Talk:Missoula floods

Kinetic energy quote

I removed this line:

The kinetic energy of the massive mass of water was approximately 2 terawatts (TW) - equal to the entire electricity consumption of the globe in 2005.1

b/c a Terawatt is not a unit of energy. I checked the source, but it makes the same mistake.

Nbrahms 17:44, 19 March 2007 (UTC)

Good catch. It's been a long time since I've sat in a science class, so my thinking's a little fuzzy here; but it seems that if there's a grain of truth to the quote, it would be worthwhile to re-phrase it in an accurate way, as the point it makes illustrates the power of the floods in a very visceral way. Is that a possibility, or is the claim just hopelessly misguided? -Pete 18:18, 19 March 2007 (UTC)

To be energy, the units would have to be something like terawatt hours, horsepower years (which is a silly one), or plain old joules, etc. It should also be clearer which part of the kinetic energy is specified: is it just the dam breach or the flow of water to sea level? Also, the phrase "massive mass" should be avoided (in the original text). —EncMstr 19:30, 19 March 2007 (UTC)

You can see my calculations on Talk:Dry Falls. I calculated how much kinetic energy the floodwaters contained, per second, as it flowed through Dry Falls - a certain amount flowing at a certain speed. This gives a figure of 2.08 x 10¹² Joules per second, which is the same as TeraWatts (Joules per second).

You are correct that my comparison of this figure with world electricity consumption was flawed. World eelectricity consumption over 2006 was 15.45 trillion kWh. If we divide by the number of hours in a year, to get the average amount of electricity used by the globe on an hourly basis, we get 1.7 TeraWatts per hour.

Dry Falls flowed continuously for at least 2-3 days, so we can use my TW/s figure as TW/h. If we could generate 2.0 TeraWatts per hour using the falls, and the world today uses 1.7 Terawatts per hour, we could power the entire globe for the period of greatest flow during the flood. I will edit the kinetic energy figure accordingly. Thanks for spotting my error.

Phew! Ppe42 23:33, 19 March 2007 (UTC)

"Terawatts per hour" is NOT a unit of energy

...or even power, for that matter. It would represent a _change_ in power, actually -- increasing or decreasing power. You can say "then the power increased at 2 terawatts per hour" but you cannot say "2 terawatts per hour of energy" or even "2 terawatts per hour of power". One watt = one joule/one second. One watt/hour = 3600 watts/second, and 1 watt/second = one joule per second PER second. This is a rate of change of a rate! Like how acceleration measures the change of velocity, which is a rate of motion (and is measured in similarly-patterned units -- meters per second _per second_.).mike4ty4 23:52, 25 March 2007 (UTC)

I think it was intended to be Terrawatt-hours, or 1,000,000 kWh. Cacophony 00:18, 26 March 2007 (UTC)

See the Talk:Dry Falls page for calculations used to arrive at the 2.0 TW kinetic energy figure. Moved from above; fixed wikilink.Walter Siegmund (talk) 03:07, 26 March 2007 (UTC)

The Idaho Museum of Natural History cites the flow of the Missoula Floods as 9.5 cubic miles per hour. Now the question is, at what point does this calucation become original research? Cacophony 01:04, 28 March 2007 (UTC)

The 9.5 cubic miles per hour number seems to refer to the peak discharge at the failed ice dam. That is how I read it. At Dry Falls, it would have been less because of alternative channels, including the present day channel of the Columbia River, and upstream empoundment. I doubt that the 9 cubic miles per hour at Dry Falls number that was alleged in the content that I removed is plausible. Regarding your question, I don't think NOR is intended to prevent the results of simple calculations from being included in articles. It is important, however, that the other editors be able to understand and verify the content. That depends on the difficulty of the calculation and the expertise of the editors. I do think NOR does apply to editors estimating the effect of alternate channels and empoundment on flow at Dry Falls. Walter Siegmund (talk) 07:14, 28 March 2007 (UTC)

While on the one hand, I want to stand by my calculation, given my assumptions ... I will respect that my little factoid about the kinetic energy of the floodwater verges on original research. Good work spotting my blog-reference, too.  :-) Ppe42 14:08, 28 March 2007 (UTC)

Natural disaster?

Wow, what an interesting debate above. Wish I had something to contribute - hope it gets settled at some point by those more knowledgeable than me.

