Topic 99 of 99: geomorphology
Fri, Apr 7, 2006 (05:42) |
Paul Terry Walhus (terry)
Geomorphology is the study of how
land forms evolve and change - I know it has several branches like
fluvial geomorphology, but when 250,000 cubic metres of rock falls
off for example is that not an act in the evolution of the
surrounding landscape?
Or what about when a debris avalanche plugs a river, forcing it to
either over top the dam or find a new course?
Thus spake Rob Glennie.
28 responses total.
Topic 99 of 99 [Geo]: geomorphology
Response 1 of 28: Curious Wolfie (wolf) * Sat, Apr 8, 2006 (22:04) * 1 lines
and very well too. it's neat to see where we slice through earth and can see the changes it went through.
Topic 99 of 99 [Geo]: geomorphology
Response 2 of 28: Marcia (MarciaH) * Sun, Apr 9, 2006 (14:31) * 1 lines
Good Rob! I was including this stuff in Mass Wasting and Diastrophism but here is even better. Now tell me all about a destructive earth. I just lived thru a week of the most intensive toradoes on record for this area. Eleven died south of us.
Topic 99 of 99 [Geo]: geomorphology
Response 3 of 28: Curious Wolfie (wolf) * Mon, Apr 10, 2006 (19:08) * 1 lines
oh yes, that was all over the news. the AM said he was shocked that the damage was done to those brick homes vs all the trailer homes we usually see. still amazing how it can hit one house and leave the one next door alone.
Topic 99 of 99 [Geo]: geomorphology
Response 4 of 28: Marcia (MarciaH) * Mon, Apr 10, 2006 (19:52) * 1 lines
That is the problem with tornadoes. You an more or less predict where lava flows are going to go. With tornadoes, you find caprice and not logic. I can opt to go see a lava flow. Tornadoes make house calls !
Topic 99 of 99 [Geo]: geomorphology
Response 5 of 28: Curious Wolfie (wolf) * Tue, Apr 11, 2006 (18:55) * 1 lines
indeed! with lava, you have time to get out of the way (for the most part).
Topic 99 of 99 [Geo]: geomorphology
Response 6 of 28: Rob Glennie (southernalps) * Wed, Apr 12, 2006 (06:39) * 7 lines
Kia Ora
Thanks Terry. Marcia, if I scan them to the computer, and e-mail them to you, would you like to put up some cool pics from Franz Josef which I will use to explain the geomorphological processes there.
Okay, okay, maybe you cannot see them very clearly - these processes usually only reveal themselves if the geomorphological environment has been upset by something as drastic as an earthquake. However maybe by seeing the land as it looks now, and then see it after a major event and you will get an appreciation for geomorphology in action.
Rob
Topic 99 of 99 [Geo]: geomorphology
Response 7 of 28: Marcia (MarciaH) * Wed, Apr 12, 2006 (18:21) * 1 lines
Sure Rob ! Send them to me at critter514@aol.com. Thanks. No matter they are not as clear as you'd like. They are far better than none at all.
Topic 99 of 99 [Geo]: geomorphology
Response 8 of 28: Curious Wolfie (wolf) * Thu, Apr 13, 2006 (18:07) * 1 lines
oooohh, hurry up, i wanna see *grin*
Topic 99 of 99 [Geo]: geomorphology
Response 9 of 28: Marcia (MarciaH) * Thu, Apr 13, 2006 (21:48) * 1 lines
Yes indeedy. It s Geo 89. Enjoy! You might like to add to the American Folkways please!
Topic 99 of 99 [Geo]: geomorphology
Response 10 of 28: Rob Glennie (southernalps) * Wed, Apr 19, 2006 (08:00) * 10 lines
Kia Ora
Marcia. In your e-mail please find two photos attached of the Waimakariri River. I
scanned them in last year when I was writing a mock resource consent application for an environmental science paper. Could you please put them up here?
People. I have for you two photos of one the finest examples of a BRAIDED river - a river with multiple channels lined by alluvial sediment and subject to the processes of fluvial geomorphology - that you will see anywhere in the world. With the exception of Alaska where a couple exist and maybe in the Soviet Union, it is unlikely you will see any examples anywhere else in the world that are this good.
