This is an archive of CompuServe forum messages from 1985 to 1995, as saved in transcripts by John Foust.
Search Results (977 messages)
Hi, Kamron– >> Your only out is that Antarctica is not in motion and the Mid Ocean Ridge is expanding around it. I dimly recall a mention that that is roughly what is happening. I have spoken of Antarctica moving away from Australia and sideways past Africa, but that is…
Hi, Lanny– Argh, you had to ask about taxes. Not only must I do that almost from scratch, with extra confusion because my employer withheld tax for the wrong state, but my first issue of UV Waves (Fluor. Min. Soc. newsletter) is due at the printers that same day. With…
Hi, Kamron– I guess you are talking about those rises bracketing the Panama Deep and maybe the Galapagos Islands. Is it clear they are really as mesa-like as they appear on the map? Let a number of volcanoes like the big island of Hawaii all form in a region near…
Hi, Kamron– Yes, the deeper the core sample the better for understanding them of course. I'll check the article again when I get moved and organized and see if it mentions a depth of sampling that I overlooked. But until someone provides a strong identification, I figure they are neither…
Hi, Jon– I would be a bit stirred up if Mauna Loa 'spit' rocks forcefully or a lot stirred up if it brought up continental rock. I have heard mention of volcanoes bringing up presumed mantle rock fragments, but do not recall what type of volcano that was. I have…
Hi, Kamron– I am packing for my imminent move back to Calif., thus my Scientific Americans are no longer arranged for a quick search of favorite articles. If my memory gets jogged about what else was in the same article, I may suddenly zero in on it; if not, remember…
Hi, Bill– The Fluorescent Mineral Society is working on a fluorescent color standard. Is this what Ron is involved with? If not, we need to bring certain people together… –Doug
Hi, Kamron– >> I agree that a unified motion is what is stated but you cannot have a unified motion into and out of a large arc. Says who? All it needs is some subduction where the plate is not moving quite perpendicular to the subduction boundary. >> This is…
Hi, Kamron– >> We predicted if this motion was present then the South East ridge would shift to the South East. This is proved by the bow in the shift faults to the SE if there is plate motion…see the bow showing progression of the location of the shift fault…
Hi, Howard– >> Most of the kaolinite I run into doesn't fluoresce at all, at least not in long-wave. For typical fluorescences it is very sensitive to locale and impurities. Calcite may fluoresce more or less any color, and most often does not fluoresce at all. There may be one…
Hi, Lanny– I look forward to April already because I will be a Calif. resident again; now I have another reason for anticipation. –Doug
Hi, Ed– I chose to speak of "roots" as the simplest way to refer to something getting pushed into the mantle as mountains were piled atop it and rebounding as the load was removed; I am not fussy about whether it is some inverted image of the mountains or a…
Hi, Kamron– >> The key here is the geological table included in the formation. If it has the layers of time then it was crust regardless of what happened in the course of time. As I said, there was one other article that remarked there was some continental material there,…
Hi, Kamron– I do not easily buy the Cook Islands Manihiki Plateau as something carved of S. America by the E. Pacific spreading ridge, because I prefer to guess S. America has been chasing that ridge since Pangaea. With subduction creating the Andes, that ridge could have moved away from…
Hi, Kamron– The article on large igneous provinces implied that they had tentatively identified many (all?) of these plateaus as basaltic masses based on seismic data; then expeditions went out to check, and verified it at Ontong-Java, Vorland (N. Atlantic), and Kerguelen. Cores or surface samples? I do not recall.…
#Internet
Message #174756
Hi, Bill– Thanks for the word on the new alt.mining.recreational newsgroup. I was able to read it using CompuServe in a manner like that described in SCIGEO.SCR in the library. It looks quite young; I found only 7 topics, where 100 would be normal for sci.geo.geology. –Doug
#Fold mountains
Message #174752
Hi, Kamron– As noted in another message, I blooped in speaking of a root as deep as the mountain is high – I should have multiplied root depths by 5 or 10, since the air/rock density ration is much greater than crust/mantle density. The Scientific American of Oct 1993 article…
