Scablands

Re: Scablands


The "formula" for creating a Channelled Scabland involves a large lake which is held in check by a glacial dam which breaks at some point, releasing a lot of water in a short period of time.

I don't know if there are any large bodies of water currently held in check by glaciers, but there probably are. As to whether it will happen in our lifetimes, we would need to determine if there are any glacial dams which are small enough, and are receding fast enough to break in the next hundred years or so.

Farmerman will probably know more about the current geologic structures than I do.

Catastrophic floods of this type also happen for different reasons. For example, there is good evidence that the Mediterranean Ocean has been repeatedly drained and re-filled from the Atlantic catastrophically quickly. This is due to geological activity which opens and closes the straights of Gibralter.

I believe something similar happend to either the Caspian Sea, or the Black Sea, but I can't remember which.

That name seems inappropriate applied to the beautiful earth.Only died-in-the-wool materialists would use a word like that for those scenes.

The Scablands are places like Tokyo and New York and the rolling countryside all planted up with the cash crops and the streets and all the other **** that's on them.All that stuff looks like scabs from either close in or from a distance.Feels like scabs too some of the time.

Destiny shapes things not causes.

Geologically the scablands of E Wash state are an example of how multiple sets of data and open ended hypotheses work to arrive at a solution for hown a hell these gulleys were carved.. V Baker (never met the guy) published in a GSA Special Paper (N0.144, I use it in classes as an example of multiple data sets and conceptual model development). Baker took all the data we knew about the scablands and came up with a beautiful and really sweet explanation. He first looked at the Mega ripple marks on the surface of the channel. These ripples were over 10Meters in height (thats over 30 ft for each ripple to trough) That implied one hell of a lot of energy went into the waterway in the channel. He also saw thatn coarse gravels were bedded in arrays that obeyed Stokes law and Hjolstrums law of deposition. Baker estimated by creating a channel flow equation that calculated stream flows at about 100 to over 130 Km/hr (Theres a "Six power rule that states that the energy in a channel is roughly equivalent to the velocity increase value---TO THE SIXTH POWER. He measured his "sand grains ' and found that some of them were as big as a bus.
He then compared the evidence of the scouring and the "hanging valleys that were evidence of earlier streams that debouched into the biggest channel. WHen he did all his calulations and conceptual modelling, he did a best fit nomograph (computers were toys in the early 70s) and he came up with a total discharge volume and then he traced this back to what hed consider as headwaters. There, behold, he found evidence of a huuuge lake that was, as ros said, dammed by ice and debris. Lake Missoula was hundreds of miles upstream of the present scablands and theories vary that it took anywhere from 1 to 6 months to complete the dischrge event. Since we dont have any big Continental sheets (remember that the highest stage of the Pleistocene glaciation had an ice sheet about 3.5 Km thick) When this began melting rapidly over 22000 years ago, the bound up free water was being held often at grades higher than normal base. Also , since most of the ice sheet had captured over 90% of the worlds fresh water, the sea levels were down over 100 meters lower than today. So there was one hell of a vertical gradient. In order to see that today, wed need a huge lake somewhere up in the Himalayas. And, fortunately, we dont see one.
So I wouldnt worry about glacial lakes messin with your mountain home. Id be more concerned about sea level rise.

Damn, that would have been one hell of flood to see.

Move over, Genesis. Break out the gopher wood.

Thanks for the explanations ros and farmerman.

Boy are the brits fiesty today.....

fm-

Loved it man!I bet you laughed all the way through too.I did think though that "1 to 6 months" was a bit of an idle boast.You would need an Art's Council grant to prove that.

spendius. Besides the hydraulics in emptying a huge bowl, roughly half as big as Montana and dumping it over a natural" weir" that can be seen at the head of the channeled scabs, the math is quite easy. (I can understand your unfamiliarity with quantitation, being a philosopher and all)
Included within the sediments of the large "sand and boulder ripples" and clay deposits on the ends of moraines, there has been enough paleopollen and wood sampling to cross plot and come to the approximate duration. The wood samples appear all to be within a single season, so, with that as an outside estimate of 6 months and the hydraulics computed by topo and volumetric drainage the range is about as good as well see. Did you ever wonder how, when it rains X inches near Alton Illinois, that NOAA can compute the heighth of a flood crest on the Mississippi at Baton Rouge to the nearest hour?. (HINT--it has to do with numbers)

You can still find GSA papers on the scabs and there are a number of other papers on this very phenom. I dont claim to be an expert, just someone who knows how to use multiple data in my classes. The students provide me with even greater depth of knowledge as they go off and hunt . The scabs are best seen from the air, a 30 ft ripple mark can be quite impressive especially when there are thousands more very similar in appearance to barchan dunes .

Thanks Farmerman, and ros for the explanation. I knew it already.

Yes, my concern is the sea levels. I just did not know how to approach the question, so I gave the scablands as an example.

Please, how would you explain the melting of the glaciers today? Is it the same way the Missoula glaciers melted? Or is the added heat from the underground volcanic activity also causing rapid melting?

Thanks

The chemical stew promised by the high-tech developments of the 'scablands' in the US has brought in a series of new technical terms on the other side of the atlantic. Here, the technical term for the US cities is the Twatlands. New terms are mooted when carbon dioxide induced vapourisation begins in earnest.

Thank you JJ, but that does not answer my question. Twatlands ooooook.

It's alright folks.He doesn't bite.

But you do :wink:

Assertion Angel.Show us the teeth marks.

I heal very fast, and don't scar.

That is a defining characteristic of a healthy immune system.

Oh yes, I'm a very healthy person. I have been told that because I am I will live a long time. That I do not look forward to. I don't want to be very old.

One shouldn't look for dark clouds in silver linings.

Angelique-The melting of continental glaciers was related to the earths orbit and axis. Look up the Croll-Malenkovitch cycles and they can display more than youll need.
Basically the earth' orbit around the sun gets flattened (eccentricity) in a cycle thats about 1-4CK years. Then the axis of rotation has a built in tiny oblique wobble thats about a 41K year max. On top of theis is a 23000 year precession of the axis (which is a super wobble that takes the earth down to about 65degrees to the excliptic) All three of these act to start and stop glaciation by increase or decrease of solar rad. We can see this by measuring excesses of specific oxygen isotopes which are increased in ratio in warmer times as O16 gets driven into the atmosphere and its ratio decreases in colder times because )16 is incorporated into sea water more

If you put either cRoll-Milankovitch or just try Milankovitch cycles into google you should get a ton of stuff.

Glacial melting today is a t a max Milenkovitch wobble cycle and the atmospheric content as "supposedly" man induced is still (as far as Im concerned) not a slam dunk proven issue. Id better leave before I get pilloried by the clean air contingent