Thursday, October 10, 2013

...on a jet plane.


While Indianapolis has a fair amount of modern suburban sprawl to the north and south, by comparison it shuts off like a switch to the east and west. It's always amazed me how you can be driving west out 56th Street and suddenly you're in corn fields. The above photo is looking down just outside the perimeter highway, I-465.

Click to greatly embiggenate.

Somewhere out over western Kansas or Nebraska, I think. (At any rate, one of those big flat rectangular states that were apparently on sale in the mid-19th Century, so we bought a bunch.) Anyhow, the setting sun is throwing some weird crater-looking geological features into sharp relief down there. Anybody know what those are?

48 comments:

Anonymous said...

"Anybody know what those are?"

Irrigated fields would be my guess

Rob

Joe said...

I believe those shapes are irrigated farm fields that they are pumping water out of the High Plains Aquifer for. They are out in western Kansas and Nebraska.

stevierayv said...

They are circle pivots

Ygolonac said...

Jackalope tracks.

Anonymous said...

looks more where the plains meet the mountains. Not flat enough for Kansas or Nebraska!!!!

Anonymous said...

Have a Safe Trip. Have Fun.

The circles are center pivot irrigation rigs. It's too dry out west for many crops, and this is one way to grow crops like corn and beans. Unlike the "Grapes of Wrath" in the dirty thirties.

Chas Clifton said...

That almost looks like parts of southeastern Colorado. Ask the Farm Family to take you into the Purgatory River canyon next time you are in the neighborhood.

Tam said...

I know what center pivot irrigation fields are. I am referring to the oblong depressions with raised rims that are oriented roughly northwest to southeast.

Anonymous said...

Depending on where you were over Kansas, it may be the Flint Hills.

Antagon said...

I think she is talking about the eye-shaped crater reliefs closer in. I have no idea.

Joel said...

Remnants of the prehistoric nuclear war that wiped the reptilian race off the planet, permitting the rise of mammalians. We don't talk about it, Tam, those bones were put there by God to test our faith.

Keads said...

Maybe a variant of playas? Saw them in Texas and those look about the same.

tailwind said...

Could be rocky areas that were too difficult to plow under and grow things on.

Or, they could be zits.

Kevin said...

I think Joel was the other guy who read The Toolmaker Koan.

Those do look suspiciously like impact craters, don't they?

Anonymous said...

Those are dinosaur backscratchers.

Bram said...

Western Kansas has many beautiful rolling hills.

I assume the circles are those automatic watering systems they put over some crops. I've seen the same green circles while flying over Arizona and Utah.

jetaz said...

My suspicion is that they are deposits from wind erosion. That the dust hit something, and deflected to the side, and that over time, it filled in.

But their direction is consistent with the ridgeline of the hills around them, and they are oriented in the same direction as the erosion gullies south of them; so even if they are not caused by erosion, I suspect that they are part of the natural geological processes of the area.

Also possible is that somebody got bored and decided to take the tops off of mountains, like wings off flies.

Robert said...

You got the same seat I always seem to get. Right side and directly behind the wing.

billf said...

Are you guys serious?
How could any regular readers think that TamSlick,the world traveler,does not know what circular irrigated fields are?
Furthermore,she called them "crater looking geological features".I admit I don't know what they are,but I know one thing they are not.

Critter said...

the earth had a rash at one point. it's better now.

Anonymous said...

Likely impact craters from the stone age impact event that left marks like this all over North America. See:

"The Cycle of Cosmic Catastrophes: How a Stone-Age Comet Changed the Course of World Culture"

Scott J said...

Whenever I flew over scenery like that I always wondered what it might be like to live right where the flat stuff butts up against the wrinkly stuff.

Although I sort of do now but it isn't as noticeable because we have so many more trees than that part of the country.

Hunter said...

I'm thinking that you were further north than you thought. Looks similar to the outlying geography of south-central Idaho. Craters of the Moon country. That is a huge chunk of lava and old craters. Easy to make this a part of that geology.

fast richard said...

It's hard to tell much from a single aerial photo. If they are definitely depressions rather than hills, one possibility would be slumping around sinkholes in a region of limestone caves.

Goober said...

They just look like what we call scab patches here in the palouse. They are areas that can't be plowed because the bedrock is exposed there or there are big donnikers sticking up or, as is often the case around here, its too effin steep.

They get the "eye" shape from how they drive the plow tractor around the obstruction. You cant really turn a plow, so you work your way over, then work your way back once you get past.

The relief is created by the plow, too. Since the areas around them get plowed and they don't, there tends to be a bank or berm building up to them or cutting down to them, as plowing tends to fill in low spots and cut down high spots over the years.

Those are man made features, tam, and they are unfortunately quite mundane. Sorry
..

Rob said...

Flying? Unpossible. With the government shut down, there's no way airlines could continue operating; they would fall from the sky without the benevolence Big Government.

Tam said...

Goober,

Too irregular. More importantly, they're not in the farmed areas.

Darrell said...

A quick google search shows only the Haviland meteor crater in Kansas, said to be about 50 feet across. Kansas has been host to some famous meteorites, though, notably the Brenham pallasites. The Brenham fall and Haviland crater are from the same event, I believe.

Jim said...

The scenery is consistent with much of Dry Flyover from about the 100th Meridian to the Rockies proper. Lower left hills could be Nebraska Sand Hills country. Could also be the Canyonlands of south Kansas. (shrug)

Anyway, it gave me an idea. Next time I have to fly and decide to shoot out a window, I'll also take a shot of the navigation screen most airplane companies hang on the front wall of the cabin. Bingo, my memories are geolocated.

Jeffro said...

The bas relief stuff is just water erosion over centuries - those are little draws and gullies that are in grass now, and used for cattle grazing. Too rough to farm.

When you are driving through some of those areas, you'll think you are in a flat area, then pop over a rise and there is a little shallow hidden valley before you. Then you climb back out (not much of a climb) back on to the high plains.

Some of those little areas have water in the draws, and lots don't. There are generally a lot more trees than compared to the farmed ground. There are also a lot of game trails there as well because of the cover.

Jeffro said...

And then, looking at the middle of the pic you can see some scattered center pivot systems, and there is a little dryland ground around (the rectangles) - the rest of the area isn't being farmed. I'd say that was because the ridge looking dealios are little hills of chalk bluffs or limestone that just don't promote farming. There are several areas that have rock formations rising from the prairie. North of where I live there are two places - Castle Rocks and Monument Rocks that are limestone outcroppings shaped by wind and rain.

Just remember, if you see ground from the air that isn't farmed, it's usually because you can't get a tractor across it.

KM said...

Jim, don't shoot out a window.
It pisses off the waitress and hot brass hits the person next to you.

Roberta X said...

"...the oblong depressions with raised rims that are oriented roughly northwest to southeast."

That's where we've been shelling. Shhh! Don't tell.

Charles Pergiel said...

I thought Nebraska was all farm country, but there are places that have less than one person per square mile.

Will said...

I was thinking they were secondary debris craters, but it seems they still cause circular craters, until the impact angle gets below 5 degrees. I'm thinking that would be unlikely, in an atmosphere like ours.

That big one looks like it has terraces going across the short length.

fast richard said...

If we knew where this was taken, something like Google-earth might offer a better view.

og said...

Where there is a lot of irrigation taking place, you can get sinkholes, and they are likely to happen where the overburden is loose, not where the well is actually drilled. Seeing as those sorta kinda line up with the ravine lower in the photograph, I would have guessed them to be subsidences over an underground aquifer.

Anonymous said...

So, the consensus is that NO, we don't know what it is (they are).

Goober said...

Not anymore, you mean. Not since they brought in the center pivot irrigators and started growing crops they dry land there couldn't handle before.

I stand by my analysis. Those are scab patches. Old ones, from fields that were farmed 50 years ago but are too marginal to be profitable now and are now fallow.

We have the same thing here. My late great uncle has what used to be an old alfalfa field that he stopped cultivating back in the 70s that looks just like your pic.

As for being too irregular, one wonders how the farmer would put bedrock protrusions into order....

Those fields used to be farmed. No longer are. Those features are just the leftovers from that.

Goober said...

Not true. Lots of farmable land that was farmed years ago is no longer being farmed, even though you can easily farm it.

Look up CRP. its a federal program that pays farmers to put marginal land into fallow.

Also, economies change. Marginal land that could be profitable 50years ago is not profitable today so they stopped farming it. It happens all the time. See my great uncles example above

Anonymous said...

Square areas with circles inside of them can only really be center-pivot irrigation; especially spaced so regularly. Stuff grows where the water hits and less so where it doesn't. I've seen these all the time flying in an out of Omaha and Lincoln.

Anonymous said...

Looks like your picture is roughly of here: View Larger Map
Just north of McCook, Nebraska. If the government wasn't shut down, we could go to the USGS site and find out what kind of rock is there.

Dallas

fast richard said...

Bingo, that's the spot. That distinctive pattern of six circles with three more just to the southeast is good for getting oriented.

Some of the depressions are fairly big and have evidence of layered rock around the edges, consistent with possible limestone.

Looks like a complicated sedimentary area with oil .

og said...

If you locate the area on google earth- it's about 40degrees 35 minutes by 100 degrees 51 minutes, and then roll the slider back to the 1993 snapshot, you can see the 'Craters" in sharp relief.

They look like tops of hills that have been removed- but if that's it, it was a long time ago. I think it would be consistent with subsidence, because if humans had removed the material it would not have been so haphazard. One way or another, some are newer and have sharp edges, and some are older, and some have some narly assed looking dirtbike tracks on them

Anonymous said...

They are probably kettles (depressions) or drumlins (elongated hills)--glacial features that are the hadelki results of the last ice age

Anonymous said...

I've heard them called rainwater lakes (southeastern Nebraska) and playas (western NE, KS, TX Panhandle). There's lots of cussin' and discussin' over what makes them - baby sink holes, a combination of wind and water erosion, buffalo digging out wallows, micro impact craters, or yes. Some had live springs in them in the days before widespread groundwater irrigation.

LittleRed1

Tam said...

"Square areas with circles inside of them can only really be center-pivot irrigation; especially spaced so regularly."

We're talking about the terrain features, not the center-pivot irrigation fields, as noted multiple times in earlier comments, but thank you anyway.

deadcenter said...

My first comment vanished for some reason, probably user error.

Best guess in looking at the area in Google Earth is sinkholes and other terrain features common to karst topography or dissolving limestone. Steep sided depressions many filled or containing water, others have what appears to be grey bedrock exposed in them.

The area is too far south and west to be glacial features, at least they are from the geologic maps I've found of the area.