The Naked Scientists

The Naked Scientists Forum

Author Topic: Geology Question of the Week  (Read 166670 times)

Offline ichnos

  • Jr. Member
  • **
  • Posts: 38
    • View Profile
Geology Question of the Week
« Reply #75 on: 16/04/2007 12:48:02 »
As described previously the red sediments with green mottles can be attributed to roots within fossil soils. The mottles represent areas of reduced iron, produced from anaerobic decay of organic matter in a fossil soil with a fluctuating water table. I would like to add that EXODUS is WRONG in that just because a sediment is RED does not mean it was formed in arid conditions (CHECK ALFISOL SOILS). Red soils are also found in humid climates and the drab haloed roots or burrows (green  mottles)suggest that the water table fluctuates temporarily. The idea that red = arid is old news - get with it!  ;)
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #76 on: 03/05/2007 01:04:36 »
Which river carries the highest sediment load? This is for the whole world.
 

Offline ichnos

  • Jr. Member
  • **
  • Posts: 38
    • View Profile
Geology Question of the Week
« Reply #77 on: 03/05/2007 14:54:15 »
Is it in total discharge or per volume water per year or per day?
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #78 on: 03/05/2007 17:50:49 »
No. Sediment load is the total solids moved, both the mud and small sands in suspension and larger particles moved by saltation and other methods, e.g., by ligifaction, etc., along the bottom of the stream bed.

 

Offline ichnos

  • Jr. Member
  • **
  • Posts: 38
    • View Profile
Geology Question of the Week
« Reply #79 on: 03/05/2007 18:50:55 »
yes, what you say is correct, however, the sediment load can vary significantly seasonally. Are you after the river that can carry the maximum possible sediment load at any one time? or the river that carries the highest mean sediment load for say a year? I have asked around if anyone knows the answer (we're academic geologists of one type or another! ???). There is a suggestion that a river in a glaciated area may carry the highest sed load seasonally but that a river such as the Bramahputra may carry the average highest sed load..  :)
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #80 on: 04/05/2007 03:07:10 »
Well, then you have already got part of the answer. The Bramahputra-Ganges system has the highest sediment load, month from month. Most people think only of the Bramahputra OR the Ganges, not realizing that they merge 100+ miles from sea, forming a river with the highest sediment load, however you look at it. Also remember that the Bramaputra and the Ganges ARE rivers originating in a glaciated area. Together, they have the highest sediment load season by season.
« Last Edit: 04/05/2007 03:09:27 by JimBob »
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #81 on: 04/05/2007 03:34:30 »
What type of rocks are these?


 

Offline Bass

  • Neilep Level Member
  • ******
  • Posts: 1338
  • Thanked: 5 times
    • View Profile
Geology Question of the Week
« Reply #82 on: 11/05/2007 17:10:56 »
JimBob- no one seems to be willing to venture a guess?  Must not be many earth scientists hanging about lately?
Nice, clear photo.  The outer folded layer appears to be either quartz or quarzite (could also be calcareous?).  Can't quite make out the inner rock- even though the white specks (feldspars, clastic fragments?) seem to have no preferred orientation- I would guess sedimorphic (a new geologic term!) - metamorphosed clastic rock. Could also be some sort of subvolcanic igneous- perhaps a latite- but that may be my hard-rock bias showing.
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #83 on: 11/05/2007 17:35:25 »
Bass - Think gem minerals

I know that is a dead give-away, but as you noticed, there are not too many peopel who were wise in their carrier choice on this site.  ;D
 
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #84 on: 16/05/2007 19:11:36 »
The outer one is a PEGMATITE !! - I know that the inner part of the fold is hard to see (it is a high silicate rhyolitie) so if someone got "pegmatite" I wasn't going to carp about it. The highly crystalline nature of the pegmatite can easily be seen. The formation of the crystals on the inner sides of the fissure with crystallization evolving inward until the gap between sides is closed.

Perhaps I'll find some picts that are easier.
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #85 on: 18/05/2007 02:38:16 »
What place is considered to be the place most damaged by the largest earthquake in recorded history? It was an estimated 9.4 magnitude earthquake. 2004 Indian Ocean earthquake and tsunami was 9.0, and the one this question is about is, by most, considered much larger.
 

Offline Bass

  • Neilep Level Member
  • ******
  • Posts: 1338
  • Thanked: 5 times
    • View Profile
Geology Question of the Week
« Reply #86 on: 18/05/2007 16:51:02 »
I wasn't around for the largest, but I was in Alaska for 2nd largest in 1964. 
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #87 on: 19/05/2007 21:26:43 »
Since the Indian Ocean quake Alaska is now #3. But dang, Bass, you are almost as old as I am. The pictures of the damage on TV were in black and white!

For a hint on the question, refer to your "where in the world."
 

Offline Bass

  • Neilep Level Member
  • ******
  • Posts: 1338
  • Thanked: 5 times
    • View Profile
Geology Question of the Week
« Reply #88 on: 20/05/2007 17:30:01 »
I wasn't around for the largest, but I was in Alaska for 2nd largest in 1964. 
Sorry JimBob, I didn't phrase that very well.  I was but a young lad, and remember the b&W pictures on a very small neolithic TV.  What I meant was that I wasn't in the vicinity of this earthquake, I was way too far north- and news traveled much more slowly in Alaska during those days.
According to the USGS, Alaska is still #2.
« Last Edit: 20/05/2007 17:40:31 by Bass »
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #89 on: 28/05/2007 20:52:43 »
The Lisbon earth quake of 1755 is the one I was looking for. 35% of the population was killed in Lisbon, 10,000 in Morocco. The resultant tsunami affected southern England, Galway, Ireland and the Antilles. It is estimated by some seismologists to have been well over 9 on the Richter Scale.
 

