On 2021-10-13, Don Y <blockedofcourse@foo.invalid> wrote:> On 10/13/2021 12:52 AM, Tom Gardner wrote: >> On 13/10/21 05:01, Don Y wrote: >>> On 10/12/2021 3:46 PM, Tom Gardner wrote: >>>> On 12/10/21 22:59, Don Y wrote: >>>>> On 10/12/2021 2:28 PM, Martin Brown wrote: >>>>>> On 12/10/2021 20:44, Don Y wrote: >>>>>>> On 10/12/2021 9:23 AM, Joe Gwinn wrote: >>>>>>>> On Tue, 12 Oct 2021 14:15:33 +0100, Martin Brown >>>>>>>> <'''newspam'''@nonad.co.uk> wrote: >>>>>>>> >>>>>>>>> On 12/10/2021 12:53, Don Y wrote: >>>>>>>>>> I caught the tail end (last 2-3 minutes) of a TV show which depicted >>>>>>>>>> a couple of guys hunting for gold deposits with the sorts of metal >>>>>>>>>> detectors you'd look for trinkets on a sandy beach. >>>>>>>>>> >>>>>>>>>> And, apparently, *finding* same! (gold just lying around in >>>>>>>>>> surface rock outcroppings? who'd guessed!) >>>>>> >>>>>> They must have known enough about the geology to be in about the right >>>>>> place then. >>>>> >>>>> No doubt! I was surprised that it would be that near the surface. >>>>> And, to wonder how they *knew* it would be there! >>>>> >>>>> (Did someone, someday, just happen to look down and say, "My! There's >>>>> a gold nugget by my left foot!" And, thereafter, the area known for >>>>> "gold just lying around"? If so, why is there *still* any left to >>>>> be found -- if it was common knowledge!) >>>> >>>> According to school geography lessons, the importance >>>> of Kiirunavaara was discovered when someone found his >>>> steel knife was attracted to the ground. >>>> >>>> I've never understood why gold (and similar) elements, >>>> which were produced in supernovae, aren't evenly >>>> distributed lone atoms. >>> >>> Why aren't celestial bodies perfectly round (oblate) orbs? >> >> They are good approximations. >> >>> Why Les Alpes and The Mariana Trench? >> >> Plate tectonics. > > Why are there plates? That suggests some nonuniformity in composition.Yeah, on the outside the magma freezes. -- Jasen.
Metal detectors
Started by ●October 12, 2021
Reply by ●October 13, 20212021-10-13
Reply by ●October 13, 20212021-10-13
On 10/13/2021 1:42 AM, Jeroen Belleman wrote:>> He, OTOH, *expects* to find them so just keeps looking until he >> finds them. >> >> <shrug> Makes some sort of sense. Personally, *I've* never found one! >> (but, I don't sit in fields of clover TRYING TO!) > > When my wife tells me she sees some, I fully expect to find > them, but I still don't. Not that I'm short of four-leaved > clovers, thanks to my spouse. People must think I'm > superstitious sometimes, with all these funny clovers. > I'm not. I just love my wife.As idiosyncrasies go, it's relatively harmless. Collecting stray *bobcats*, not so much...