The best example would have to be the Rakaia River. For most of it's 145km course, the Rakaia River is a mass of braided channels on a riverbed more than a mile wide at the township of Rakaia. In low flow - 250 cubic metres per second or less - most of the multitude of channels are fordable. In full flood the whole riverbed is a single brown torrent running at anything up to 6000 cubic metres per second.
Rob
Topic 99 of 99 [Geo]: geomorphology
Response 11 of 28: Rob Glennie (southernalps) * Wed, Apr 19, 2006 (08:03) * 5 lines
Kia Ora
http://www.dantecdynamics.com/applications/Images/backdropM.jpg - Rakaia River from the air. All the blue streaks are river channels meandering all over the river bed.
Rob
Topic 99 of 99 [Geo]: geomorphology
Response 12 of 28: Paul Terry Walhus (paul) * Wed, Apr 19, 2006 (08:36) * 2 lines
Topic 99 of 99 [Geo]: geomorphology
Response 13 of 28: Paul Terry Walhus (paul) * Wed, Apr 19, 2006 (08:36) * 1 lines
Just being a smartypants and posting the picture Rob pointed to.
Topic 99 of 99 [Geo]: geomorphology
Response 14 of 28: Marcia (MarciaH) * Wed, Apr 19, 2006 (17:35) * 1 lines
Terry, Rob's two latest are on their way to you. Please post them too. They remind me of the Missouri and Mississippi rivers at the confluence. It is braided all over the place in what is called the American Bottoms which is the richest farmland in North America. What is the land like around the braided pictures you are posting?
Topic 99 of 99 [Geo]: geomorphology
Response 15 of 28: Rob Glennie (southernalps) * Wed, Apr 26, 2006 (23:11) * 10 lines
Hi all
Okay. Cool. Terry has the pic of the Rakaia River up.
This airborne shot is taken looking inland towards the foothill ranges of the Southern Alps. You can see that the river is very braided here, and thus appears like this for most of its 145km run from the Alps to the Pacific Ocean. If you look at the land immediately left of the river, you can see older river channels that were active when the river had meandered over to that side of its course.
If you look about 3/4 of the way up the photo you can see what I think is a glacial moraine extending into the river, which was left from the last ice age when the big braided river valleys were conduits for the glaciers coming off the Southern Alps.
Most of those river channels are 1-3 metres deep. None of them exist in the array that you see there, as their network changes with each flood event that comes down the river - as recently as Tuesday the Rakaia had a 1050+ cubic metre per second flood going down the river.
Rob
Topic 99 of 99 [Geo]: geomorphology
Response 16 of 28: Rob Glennie (southernalps) * Wed, Apr 26, 2006 (23:39) * 9 lines
Kia Ora
http://spring.net/geo/rob/
Thanks for that Terry. Now to explain a braided river to people who haven't seen them before...
Essentially what you are looking at is a river with multiple channels meandering over a riverbed that here, is about 750-1000 metres wide. In these photos of the Waimakariri River after rainfall in the mountains, the river is running high and dirty. The channel closest to you in the bottom pic is usually about half as wide and blue when the river is low. You can see that the river is just starting to drop (notice wet rocks on edge of channel in top photo). In high flood, all 750-1000m of river bed width will be under water - the number of people who get caught out on braided river beds or who simply don't understand Canterbury weather is amazing. Centrifugal forces shape the channel. Just as water running down the edge of the shower wall seems to bend for no apparent reason, the same happens in river channels. The gravel on the river bed is all alluvial sediment washed down by thousands and thousands of years of fluvial geomorphology in action.
Rob
Topic 99 of 99 [Geo]: geomorphology
Response 17 of 28: Marcia (MarciaH) * Thu, Apr 27, 2006 (19:06) * 3 lines
Thanks Terry. Is this the way future graphics will be put on Geo if they are not already on the interet?
Great stuff, Rob. I am so happy you have returned. Rivers are new to me as neighbors. I find them fascinating. We were on the Indiana side of the Ohio not long ago and noted that what seems like a peaceful river had flung trash 20 or 30 feet into the tops of trees on the last flood stage. I am happy we are several miles from the main course.
