Re: Estimating water quality


"Carsten Troelsgaard" <carsten.troelsgaardNOSPAM@xxxxxxx> wrote in message
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" George" <George@xxxxxxxxxxxxxxxxxxxxx> skrev i en meddelelse
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Maybe in Siberia or Antarctica. lol. Seriously, though. One thing
you
can do is try to find the source of the springs (sinkholes

I tried to photograph what's thought to be a 'sinkhole' (so termed in
lack
of other reasonable explanation. Alternative explanation: ice-lump left
over
melting late) - I walk uphill, pass it on it's right, and shoot it from
above:
It's posted to extend Jo's karst expertize into soft chalk

up is south
http://www.sitecenter.dk/geocsite/geologicamshots/view.nhtml?profile=geologicamshots&UID=10088

http://www.sitecenter.dk/geocsite/geologicamshots/view.nhtml?profile=geologicamshots&UID=10090

Looking at the depression toward east
http://www.sitecenter.dk/geocsite/geologicamshots/view.nhtml?profile=geologicamshots&UID=10091

The depression is in the lower right
http://www.sitecenter.dk/geocsite/geologicamshots/view.nhtml?profile=geologicamshots&UID=10092

The bridge is visible on the air-photo. The spring is off to the right.
The
spring has a modest ~25 m run from the foot of the hill to the river.
Other smaller sinkholes are noticable in the forrest, but only as
depressions with no visible fracture or water draining into it.

If you browse the neighbourhood on the air-photo (or zoom out), the
closest
potential polluter is off toward south west, or right south - both has
topographic high divides in between their location and the springs. The
valley itself is achtually quite low topography, so it may attract
water
from far away - this must be be the rational explanation.

Carsten

That does look to be a shallow, closed sinkhole. However, I was thinking
more along the lines of sinkholes further upgradient, such as in the
forest on the hill behind the spring (the one the spring is emanating
from) and beyond.

Further uphill there's nothing but small but more abrupt depressions. But
I'll have it in mind. I've come here often and ought to recollect
something, but sometimes it takes the right expectations.

As for the topographic divides, I think Jo will concur when I say that
karst is notorious for ignoring topographic divides.

I'm trying to get the hang of what it means in practice ;o/

It means that caves often do the unexpected.

If there are fractures or other planes of weakness in the bedrock, the
water (and anything in it) will get through.

That /is/ the official explanation here as the source of the wells

It works for me.

There are quite a few here in Kentucky that do that, especially during
high water. Mammoth cave here in Kentucky, for instance (which is
actually composed of several cave systems) is notorious for diving right
through topographic divides and linking up with other caves. It was the
discovery of this fact that allowed it to be linked to other caves in
the area. While I am not saying that this is the case with your spring,
I wouldn't discount it. The only way to know for sure is to conduct a
proper dye trace in order to delineate the extent of the karst system.
And that would likely take cooperation/permission with proper officials.
You certainly don't want a neighbor's pond, spring, or water well to
turn up florescent green unexpectedly. Not an enjoyable prospect.

I'm pretty sure that there's no known 'entrance' to the conduites

Interesting. Sounds like a spring developed in a fracture system, as you
indicated above. Sounds youthful as well. Most of the caves around here
are quite old. If that is the case, it may be hard to say where the water
is originating from without doing fracture trace analysis, and or a dye
trace.

But a thorough sinkhole survey at this point, might be in order. That's
what I'd do. In fact, when I looked at the aerial photo you included, I
see what appears to be at least two possible sinkholes in the forest -
one just to the southeast of the spring resurgence (the indentation in
the forest cover near the bottom of the image to the right of center
bottom) nearly in a straight line with the spring channel,

I'll have a look. I think that it's a small mount with a couple of
decidious trees, but, we'll see

Hard to say without seeing it first-hand, or without a topo map.

and one near the right center of the image (the indentation in the
forest cover). They may or may not be sinkholes, but might also be
worth investigating.

I think it's nothing but a change of the canopy

Change in canopy can mean a bedrock distubance (or dead trees, or both).
Hard to say from the aerial photo alone.

There may be others there was well that are not easy to see from the
air.

The one I tried to photograph is on the air-photo
The straight front of the forrest has an indentation (lower left),
extending the meadow up the hillside. In the upper right corner is the
sinkhole. On one of my pics I shoot with the trail in the background of
the picture, across the hole toward east.

http://www.sitecenter.dk/geocsite/geologicamshots/view.nhtml?profile=geologicamshots&UID=10091

Notice the 'forrest' has gone since the air-photo was taken - had a
couple of windy years

I'll assume that any surficial expression of caves has been ruined or
modified by glacial ice - and to some extend ice-pressure may have worked
in depth. 10.000 years for making a new karst-landscape is no time.

Interesting. How about the possibility that it is a buried karst, one that
got filled up with glacial debris, and so the water is flowing through the
rubble-filled system? That would explain why there is no noticible conduit
(although one may actually exist). Are there glacial cobbles in the spring
stream before it intersects the larger stream? I thihk I remember you
saying to Jo that the bedrock there was chalk. Is that correct?

Just be glad that you don't have to deal with these:

http://tinyurl.com/nglom

Watch where you go.

Watch where you build as well!

That is a beautiful area, by the way.

Yep, just all too little of it. I spent my childhood vacations 200 m
northwest of the upper left corner. Now it's a good 50 km bicycle-ride in
weekends. The official danish 4. July celebration takes place right above
the first spring 1 or 2 km further west.


Carsten

Sounds nice.

George


.

Relevant Pages

  • Re: Estimating water quality
    ... Alternative explanation: ice-lump left over ... Looking at the depression toward east ... Other smaller sinkholes are noticable in the forrest, ... depressions with no visible fracture or water draining into it. ...
    (sci.geo.geology)
  • Re: Estimating water quality
    ... Other smaller sinkholes are noticable in the forrest, ... depressions with no visible fracture or water draining into it. ... As for the topographic divides, I think Jo will concur when I say ... Mammoth cave here in Kentucky, ...
    (sci.geo.geology)
  • Re: Estimating water quality
    ... Other smaller sinkholes are noticable in the forrest, ... depressions with no visible fracture or water draining into it. ... It means that caves often do the unexpected. ...
    (sci.geo.geology)
  • Re: Estimating water quality
    ... Other smaller sinkholes are noticable in the forrest, ... depressions with no visible fracture or water draining into it. ... through topographic divides and linking up with other caves. ...
    (sci.geo.geology)
  • Re: Estimating water quality
    ... the forest - one just to the southeast of the spring resurgence (the ... And I thought that it could have been this beech-grown mount ... They may or may not be sinkholes, ... camera sail through the 'channel') - awful lot of misses and a few gems ...
    (sci.geo.geology)
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