Reply by ●October 13, 20212021-10-13
On Wednesday, 13 October 2021 at 19:35:48 UTC+11, Don Y wrote:> On 10/13/2021 12:52 AM, Tom Gardner wrote: > > On 13/10/21 05:01, Don Y wrote: > >> On 10/12/2021 3:46 PM, Tom Gardner wrote: > >>> On 12/10/21 22:59, Don Y wrote: > >>>> On 10/12/2021 2:28 PM, Martin Brown wrote: > >>>>> On 12/10/2021 20:44, Don Y wrote: > >>>>>> On 10/12/2021 9:23 AM, Joe Gwinn wrote: > >>>>>>> On Tue, 12 Oct 2021 14:15:33 +0100, Martin Brown > >>>>>>> <'''newspam'''@nonad.co.uk> wrote: > >>>>>>> > >>>>>>>> On 12/10/2021 12:53, Don Y wrote: > >>>>>>>>> I caught the tail end (last 2-3 minutes) of a TV show which depicted > >>>>>>>>> a couple of guys hunting for gold deposits with the sorts of metal > >>>>>>>>> detectors you'd look for trinkets on a sandy beach. > >>>>>>>>> > >>>>>>>>> And, apparently, *finding* same! (gold just lying around in > >>>>>>>>> surface rock outcroppings? who'd guessed!) > >>>>> > >>>>> They must have known enough about the geology to be in about the right > >>>>> place then. > >>>> > >>>> No doubt! I was surprised that it would be that near the surface. > >>>> And, to wonder how they *knew* it would be there! > >>>> > >>>> (Did someone, someday, just happen to look down and say, "My! There's > >>>> a gold nugget by my left foot!" And, thereafter, the area known for > >>>> "gold just lying around"? If so, why is there *still* any left to > >>>> be found -- if it was common knowledge!) > >>> > >>> According to school geography lessons, the importance > >>> of Kiirunavaara was discovered when someone found his > >>> steel knife was attracted to the ground. > >>> > >>> I've never understood why gold (and similar) elements, > >>> which were produced in supernovae, aren't evenly > >>> distributed lone atoms. > >> > >> Why aren't celestial bodies perfectly round (oblate) orbs? > > > > They are good approximations. > > > >> Why Les Alpes and The Mariana Trench? > > > > Plate tectonics. > Why are there plates? That suggests some nonuniformity in composition.Earth's crust is a minor component of the planet: https://www.wowreally.blog/2007/01/earths-crust-thinner-than-apples-skin.html From the bottom of Marianas to the top of Everest is ~ 19.9km vs Earth's radius ~6371km gives ~0.3% - surface features are negligible... -- Cheers, Chris
Reply by ●October 13, 20212021-10-13
On 10/13/2021 3:29 PM, Chris wrote:> On Wednesday, 13 October 2021 at 19:35:48 UTC+11, Don Y wrote: >> On 10/13/2021 12:52 AM, Tom Gardner wrote: >>> On 13/10/21 05:01, Don Y wrote: >>>> On 10/12/2021 3:46 PM, Tom Gardner wrote: >>>>> On 12/10/21 22:59, Don Y wrote: >>>>>> On 10/12/2021 2:28 PM, Martin Brown wrote: >>>>>>> On 12/10/2021 20:44, Don Y wrote: >>>>>>>> On 10/12/2021 9:23 AM, Joe Gwinn wrote: >>>>>>>>> On Tue, 12 Oct 2021 14:15:33 +0100, Martin Brown >>>>>>>>> <'''newspam'''@nonad.co.uk> wrote: >>>>>>>>> >>>>>>>>>> On 12/10/2021 12:53, Don Y wrote: >>>>>>>>>>> I caught the tail end (last 2-3 minutes) of a TV show which depicted >>>>>>>>>>> a couple of guys hunting for gold deposits with the sorts of metal >>>>>>>>>>> detectors you'd look for trinkets on a sandy beach. >>>>>>>>>>> >>>>>>>>>>> And, apparently, *finding* same! (gold just lying around in >>>>>>>>>>> surface rock outcroppings? who'd guessed!) >>>>>>> >>>>>>> They must have known enough about the geology to be in about the right >>>>>>> place then. >>>>>> >>>>>> No doubt! I was surprised that it would be that near the surface. >>>>>> And, to wonder how they *knew* it would be there! >>>>>> >>>>>> (Did someone, someday, just happen to look down and say, "My! There's >>>>>> a gold nugget by my left foot!" And, thereafter, the area known for >>>>>> "gold just lying around"? If so, why is there *still* any left to >>>>>> be found -- if it was common knowledge!) >>>>> >>>>> According to school geography lessons, the importance >>>>> of Kiirunavaara was discovered when someone found his >>>>> steel knife was attracted to the ground. >>>>> >>>>> I've never understood why gold (and similar) elements, >>>>> which were produced in supernovae, aren't evenly >>>>> distributed lone atoms. >>>> >>>> Why aren't celestial bodies perfectly round (oblate) orbs? >>> >>> They are good approximations. >>> >>>> Why Les Alpes and The Mariana Trench? >>> >>> Plate tectonics. >> Why are there plates? That suggests some nonuniformity in composition. > > Earth's crust is a minor component of the planet: https://www.wowreally.blog/2007/01/earths-crust-thinner-than-apples-skin.html > > From the bottom of Marianas to the top of Everest is ~ 19.9km vs Earth's radius ~6371km gives ~0.3% - surface features are negligible...Place a drop of water in a weightless environment. Tell me how much variation their is in its shape...
Reply by ●October 13, 20212021-10-13
On 14/10/21 10:27 am, Don Y wrote:> On 10/13/2021 3:29 PM, Chris wrote: >> On Wednesday, 13 October 2021 at 19:35:48 UTC+11, Don Y wrote: >>> On 10/13/2021 12:52 AM, Tom Gardner wrote: >>>> On 13/10/21 05:01, Don Y wrote: >>>>> On 10/12/2021 3:46 PM, Tom Gardner wrote: >>>>>> On 12/10/21 22:59, Don Y wrote: >>>>>>> On 10/12/2021 2:28 PM, Martin Brown wrote: >>>>>>>> On 12/10/2021 20:44, Don Y wrote: >>>>>>>>> On 10/12/2021 9:23 AM, Joe Gwinn wrote: >>>>>>>>>> On Tue, 12 Oct 2021 14:15:33 +0100, Martin Brown >>>>>>>>>> <'''newspam'''@nonad.co.uk> wrote: >>>>>>>>>> >>>>>>>>>>> On 12/10/2021 12:53, Don Y wrote: >>>>>>>>>>>> I caught the tail end (last 2-3 minutes) of a TV show which >>>>>>>>>>>> depicted >>>>>>>>>>>> a couple of guys hunting for gold deposits with the sorts of >>>>>>>>>>>> metal >>>>>>>>>>>> detectors you'd look for trinkets on a sandy beach. >>>>>>>>>>>> >>>>>>>>>>>> And, apparently, *finding* same! (gold just lying around in >>>>>>>>>>>> surface rock outcroppings? who'd guessed!) >>>>>>>> >>>>>>>> They must have known enough about the geology to be in about the >>>>>>>> right >>>>>>>> place then. >>>>>>> >>>>>>> No doubt! I was surprised that it would be that near the surface. >>>>>>> And, to wonder how they *knew* it would be there! >>>>>>> >>>>>>> (Did someone, someday, just happen to look down and say, "My! >>>>>>> There's >>>>>>> a gold nugget by my left foot!" And, thereafter, the area known for >>>>>>> "gold just lying around"? If so, why is there *still* any left to >>>>>>> be found -- if it was common knowledge!) >>>>>> >>>>>> According to school geography lessons, the importance >>>>>> of Kiirunavaara was discovered when someone found his >>>>>> steel knife was attracted to the ground. >>>>>> >>>>>> I've never understood why gold (and similar) elements, >>>>>> which were produced in supernovae, aren't evenly >>>>>> distributed lone atoms. >>>>> >>>>> Why aren't celestial bodies perfectly round (oblate) orbs? >>>> >>>> They are good approximations. >>>> >>>>> Why Les Alpes and The Mariana Trench? >>>> >>>> Plate tectonics. >>> Why are there plates? That suggests some nonuniformity in composition. >> >> Earth's crust is a minor component of the planet: >> https://www.wowreally.blog/2007/01/earths-crust-thinner-than-apples-skin.html >> >> >> From the bottom of Marianas to the top of Everest is ~ 19.9km vs >> Earth's radius ~6371km gives ~0.3% - surface features are negligible... > > Place a drop of water in a weightless environment. Tell me how much > variation their is in its shape...Bad analogy. Try a drop of molten lead, encrusted with oxides. You have played with melted metal on a bunsen burner as a child, I expect? Do you recall seeing the oxide crust? Did you stir the metal and see how it forms ridges where agglomerated regions of oxide collide? That's like the earth's crust. Earth is smoother than a billiard ball, to scale. Clifford Heath.
