Mount Spokane Comments
[ Post a Comment ]
|Fred Spicker||Not volcanic|
|Mount Spokane is NOT volcanic in origin. It is an uplifted and eroded portion of the Mount Spokane batholith - a pluton, not a volcano. It is granite intruded and hardened at great depth.|
Not on line – but you may want to look it up:
A PETROGRAPHIC AND GEOCHEMICAL STUDY OF THE MOUNT SPOKANE PLUTON AND ASSOCIATED DIKE ROCKS AT DART HILL, SPOKANE COUNTY, WASHINGTON: ERNST, Shawna L. and THOMSON, Jennifer A., Department of Geology, Eastern Washington Univ, 130 Science Building, Cheney, WA 99004-2439, email@example.com
|Posted Dec 18, 2006 4:21 pm|
|redsplashman23||Re: Not volcanic|
|These is my source for it being volcanic: Wikipedia, Answers.com, and America's Volcanic Past |
|Posted Dec 18, 2006 4:34 pm|
|Fred Spicker||Re: Not volcanic|
|Wikipedia is hardly an authoritative source for anything – anybody can enter or edit anything on the site.|
Nowhere on the USGS site does it list Mount Spokane as a volcano – because it is not a volcano. The one place that they mention it they talk about the granite rock type – not a volcanic rock type.
Mount Spokane is simply NOT a volcano – read the reports that I referenced. They are done by professionals.
I have an MS in geology. I live in Spokane. I have been up Mount Spokane more times than I can count. I was on the summit yesterday. The rock is granite.
|Posted Dec 18, 2006 4:46 pm|
|Thanks for putting up this page. It could use more info in the overview. And, as the right Fred said, Mt. Spokane is not really volcanic in origin. Sure, one could say the emplacement of a massive wedge (pluton) of rock is a volcanic process, but saying a mountain is of volcanic origin implies it formed like a volcano--by the eruptive process of molten rock or ash.|
Some things you could improve upon:
The summit is actually 5883, not 5889. Look more closely at the map here. Instead of 33, you should use the ordinal 33rd. Lastly, your link to Jeff's prominence list implies the peak is in a category of peaks with 2,000 feet of elevation. You should put the word prominence in the link, as in "2,000-ft prominence peaks in Washington."
|Posted Dec 18, 2006 5:17 pm|
|Fred Spicker||Re: Thanks|
|Actually, one cannot argue that the intrusion of a pluton is a volcanic process.|
Volcanic means that the process had something to do with the actual existence of a volcano.
definition - volcanic
The intrusion of magma into surrounding rock forming a pluton does not necessarily result in volcanic activity above. And, in most cases for plutons such as batholith formed at considerable depth (5 to 30 km), it does not.
I know - picky, picky, picky :-)
|Posted Dec 18, 2006 6:21 pm|
|Depending on where you look some documentation says that Mt. Spokane is 5,883 and some say 5,889. The Mountain Info link for Mt. Spokane lists it as 5,889. Here is a Google Search with many sources listing it as 5,889. Many topographical maps get outdated and elevations get updated a lot. For instance, Mount Whitney use to be listed as 14,494, then 14,495. Now it is officially 14,505.|
|Posted Dec 18, 2006 7:02 pm|
|Fred: note I didn't say "one could argue" I said "one could say." I know, picky picky picky :-) I'm with you on this, the upward emplacement of a batholith of granite or whatever the rock does not constitute a volcanic process.|
Redsplashman: the summit is 5883. That's what the map says. It could be theorized that those who say it is 5889 are those who aren't looking closely at the map and are misinterpreting the contour line crossing in front of the 3 as closing it to form a 9. And, of course, the benchmark says 5881 but it may not be atop the exact highest point/rock.
|Posted Dec 18, 2006 7:18 pm|
|The intrusion of magma into surrounding rock forming a pluton does not necessarily result in volcanic activity above.|
Part of the problem that confuses people is that some national park or national forest signs, some books, and various other sources use the word "volcanic" in place of "igneous" or "magma", which as you point out is incorrect.
Hahns Peak, north of Steamboat for example is a laccolith, but the forest service information and some books call the peak "volcanic". On our last visit to the Grand Canyon (Thanksgiving), we read something that said something like "granite is volcanic rock that cools underground". They should have said igneous rock instead of volcanic.
The misinformation out there definately confuses people.
|Posted Dec 18, 2006 8:21 pm|
|I've been wondering when someone would post this mountain. I have to agree with all the comments above. Minor edits that would improve the page. Mt. Spokane is an interesting place and given its position, the views from the summit are really special. I believe something like 8 lakes can be seen. Thanks for posting this page.|
|Posted Dec 18, 2006 6:49 pm|
|redsplashman23||Re: Mt. Spokane|
|I agree that this page was long over due. I lived in Spokane for 3 years and now live in Las Vegas. I noticed this mountain has never been posted and thought it was time it was. Thanks for all the inputs from everyone!|
|Posted Dec 18, 2006 7:04 pm|
|desainme||I think I saw Mt. Spokane|
|from Town or driving in/out as I was going through "The Valley" on I-90. Really could not tell which top was it though. Glad to hear it is not a volcano but like Mt. Katahdin a granite pluton. Looks like a nice hike.|
|Posted Dec 18, 2006 7:12 pm|
|First paragraph: "from hiking to [link]Mt Spokane" should be "from hiking to [link]skiing"|
PS the NGS publishes the positions of all its benchmarks; I found one right by the summit with a listed elevation of 5887 feet (NAVD 88), which is a bit of a problem if the summit is supposed to be 5883.