Topic 99 of 99 [Geo]: geomorphology
Response 18 of 28: Paul Terry Walhus (terry) * Tue, May 2, 2006 (21:44) * 1 lines
Sure, I can help you get set up to post graphics. Download filezilla.
Topic 99 of 99 [Geo]: geomorphology
Response 19 of 28: Curious Wolfie (wolf) * Wed, May 3, 2006 (11:13) * 1 lines
what's filezilla? afore i go and download it myself!
Topic 99 of 99 [Geo]: geomorphology
Response 20 of 28: Paul Terry Walhus (terry) * Wed, May 3, 2006 (12:27) * 1 lines
It's a real easy to use ftp program that will let you put pictures on the spring servers.
Topic 99 of 99 [Geo]: geomorphology
Response 21 of 28: Marcia (MarciaH) * Wed, May 3, 2006 (13:11) * 2 lines
Ok Will do that. Meanwhile this just came thru
-- Tsunami warnings issued for Fiji and New Zealand after earthquake measuring a magnitude of about 8.0 shakes southern Pacific Ocean.
Topic 99 of 99 [Geo]: geomorphology
Response 22 of 28: Marcia (MarciaH) * Wed, May 3, 2006 (13:11) * 20 lines
A magnitude 8.0 earthquake IN TONGA has occurred at:
20.03S 174.23W Depth 16km Wed May 3 15:26:35 2006 UTC
Time: Universal Time (UTC) Wed May 3 15:26:35 2006
Time Near Epicenter Thu May 4 04:26:35 2006
Eastern Daylight Time (EDT) Wed May 3 11:26:35 2006
Central Daylight Time (CDT) Wed May 3 10:26:35 2006
Mountain Daylight Time (MDT) Wed May 3 09:26:35 2006
Pacific Daylight Time (PDT) Wed May 3 08:26:35 2006
Alaska Daylight Time (ADT) Wed May 3 07:26:35 2006
Hawaii Standard Time (HST) Wed May 3 05:26:35 2006
Location with respect to nearby cities:
155 km (95 miles) S of Neiafu, Tonga (pop 3,000)
160 km (100 miles) NE of NUKU'ALOFA, Tonga (pop 37,000)
455 km (280 miles) S of Hihifo, Tonga
2145 km (1340 miles) NNE of Auckland, New Zealand
Topic 99 of 99 [Geo]: geomorphology
Response 23 of 28: Paul Terry Walhus (terry) * Wed, May 3, 2006 (13:12) * 1 lines
I just saw that on MSNBC. It hit Tonga. It's off the East Coast of Australia. Will Hawaii feel this?
Topic 99 of 99 [Geo]: geomorphology
Response 24 of 28: Marcia (MarciaH) * Wed, May 3, 2006 (13:13) * 1 lines
Expect more large earthquakes from various parts of the world as the struck bell effect sends reverberations throughout the planet.
Topic 99 of 99 [Geo]: geomorphology
Response 25 of 28: Marcia (MarciaH) * Wed, May 3, 2006 (13:27) * 1 lines
Hawaii may be affected. Dropping a pebble in a lake spreads the waves to every corner.. thus it is possible - though much reduced in strength over long distances.
Topic 99 of 99 [Geo]: geomorphology
Response 26 of 28: Rob Glennie (southernalps) * Thu, May 4, 2006 (05:07) * 7 lines
Kia Ora
Ideas that this was near Oz are fiction. It was nearly 1000km away. Oz might have felt it, but like everyone else outside of Nuku'alofa and American Samoa that thought a tsunami was coming, they were dreaming if they thought they saw a fluctuation in the water level.
Australia has no plate boundaries or subduction zones in its waters.
Rob
Topic 99 of 99 [Geo]: geomorphology
Response 27 of 28: Curious Wolfie (wolf) * Thu, May 4, 2006 (10:32) * 3 lines
well, i certainly am glad you are safe.
btw: i didn't catch any of this on the news (abc) last night, unless i missed it....
Topic 99 of 99 [Geo]: geomorphology
Response 28 of 28: Marcia (MarciaH) * Thu, May 4, 2006 (11:55) * 1 lines
Thanks, Rob. That is why I went to the Honolulu newspaper for their report. It was more reliable than local news here. Thank goodness it was pretty harmless.
Geo conference 
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