Home, Sweet Home, Dream becomes Reality |
Home, Sweet Home, Dream becomes Reality |
Jan 21 2007, 08:51 PM
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#586
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
quote in reply! removed Yup. As Dubya would have said, 'He's ma man!'. I have a well worn copy of 'The Principles of Physical Geology' sitting beside my desk even now... The only flaw in his geological world-view is that he predated the serious study of impact events. Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Jan 22 2007, 07:48 AM
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#587
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Member Group: Members Posts: 688 Joined: 20-April 05 From: Sweden Member No.: 273 |
Hmmm. And then got conveniently tilted 90 degrees... ...I have my doubts about some of this. It seems a bit much to invoke gradualism *and* catastrophism on one site (I remain an acolyte of Arthur Holmes!). To me the layers look fairly horizontal and the bomb sag hypothesis is quite probable. The only other process I know of that can produce similar structures is glacial dropstones from icebergs that fall into soft bottom sediments. In both cases deformed rather than disrupted layers is quite common. tty |
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Jan 22 2007, 08:59 AM
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#588
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
To me the layers look fairly horizontal and the bomb sag hypothesis is quite probable. The only other process I know of that can produce similar structures is glacial dropstones from icebergs that fall into soft bottom sediments. In both cases deformed rather than disrupted layers is quite common. tty Hmmm... ...I wonder what a cross-section below a rock which has migrated due to freeze/thaw processes would look like? Not that I'm seriously suggesting it as an explanation here, it's just that (now that I think about it) I've never seen such a thing, and presumably a lump of stone tunneling towards freedom ought to leave some sort of trail... Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Jan 22 2007, 09:13 AM
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#589
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
'The Principles of Physical Geology' ... he predated the serious study of impact events. Bob Shaw Aye, a venerable tome indeed - required reading when I was at school. Correct me if I'm wrong but I don't think he anticipated seafloor spreading and large scale horizontal movement of continents either. |
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Jan 22 2007, 11:14 AM
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#590
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
Aye, a venerable tome indeed - required reading when I was at school. Correct me if I'm wrong but I don't think he anticipated seafloor spreading and large scale horizontal movement of continents either. Holmes was actually an early champion of Continental Drift! Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Jan 22 2007, 12:11 PM
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#591
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
Holmes was actually an early champion of Continental Drift! Bob Shaw That I had either forgotten over the last four decades or never realised in the first place! Is that in the 'Priciples' or elsewhere? I'd like to revisit if you can point me in the right direction. Sounds like a trip to the library is called for. In my one-year encounter with the geology department at St. Andrews continental drift for the Earth and impact cratering for the Moon were both strictly off the menu, leaving me with the frustrating impression that geologists in general were in perverse denial about the most significant (and visibly obvious) morphological processes on both worlds. |
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Jan 22 2007, 01:19 PM
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#592
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
That I had either forgotten over the last four decades or never realised in the first place! Is that in the 'Priciples' or elsewhere? See Helvick's post #585 above! Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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Jan 22 2007, 01:50 PM
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#593
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
See Helvick's post #585 above! Bob Shaw Thanks Bob and Helvick. Everyone else - sorry for the unmartian diversion. Off to the library I go (or maybe the second hand bookshop) to re-learn what I must have unlearned in St. Andrews. An unexpectedly fruitful outcome from my feeble attempt at humour . . . Sheer luck Holmes! |
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Jan 24 2007, 12:35 AM
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#594
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Member Group: Members Posts: 866 Joined: 15-March 05 From: Santa Cruz, CA Member No.: 196 |
Hmmm... ...I wonder what a cross-section below a rock which has migrated due to freeze/thaw processes would look like? Not that I'm seriously suggesting it as an explanation here, it's just that (now that I think about it) I've never seen such a thing, and presumably a lump of stone tunneling towards freedom ought to leave some sort of trail... Bob Shaw er yeah, one would similarly wonder if impact ejecta could give a similar appearance if it fell onto a muddy plain... no volcanic origin necessary... just a terrestrial rock, perhaps by chance even originally volcanic, but sunk into the soft layered sediments completely via non-volcanic (or even as thrown about in this thread, freeze/thaw or glacier) processes. how could we tell the difference? |
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Jan 24 2007, 03:29 AM
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#595
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Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
but sunk into the soft layered sediments completely via non-volcanic (or even as thrown about in this thread, freeze/thaw or glacier) processes. ....or even as a byproduct of mass wasting from a steep cliff or hillside; bounce, bounce, bounce, thud! note the carefully culled quote -------------------- If Occam had heard my theory, things would be very different now.
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Jan 24 2007, 06:22 AM
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#596
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Senior Member Group: Members Posts: 2228 Joined: 1-December 04 From: Marble Falls, Texas, USA Member No.: 116 |
In the end, this thing can be explained using a number of familiar earthly processes if we only consider the physical appearance in the images. I can't remember where, but I recall some official mention of spectrometry supporting a classical volcanic composition over the entire thickness of the stack here. Though not definitive, that would seem to tilt favorably toward volcanic physical processes being involved in the origin of these rocks. The aeolian reworking of the upper section really threw we for a while, but I am beginning to see that there are a number of ways to look at the information we have.
The sub-discussion of some of the founding concepts of modern geology (and indeed, many other sciences), reminded me of the "standing on shoulders" concept that is often mentioned when major advances in science are discussed. Hutton's gradualism, Lyell's uniformitarianism, Bretz's catastrophism...you can argue over who first proposed some of those concepts, but in the end it all depends on many people collaborating over time. That is what I find so interesting about our current situation. We find ourselves exploring an alien world, trying to imagine it's origin and history, and realizing that the philosophy of science that we created on our world can be extended to others. We are here collaborating. Could life be better? -------------------- ...Tom
I'm not a Space Fan, I'm a Space Exploration Enthusiast. |
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Jan 25 2007, 08:56 PM
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#597
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Junior Member Group: Members Posts: 50 Joined: 7-July 06 From: Selden, NY Member No.: 960 |
I can't remember where, but I recall some official mention of spectrometry supporting a classical volcanic composition over the entire thickness of the stack here. Though not definitive, that would seem to tilt favorably toward volcanic physical processes being involved in the origin of these rocks. The Mini-TES work that Steve Ruff has done indicates that Home Plate has a large component of volcanic glass, supporting the volcanic hypothesis. |
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