Volcanic Formation Rules
Message #174748
Hi, Michael– I forgot to mention that the Scientific American of Oct. 1993 has an article on large igneous provinces, which gives both reasons and possible global consequences of huge volcanic outpourings such as the Deccan Traps I mentioned. –Doug
Hi, Howard– At last, a new fluorescent mystery! The brightest longwave-UV yellow fluorescences I know of come from scapolite (meionite, generally) from Ontario/Quebec. Wollastonite and pectolite are also notable for this. Hydrocarbon inclusions in minerals often fluoresce a bright yellowish-white, as do hydrocarbon minerals such as idrialite (which also tends…
Hi, Ed– The picture I am forming in my mind is of a great range of fold mountains (as big as the Himalayas?) forming during the collisions as/before Pangaea formed, with correspondingly great roots below them. Then, sort of like I explained to Kamron, as the tops wore down, the…
Hi, Howard– The mineralogical density difference is indeed a reason I had not mentioned why if either subducts in a collision, it will be seafloor rather than continent. Kamron and I have discussed it before, thus I sort of assumed it, but it is best to spell it out when…
Hi, Don and Jon– I remember reading about those water gaps. I cannot find the article in question at the moment, but it offered several theories about how they could have been formed. One has the river establish its course on flattish land, then uplift and differential weathering of folded…
Hi, Jon– >> My text says that Gondwanaland was assembled from continents and microcontinents very early in the Paleozoic, or even in the late Proterozoic, and stayed pretty well in one piece until it broke up in the mid-Mesozoic. In Dalziel's reconstruction in the Sci Am article, the pieces of…
Hi, Kamron– >> If the basin is only 200 million years old how can there be crustal sections out in the Pacific that have lower Paleozoic layers in them? Note in my reply to Don in this thread the discussion on the separations of Japan and New Zealand from their…
Hi, Russ– Do you have any E-addresses in that list? I expect it would be a welcome upload; I know I would find it handy in answering queries about clubs that pop up from time to time. I suspect the AFMS and/or regional FMS'es must be keeping their lists on…
Hi, Michael– Welcome to the forum! The pros who hang out here may have something to tell you if you keep watching. If we leave you thirsty for more, you might want to try the volcanoes mail-list discussed in INTERN.TXT in this forum's library. Near crustal collisions and hot spots…
Hi, Kamron– >>I see the entire continental crust as about 5 miles thick on top of a base that is more like 10 or 12 miles thick. At collision zones like the Himalayas, the crust must be at its thickest, which is more like 70 km, according to my notes.…
Hi, Jon– The author of the article (Ian W. D. Dalziel) seemed to have the strongest conviction that Antarctica was connected to Laurentia before the Cambrian; the various collisions of Laurentia (proto-N.America) with the S. American part of Gondwana seemed to be worded as more speculative, or perhaps that was…
Hi, Don– The Scientific American of Sept. 1983 has an article that says "Behind the volcanic arc the overriding plate may be extended or compressed. … If the extension of continental crust behind the arc proceeds until new oceanic crust is formed, a marginal sea will result. …just as the…
Hi, John– Thanks, I have added you to our list of rockhound club E-mail contacts. I have been collecting snailmail addresses for the clubs also; I am not sure why, maybe to allow re-establishing of contact if your E-address changes. If you have a snail-address handy for the club, may…
Hi, Kamron– >> The is no way for Antarctica to move in any direction without sliding the shift faults into an non aligned condition along some of the Mid Ocean Ridges. What specifically are referring to when you say the SW Indian ridge? The southwest Indian ridge is the spreading…
Hi, Rod– Listing the E-address in the club roster with the person's snailmail address would alert someone seeking that specific person to an alternate route. Listing the E-addresses in a separate list lets someone looking for online contacts find them more easily, and makes others more aware there is someone…
Welcome, new rockhounds!
Message #173942
Hello! We in this forum section include a wide variety of earth science interests, from professional to novice hobbyists. Here you will find collectors of minerals, fossils, rocks, and so on, with lapidaries, geologists, teachers, and more. We have been trading information and specimens. We are looking for new participants!…
Hi, Brian– Welcome to the forum/section! Why would anyone want to cross the river to gamble in Laughlin? You said the gambling was for money, not rocks, right? –Doug
Hi, Don– Thanks for the info; I was running out of ammo. –Doug
Hi, Jon– In Old Red Sandstone, I am pleased to have a name for proto-N.America + proto-Europe (Laurentia+Baltica), since I gather they were together for a long time before joining up with Pangaea. The Jan. 1995 Scientific American has a cover story proposing that Laurentia rifted away from proto-S.America ~550…
Hi, Howard– No ruckus, just an amateur (me) wondering if his understanding was outdated (it has been known to happen). –Doug
Hi, Lanny– I wrote to a Dr. Simmons in New Orleans asking about a "MINCAT" before, and never got an answer, thus sort of forgot the matter. I was hoping it was the mineral database we have been seeking. I wonder if this is the same MINCAT that you mentioned?…
Hi, Al– I obviously have no problems with meteoritophiles "meeting" here until a separate section, forum, newsgroup, or mail-list is warranted. Are those dozen or so all on CIS? While the handful of Fluor. Min. Soc. members on-line were almost all on CIS a year ago, now a number have…
Hi, Joseph– Thanks for the info; even "I dunno" can be a meaningful answer. Actually the first part about the Sikhote-Alin fall seems to have answered my real question, which should have been something like this: While meteorites big enough to retain hypersonic speeds at impact will produce craters whose…
Hi, Kamron– >> Get cars and line them up with spaces between them in neutral with the break off. now push the last one slowly forward at one inch a minute If we are moving at one inch a minute, it might take mountains on wheels to produce the big…
Hi, Kamron– Since ocean floors away from continents should collect sediments more slowly, and because the oldest, deepest seafloors will generally have had their carbonates redissolved, I expect thin layers for given geologic periods compared to continental sediments. I am not familiar with much of any river sedimentation-rate studies. Why…
Hi, Kamron– >> Looking at the point at the top of the Antarctic plate it has a spreading rate along each side..picture the triangle …it would really move sort of straight down towards the pole here as a result of the two motions leaving each of the sides motion in…
#Subduction & Ocean Basin
Message #172620
Hi, Kamron– >> Take for example the area to the west of Madagascar where the weir Ridge south of Madagascar (weird because its shift faults line up with the general direction of the ridge).. >> All three plates are converging in on them selves. That is if you take the…
Hi, Michael– Welcome to the forum! I am focused on fluorescent minerals, so that is what my sites index has (it is in ROCKDB.ARC in the library). A dump of VA entries follows. Happy hunting! –Doug Fluorite SW fluor: green LW fluor: dim green State: VA City: Amelia Court House…
Hi, Alain– The "review" that follows was written over a year ago; things (especially price) may have changed since then! After I sent a copy to Jim, he gave me some minor corrections and clarifications, still over a year ago, which I have edited in using [brackets]. My free ROCKDB.ARC…
Hi, Lanny– I had not paid attention to optical properties before, but can imagine an amateur trying to use them (I believe one can buy sets of index-of-refraction standard liquids for a quick test, though I have not priced them). I suspect no one without an XRD machine will be…
Hi, Joseph– Any idea how big a meteorite would produce these results? Is it bigger than a breadbox? –Doug
Hi, Al– Whenever I discover a few new Fluorescent Mineral Society members on-line, I send a list of FMS E-addresses to all those I know of (we are talking about maybe a dozen now). We do a lot of 2 and 3 way messaging other than that; so far no…
Hi, Kamron– First, I will respond to your message in the "All" thread, since this is a better place. Then I will respond to the your message in this thread. >> I have a major problem with the continent compressing though. I see continental collisions as resembling car collisions. A…
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