Of course, arguing about the height of a mountain down to a few feet is quite silly. You can get differences of several meters by choosing a different sea-level model and just as much from measurement error.
Edit: This appears to be a "horizontal control point", not an elevation benchmark, so its vertical position should be taken with a grain of salt.
Edit 2 I think this is actually a VABM, so its vertical precision should be decent after all. Under the previous definition of sea level, this benchmark would have been at 5883 feet, which explains the Topozone map. If I'm right about this being the same marker as seen in Dean's photograph, the true elevation (at the marker) is probably 5887; the "5881" on the physical mark is a transcription error (I think the calculations were done in metric which makes a transcription error in the other direction very unlikely).
SV1719 DESIGNATION - Y
SV1719 PID - SV1719
SV1719 STATE/COUNTY- WA/SPOKANE
SV1719 USGS QUAD - MOUNT SPOKANE (1996)
SV1719 *CURRENT SURVEY CONTROL
SV1719* NAD 83(1991)- 47 55 24.95744(N) 117 06 43.84565(W) ADJUSTED
SV1719* NAVD 88 - 1794.4 (meters) 5887. (feet) VERTCON
|Posted Dec 18, 2006 7:34 pm|
|According the the USGS official place names page, Mt Spokane is 5853 feet high, but my guess is that they cannot read their own maps! I could swear that the benchmark near the Vista House actually says something like 5888 ft (but the last 8 might actually be a 3 - it's pretty worn)|
|Posted Dec 18, 2006 8:00 pm|
|The USGS GNIS system gives coordinates near the lookout tower, not the summit (which is by Vista House).|
|Posted Dec 18, 2006 8:08 pm|
|In looking at the pic of the benchmark I posted, it looks like 5881 is stamped on it. That poor benchmark sees way too much traffic.|
|Posted Dec 18, 2006 8:30 pm|
|(edit: I leapt to a wrong conclusion. That's a VABM mark, as Klenke says below, so both elevation and horizontal position were measured)|
|Posted Dec 18, 2006 8:57 pm|
|Moni: by the USGS's admission, many of the elevations in their database are incorrect. The Mt. Spokane case is no different.|
Dean: Is it possible there is more than one benchmark up there? I don't know myself as all was snowcovered when I got up there. Your photo is of the vertical angle benchmark. Often times another non-VABM benchmark can be found nearby.
But the most pressing point about the elevation is a) should one believe the (most current map) or b) believe information presented elsewhere (like the google searches redsplashman put forth)? The map says what it says and until someone can prove that elevation is defunct, that's the elevation that should be used (5,883 ft).
What is shown on the most current USGS map? The 5883 elevation may be from the 1986 map. Is there a newer map?
|Posted Dec 18, 2006 9:00 pm|
|It is possible that there is another benchmark but as you can tell from the shot I have of the summit house, I too hit the area when snow ruled. What you are saying makes sense to me.|
|Posted Dec 18, 2006 9:04 pm|
|Wow, so many comments about Mt. Spokane! Must be a slow day at work for everyone. It is for me.|
I note that the map does not have a VABM reference next to the summit triangle denoting a VABM (example: Jordan BM; I have been up this peak and can confirm a VABM being up there...along with a non-VABM marker). But the mere fact that "VABM" is missing from the map for a peak does not mean there isn't a VABM benchmark on its summit, as the case for Mt. Spokane proves.
Here are examples of the type of BM nartreb is talking about with a cross hair through the triangle: Granite Mountain 7366 ft and Mt. Pilchuck 5340 ft as opposed to the non-cross hair type (seen in the Jordan BM link above).
|Posted Dec 18, 2006 9:22 pm|
|I'm starting to think that the mark Dean photographed and the mark I found online are the same one. "Mine" is SV1719, which shows up through the NGS interactive map but not their "search by location" feature. It also shows up on geocaching.com's search page. There are a few other marks nearby, but I don't see any others with a "Y" designation. The mark in the photo clearly has that "Y" designation. The datasheet for SV1719 says 5887ft, the mark in the photo clearly reads 5881. Could be a transcription error, but in which direction? |
Another option: the physical mark preceds the adoption of NAVD 88. Hm, under NGVD 29 the height would be 5883. That certainly explains why that number appears on so many USGS maps (eg, Topozone, which is perennially outdated). But it's not 5881.
|Posted Dec 18, 2006 9:36 pm|