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GeoKitten! Inverted Topography Kitteh

The views expressed are those of the author and are not necessarily those of Scientific American.


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You love kittens, right? Who doesn’t! And kittens are especially hard to resist when they illustrate neat geological concepts.

Kirby and Luna belong to my friend B, and they are killer cute. This is Luna’s first outing as a Geokitten, and Kirby’s first time out as a Geokitteh. Give them an awwww.

Kirby and Luna Inverted Topography

Kirby and Luna demonstrating inverted topography.

 

Here we have older adopted brother Kirby nicely illustrating the concept of inverted topography. See how he forms a well-defined ridgeline there? At some point in the past, Kirby Ridge used to be the valley of the ancestral Kirby River. Then something happened to fill the valley. Lessee… he’s a pretty pale color, so it looks like he’s probably an andesite flow. So some nice, hot andesite that wasn’t gaseous or viscous enough to go splodey erupted from what is now Kirby Mountain (not depicted). It flowed down the valley of the ancestral Kirby River, forcing it into a different channel, and filling the valley right to the tip-top with hot rock, which cooled into a nice, solid mold of the old valley. Lots and lots of time passed, and erosion did its work, but the Kirby andesite flow was made of tougher stuff than the old valley walls and surrounding areas – let’s assume that the river was cutting a valley through softer stuff like tuff, scoria, old lahar deposits, and perhaps some glacial debris. Since the Kirby Flow was good hard solid rock, the stuff around it eroded away while it was left standing. What once was a gash of a river valley is now a ridge standing above the surrounding plain – a clear demonstration of inverted topography.

Little Luna was also some tougher stuff – she looks pretty gneiss, actually. She forms a resistant hill, and also testifies to an orogeny that happened long before Kirby Mountain erupted. She was probably once a pretty granite pluton, which got buried many kilometers deep down in the earth during a mountain building episode. Heat and pressure softened her up enough to allow her minerals to recrystalize, and shearing action probably caused her lighter and darker bands, a process that formed a very nice gneiss. Eons of erosion brought her to the surface, where she now forms Little Luna Hill.

Kirby and Luna diagrammed

Kirby and Luna diagrammed

That’s geology with Geokittehs. I think Kirby and Luna did a fabulous job demonstrating some pretty neat geologic concepts. They’re not the only hard-working kittehs – you can find a lot more at the Geokittehs site where Evelyn does most of the heavy lifting and I pop in to contribute from time to time. Geology’s fun to begin with. Kittehs make it super-fun.

High-five, Kirby and Luna!

Kirby and Luna High Five

Kirby and Luna High Five

(Regular blogging will resume shortly. It’s been a mad few weeks. And yes, the kitten is part of that madness. How is anyone supposed to get serious work done with a tiny kitten causing them to collapse into a puddle of squee every fifteen seconds?!)

Dana Hunter About the Author: Dana Hunter is a science blogger, SF writer, and geology addict whose home away from SciAm is En Tequila Es Verdad. Follow her on Twitter: @dhunterauthor. Follow on Twitter @dhunterauthor.

The views expressed are those of the author and are not necessarily those of Scientific American.



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