Reply by ●October 14, 20212021-10-14
On Wednesday, October 13, 2021 at 7:35:48 PM UTC+11, Don Y wrote:> On 10/13/2021 12:52 AM, Tom Gardner wrote: > > On 13/10/21 05:01, Don Y wrote: > >> On 10/12/2021 3:46 PM, Tom Gardner wrote: > >>> On 12/10/21 22:59, Don Y wrote: > >>>> On 10/12/2021 2:28 PM, Martin Brown wrote: > >>>>> On 12/10/2021 20:44, Don Y wrote: > >>>>>> On 10/12/2021 9:23 AM, Joe Gwinn wrote: > >>>>>>> On Tue, 12 Oct 2021 14:15:33 +0100, Martin Brown > >>>>>>> <'''newspam'''@nonad.co.uk> wrote: > >>>>>>> > >>>>>>>> On 12/10/2021 12:53, Don Y wrote: > >>>>>>>>> I caught the tail end (last 2-3 minutes) of a TV show which depicted > >>>>>>>>> a couple of guys hunting for gold deposits with the sorts of metal > >>>>>>>>> detectors you'd look for trinkets on a sandy beach. > >>>>>>>>> > >>>>>>>>> And, apparently, *finding* same! (gold just lying around in > >>>>>>>>> surface rock outcroppings? who'd guessed!) > >>>>> > >>>>> They must have known enough about the geology to be in about the right > >>>>> place then. > >>>> > >>>> No doubt! I was surprised that it would be that near the surface. > >>>> And, to wonder how they *knew* it would be there! > >>>> > >>>> (Did someone, someday, just happen to look down and say, "My! There's > >>>> a gold nugget by my left foot!" And, thereafter, the area known for > >>>> "gold just lying around"? If so, why is there *still* any left to > >>>> be found -- if it was common knowledge!) > >>> > >>> According to school geography lessons, the importance > >>> of Kiirunavaara was discovered when someone found his > >>> steel knife was attracted to the ground. > >>> > >>> I've never understood why gold (and similar) elements, > >>> which were produced in supernovae, aren't evenly > >>> distributed lone atoms. > >> > >> Why aren't celestial bodies perfectly round (oblate) orbs? > > > > They are good approximations. > > > >> Why Les Alpes and The Mariana Trench? > > > > Plate tectonics. > > Why are there plates? That suggests some nonuniformity in composition.There's a thermal gradient from the centre of the earth - which seems to be at 6000 degrees Celsius - to the top of the atmosphere which is at about -18 Celcius. There's also a pressure gradient, which means that the inner core is solid, even though it is very hot. Most of the volume is liquid, circulated by convention currents. The mantle is solid, but it isn't all that homogenous, and the continental plates are chunks of lighter rock that float higher than than the denser stuff under the oceans. The bottoms of the continental plates get to exchange elements with the circulating liquid rock in the molten shell above the solid core, and the solubility of particular atoms in sold rock isn't the same as their solubility in molten rock, so you get differences in composition, and those differences change with the local melting point (which changes with differences in composition). It's complicated, and we can't drill down to the bottom of the continental plates. We haven't even got to the https://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuity yet, and that's just the discontinuity between the outer crust and the most plastic - but still frozen - inner crust. -- Bill Sloman, Sydney
Reply by ●October 14, 20212021-10-14
On a sunny day (Tue, 12 Oct 2021 04:53:31 -0700) it happened Don Y <blockedofcourse@foo.invalid> wrote in <sk3t02$csg$1@dont-email.me>:>I caught the tail end (last 2-3 minutes) of a TV show which depicted >a couple of guys hunting for gold deposits with the sorts of metal >detectors you'd look for trinkets on a sandy beach. > >And, apparently, *finding* same! (gold just lying around in >surface rock outcroppings? who'd guessed!)Obvious, gold is heavy, here in the northern hemisphere it is burried deep, while In Australia it sinks to the surface.
Reply by ●October 14, 20212021-10-14
On Thursday, October 14, 2021 at 4:40:00 PM UTC+11, Ferry wrote:> On a sunny day (Tue, 12 Oct 2021 04:53:31 -0700) it happened Don Y > <blocked...@foo.invalid> wrote in <sk3t02$csg$1...@dont-email.me>: > >I caught the tail end (last 2-3 minutes) of a TV show which depicted > >a couple of guys hunting for gold deposits with the sorts of metal > >detectors you'd look for trinkets on a sandy beach. > > > >And, apparently, *finding* same! (gold just lying around in > >surface rock outcroppings? who'd guessed!) > Obvious, gold is heavy, here in the northern hemisphere it is buried deep, > while In Australia it sinks to the surface.Odd how it did the same thing in California. -- Bill Sloman, Sydney
Reply by ●October 14, 20212021-10-14
On 14/10/21 07:11, Anthony William Sloman wrote:> On Thursday, October 14, 2021 at 4:40:00 PM UTC+11, Ferry wrote: >> On a sunny day (Tue, 12 Oct 2021 04:53:31 -0700) it happened Don Y >> <blocked...@foo.invalid> wrote in <sk3t02$csg$1...@dont-email.me>: >>> I caught the tail end (last 2-3 minutes) of a TV show which depicted >>> a couple of guys hunting for gold deposits with the sorts of metal >>> detectors you'd look for trinkets on a sandy beach. >>> >>> And, apparently, *finding* same! (gold just lying around in >>> surface rock outcroppings? who'd guessed!) >> Obvious, gold is heavy, here in the northern hemisphere it is buried deep, >> while In Australia it sinks to the surface. > > Odd how it did the same thing in California. >We are always being told that California is /odd/. Clearly, since California is at the edge of the world, that's where centrifugal forces are strongest. Ditto Yukon.
Reply by ●October 14, 20212021-10-14
On Thursday, October 14, 2021 at 7:09:23 PM UTC+11, Tom Gardner wrote:> On 14/10/21 07:11, Anthony William Sloman wrote: > > On Thursday, October 14, 2021 at 4:40:00 PM UTC+11, Ferry wrote: > >> On a sunny day (Tue, 12 Oct 2021 04:53:31 -0700) it happened Don Y > >> <blocked...@foo.invalid> wrote in <sk3t02$csg$1...@dont-email.me>: > >>> I caught the tail end (last 2-3 minutes) of a TV show which depicted > >>> a couple of guys hunting for gold deposits with the sorts of metal > >>> detectors you'd look for trinkets on a sandy beach. > >>> > >>> And, apparently, *finding* same! (gold just lying around in > >>> surface rock outcroppings? who'd guessed!) > >> Obvious, gold is heavy, here in the northern hemisphere it is buried deep, > >> while In Australia it sinks to the surface. > > > > Odd how it did the same thing in California. > > > We are always being told that California is /odd/. > > Clearly, since California is at the edge of the world, > that's where centrifugal forces are strongest. Ditto > Yukon.So how come John Larkin and Sarah Palin weren't slung off into space? Life would be so much nicer if this had happened. Of course Tasmania is equally peripheral, and I managed to grow up there. -- Bill Sloman, Sydney