I'm curious what people think about the term "natural disaster." This article has been added to two categories titled "natural disasters of ..." My sense is that a geological/meteorological event is consider a "natural disaster" when it has a disastrous impact on human civilization, not merely because it's big and moves a lot of stuff around.

I don't know what the human population was like in the northwest at the time of the Missoula floods, but I do know that the regional economic/cultural importance of Celilo Falls has been estimated at up to 10,000 years, and the Floods ended more like 13,000 years ago.

Was the region heavily populated, and if so, did the floods impact it disastrously? Would it be more accurate to classify it as a part of the region's "natural history?"

-Pete 01:55, 28 May 2007 (UTC)

Inline references sought

The article has been reordered and sectioned off to conform to the Wikipedia guide of style. If the article is to reach GA status, inline references are needed in all sections of the article. Technically, the article has enough info (if correct) to be B class. Without the inline references, it's hard to check the article's veracity, so I've left it Start class. Thegreatdr 05:34, 11 October 2007 (UTC)

Thanks GreatDr! I've been meaning to get around to this for some time. The article recently linked by Glacier109 will be tremendously helpful, it contains most of the information already in the article (and clarifies a couple other points, for instance that Bretz believed that there had been only one flood.) I'll try to contribute to this in the next few days -- hopefully a couple others will jump in as well! It would be very satisfying to see this improved to GA level, it's a huge component of the history of the Northwest. -Pete 06:52, 11 October 2007 (UTC)

Jökulhlaups are not glacial lake floods. They are specifically floods created by subglacial volcanoes, and are fairly common in Iceland, where there are several vents beneath the ice cover. Glacial lake floods are simply glacial lake floods. —Preceding unsigned comment added by 208.54.95.28 (talk) 19:51, 12 January 2008 (UTC)

Citation for recent change?

Tiptoety -- or anyone -- can we get an inline citation for this change? I'm pretty sure most of the sources I've seen have used 40 as the "ballpark" number, not 70. But I don't consider myself an expert, and don't remember for sure. Whatever the number is, it should have a clear citation. -Pete (talk) 22:50, 13 February 2008 (UTC)

I've flagged the contradiction. I don't have any sources but, if the flooding events occurred about once every fifty-five years for about 2000 years, we get about thirty-six flooding events, which is close enough to forty. Since both statements of the 55-year frequency and 2000-year duration are attributed to geologist weasels, it's hard to be sure. :-) Dricherby (talk) 13:14, 20 May 2008 (UTC)

In an interview Vic Baker of the University of Arizona mentions "scores of floods, maybe 100 or more" (Fantastic Floods). --Hans-Jürgen Hübner (talk) 09:20, 11 July 2008 (UTC)

Flood creation

Is the explanation for the catastrophic failure of the ice dam generally accepted by geologists? I am not a geologist, but I do not know what can be wrong with the traditional explanation, that the water in Lake Missoula eventually became deep enough to float the ice that formed the dam. The water at the lake bottom would have been at the temperature of maximum density, already well above the melting point, so exotic mechanisms such as the one given in the article would not be necessary to melt the ice in contact with the water. If geologists no longer accept the simple argument, can someone tell me what is wrong with it? PKKloeppel (talk) 02:18, 13 September 2008 (UTC)

Discharge and "velocity."

at least twenty-five massive floods, the largest discharging 2.6 billion US gallons per second (9.8×10^6 m3/s).[1] The peak velocity of the largest floods is estimated to be 40 to 60 cubic kilometers per hour.[2]

The "peak velocity" line doesn't make any sense. km³/hr is rate of flow, not velocity. The figure given by the first line is equal to 35 km³/hr. So we just said, "the largest flood discharged 35 cubic kilometres per hour. The largest flood's discharge is estimated to have peaked at 40 to 60 cubic kilometres per hour.

I don't know if these are two different, incompatible estimates by two different sources, or if the first is talking about sustained flow while the second is looking at a short-term peak rate of flow. Does anyone have the original source handy? <eleland/talkedits> 19:02, 7 July 2009 (UTC)

Peak velocity corrected - good catch. As to the difference in flow rates, the literature is replete with options. Short of pulling some geology publications and deciding which to cite, I chose to shotgun a few of those written for the general public. Take a look & see if this helps. Thanks - Williamborg (Bill) 02:13, 8 July 2009 (UTC)

First recognized by Bretz?

I wonder about the use of first recognized by Bretz. David Thompson in 1811, Samuel Parker in 1835, Lt Johnson of the Wilkes Expedition (US Ex Ex) in 1841, Territorial Governor Stevens and his staff in 1854-55, an aide to General W. T. Sherman in 1883, and others, all commented that there had to have been an epoch flooding event in the area covering the whole Columbia Basin. Here is what Colonel Tidball wrote: "The terrace formation before mentioned is due no doubt to a lake formerly occupying all this country. At that epoch it was bounded on one side by the Cascade range of mountains, and in bursting at successive periods through this range at the Dalles left deposits in the form of successive benches." Page 83 of The Official History of the Washington National Guard, Volume IV, Washington Territorial Militia in the Philippine Insurrection, Headquarters, Military Department, State of Washington Office of the Adjutant General (Washington National Guard), c. 1967, WASH ANG PAM 210-1-4 – via Washington National Guard State Historical Society, http://mil.wa.gov/uploads/pdf/history/fields_vol_iv.pdf . As I look through written stories about Eastern Washington the implication Bretz was the first to realized there had been a great flood bothers me. Srichart4 (talk) 16:16, 22 April 2015 (UTC)

Fascinating, thanks for sharing that Srichart4. I am not a geologist or expert in any way; but my guess is that Bretz was the first to scientifically add a great deal of specificity to those speculations, and deserves some credit in that respect. I wonder if this topic has been explored overall in any scholarly works? Do you have specific suggestions for how this article should be improved, or just looking for general reflections on that point? -Pete (talk) 18:51, 22 April 2015 (UTC)

Just looking for general reflections on the point. I'm not going to go into a geology-oriented article and make corrections. I'm too new at wiki editing to be that brave.Srichart4 (talk) 21:22, 23 April 2015 (UTC)

glacial outburst floods are prehistoric, right?

The article states (referring to glacial outburst floods) that they have happened "many times in recorded history." Unless I am mistaken, none have happened in historical times, and all were in fact prehistoric events, and none have occurred in "recorded history. Swauden (talk) 02:31, 17 January 2021 (UTC)

Wrongly labeled photo

The photo that is labeled as "The Channeled Scablands of Eastern Washington" appears to be incorrectly labeled. Upon investigation of the file, it seems to be a photo of Markle Pass in Montana. It should either be removed or replaced. Alextheunicorn (talk) 18:34, 22 February 2022 (UTC)

The photo was mislabeled, good of you to point it out. The photo, properly captioned as Markle Pass, is still relevant to the article and it should be kept. Paleorthid (talk) 00:11, 23 February 2022 (UTC). Copyedit 00:21, 23 February 2022 (UTC)

Magnitude of Missoula Megafloods Possibly Greatly Overestimated

A recent paper argues that the Missoula Floods might have been 80 percent smaller than currently estimated. Go see:

Dzombak, R. (2022), Western U.S. “megafloods” might not have been so mega, Eos, 103, https://doi.org/10.1029/2022EO220069. Published on 3 February 2022.

Lehnigk, K.E. and Larsen, I.J., 2022. Pleistocene Megaflood Discharge in Grand Coulee, Channeled Scabland, USA. Journal of Geophysical Research: Earth Surface, 127(1), no. e2021JF006135. https://doi.org/10.1029/2021JF006135

David, S.R., Larsen, I.J. and Lamb, M.P., 2022. Narrower Paleocanyons Downsize Megafloods. Geophysical Research Letters, no. e2022GL097861. https://doi.org/10.1029/2022GL097861 Paul H. (talk) 01:01, 26 October 2022 (UTC)

Fortunately, the lede of the article is conservative and used a 2006-era estimate of 2.7 million cubic meters per second, which is very close to the Lehnigk estimate of 2.6 million cubic meters per second. The article cites a high estimated flow rate of 17 million cubic meters per second from 1986. I'll edit that with a high estimate of 7.6 million cms from Lehnigk (which is close to the high estimate of 7 million cms from David). — hike395 (talk) 14:02, 26 October 2022 (UTC)

Are dates calibrated or radiocarbon?

The date 15,000 BP as referenced in the main article at this point is most likely a radiocarbon date, as an age greater than 20,000 BP is likely for the initial Missoula floods. 15,000 RCYBP calibrates in the NW of North America to ~20,000 BP. Thaddeus Andres Gutierrez 09:34, 14 October 2023 (UTC) — Preceding unsigned comment added by Fulguritics (talk • contribs)