Offline Bass

  • Neilep Level Member
  • ******
  • Posts: 1338
  • Thanked: 5 times
    • View Profile
Geology Question of the Week
« Reply #90 on: 29/05/2007 03:46:14 »
Oops- thought you were referring to the Chilean earthquake (M 9.5) in May 1960.
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #91 on: 02/06/2007 02:27:06 »



Any idea?? This is probably too easy BUT spec-tack-u-ler

 

Offline Bass

  • Neilep Level Member
  • ******
  • Posts: 1338
  • Thanked: 5 times
    • View Profile
Geology Question of the Week
« Reply #92 on: 04/06/2007 17:10:47 »
aerial photo of desert landscape with flat-lying beds.  Somewhere in Utah perhaps?  Is the white snow?  Can see a road in the upper left corner.
 

Offline JimBob

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 6564
  • Thanked: 7 times
  • Moderator
    • View Profile
Geology Question of the Week
« Reply #93 on: 10/06/2007 03:55:31 »
The satellite picture is of an area about 95 mile SW of Muscat Oman. Bass is correct about the desert landscape and sediments. But the wadi (valley) cutting across the shot is pretty obviously in a thrust fault expression. The white is possibly salt. There is a lot exposed here.
« Last Edit: 10/06/2007 03:58:52 by JimBob »
 

Offline Sarah Elizabeth

  • Jr. Member
  • **
  • Posts: 13
    • View Profile
Geology Question of the Week
« Reply #94 on: 09/01/2008 18:10:13 »
as to the red sandstone, its very common in the uk,  because we used to be on and around the equator, at around 50  degrees we were in a desert environment. the action of the sun made the rock much darker red in colour and the green has got to be copper because green marks arent left by any common tree from  the tertiary when the climate was that of a desert...the sandstone deposited in the uk has laminations if found on a grand scale.. the fact that the red sandstone has laminations ( deposited in dunes ) means that a tree could not survive in a sand environment alone.  its got to be from the element. it wouldnt be discolouring, because in sandstones the only form of discolouring is bleaching, where by the action of water removes the oxide and leaves it white !
 

Offline Sarah Elizabeth

  • Jr. Member
  • **
  • Posts: 13
    • View Profile
Geology Question of the Week
« Reply #95 on: 09/01/2008 18:12:21 »
did you know that after the big lisbon earthquake of 1755 the only building in the city found to be standing was a brothel .
 

Offline Sarah Elizabeth

  • Jr. Member
  • **
  • Posts: 13
    • View Profile
Geology Question of the Week
« Reply #96 on: 09/01/2008 18:19:50 »
to the comment about alfisol soils id like to add that soils are a completely different matter as red, iron-rich subsurface horizons are only characteristics of soil and a red desert sandstone is of that name because it is lithified sand grains cemented together by silicon or various rarer types, which have been turned red ONLY by the action of the sun. If we are talking about soils its a completely different matter !
 

Offline Sarah Elizabeth

  • Jr. Member
  • **
  • Posts: 13
    • View Profile
Geology Question of the Week
« Reply #97 on: 09/01/2008 18:29:53 »
Which river carries the highest sediment load?   .... i reckon its got to be the Amazon ! i know that it transports 2 billion tonnes of particles from the andes every year over to Africa. the Andes is the fastest growing mountain range and my favourite :) apparently, according to extremescience.com For the last century the  Amazon and Nile  have been fighting over the title for the  world's longest river. the length of them both varies across time, not sure how, but it says that the amazon carries the most amount of water.  now thats got to be something... ?
 

Offline Sarah Elizabeth

  • Jr. Member
  • **
  • Posts: 13
    • View Profile
Geology Question of the Week
« Reply #98 on: 09/01/2008 18:38:34 »
What type of rocks are these?





you know, this is a really interesting picture : the rock's awesome ! im actually going to have a guess at its formation, but id like to know where the location is...?  the rock in the middle is a hard rock but id guess its been metamorphosed , it probably was a mudstone at the bottom of a deep sea and then the calcarous stuff was laid on top,i think the fact its now on land would suggest isostasy was at work and it used to be in a warm tropical climate where the calcium carbonate limstone was laid down. it looks like it has a very high silica content but that could be metamorphosed Calcium Carbonate to make it marble- like .do you know what the rock is btw, ?
 

Offline Sarah Elizabeth

  • Jr. Member
  • **
  • Posts: 13
    • View Profile
Geology Question of the Week
« Reply #99 on: 09/01/2008 18:51:06 »
the rockies are running along the conservative plate boundary known as the san andreas fault, or the massive tear in the ground between the american plate and the pacific plate.so it is a plate boundary. theyre stil growing because the plates are active
 

The Naked Scientists Forum

Geology Question of the Week
« Reply #99 on: 09/01/2008 18:51:06 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums