous Niobrara Formation in depositional contact above black shales of the Blue Hill Shale member of the Upper Cretaceous Carlile Shale Formation. Both of these units were deposited in the Western Interior Seaway and are found throughout our mapping area. Elsewhere there is another unit, the Codell Sandstone member of the Carlile Shale that is found depositionally between these two, but its thickness is variable and its distribution is not continuous. Most of the exposures of this contact in the area nearest this outcrop lack anything but a hint of sandy shale which might correspond to the Codell Sandstone at the contact, so what you see on the left side of this outcrop is not in any way out of the ordinary.

What makes me go “Hmmm…” is the right side of this roadcut. Clearly there is a fault contact that dips to the east. Slickensides visible on the underside of the Fort Hays limestone along this fault (you can see them if you zoom in) clearly indicate nearly pure dip-slip motion on the fault. What’s baffling is that the unit in the footwall of the fault appears to be Codell Sandstone! This presents a bit of a problem. Since the Codell is usually exposed as a thin layer (not usually of mappable thickness) at the contact of the Blue Hill Shale and Fort Hays Limestone it is perplexing to find a relatively thick exposure of it without any evident top or bottom. The fact that it is generally not even present in this region is part of the issue, but another issue is in trying to explain the sense of offset on the fault. If this is correctly identified as Codell Sandstone (and there are no other sandstone units in the map area that resemble it), then we have a quandary over whether this fault is in fact a normal or reverse fault, not to mention the question of how much offset there is across it. I don’t have a good answer. Any suggestions? Maybe a structural geologist has seen something like this before?

By the way, I had another pair of field assistants with me when I went out to photograph the Gigapan last week. Berti is helping out by holding the tape measure for scale, while Edi is looking on from the footwall region. If you want to make snapshots on this Gigapan and comment on them you can do so at the Gigapan website. If you’re interested in a Gigapan Opportunity for Geoscientists let me know.

Update: This post is part of the geoblog carnival Accretionary Wedge #6. Go visit the Lounge of the Lab Lemming to see what makes other geologists go “Hmmm…”

Where on (Google) Earth #112?

It’s been a while since I won a Where on (Google) Earth challenge. In fact, the WoGE series has really gone global since it’s last visit here, making stops at quite a few new geoblogospherians. Most of those WoGEs haven’t lasted long enough for me to even take a shot since my own personal Schott Rule waiting period is now over 30 hours. Finally, this past weekend I found Fidel Castro’s old stomping grounds before the rejuvinated crowd beat me to it. Apologies for being slow to post a new one – I’m a little rusty.

While I’ve been away from Where on (Google) Earth I’ve enjoyed participating in a couple of other GeoPuzzles that have sprung up in the community. Identifying the mystery impressions from Hawaii earned me a poster (Thanks Tuff Cookie!!!), while in attempting to solve the mystery mineral from South Africa I discovered a geologic misconception of my own. I’ve got to admit, though, that the most fun I had with a geopuzzle was figuring out the identity of the eleventh edition of the Airliner Chronicles.

It was also that last GeoPuzzle that led me to select the location of the current Where on (Google) Earth challenge. Think of it as something of a hybrid WoGE/Airliner Special. Oblique views from Google Earth (top) and Boeing 737-800 (bottom):

Where on (Google) Earth #112
Where on (Google) Earth #112

For the newbies: Identify the location of the feature (latitude and longitude will do) and describe the geology as best you can. We’re pulling for you!

And frankly, I’m sick of the Schott Rule so I’m explicitly NOT invoking it!!! Who was the idiot that thought it up anyhow?

Geoscientist Gigapan Opportunity

If any of you are interested in getting in on a pilot program for geologists to explore scientific applications of Gigapan photography please let me know, as I may be able to get two or three of you involved in the second phase of the program. You’d need to be able to attend a workshop on May 23-24, 2008 in Estes Park, Colorado.


Edi stands in awe of Dinosaur Tracks, Amherst College Geology Museum
Launch Full Screen Viewer