Uncle Siphuncle Posted February 6, 2014 Share Posted February 6, 2014 I was exploring new areas in the Balcones Fault Zone of Texas recently, concentrating on Campanian aged sediments. While investigating an area of potential, I noticed that the lithology of the rock was markedly different from what was mapped there. Soon I began finding ammonites, nautiloids, bivalves, and echinoids that suggested a different formation not just because of their species, but because of their mode of preservation. So the moral of the story today is to NOT take everything you see on a geological map at face value. Any number of factors can explain discrepancies: -Erosion -Small scale faulting -Map scale -More thorough knowledge of an area since the map was made Interestingly, I could see that the bedrock had been core sampled years back in several areas along the exposure. In summary, maps will get you in the ball park, but there is no substitute for hands on knowledge of fauna and lithology that occur in other formations in the vicinity. 1 Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted February 6, 2014 Author Share Posted February 6, 2014 More Pachydiscus Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted February 6, 2014 Author Share Posted February 6, 2014 Placenticeras Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted February 6, 2014 Author Share Posted February 6, 2014 Pachydiscus, Baculites, Eutrephoceras Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted February 6, 2014 Author Share Posted February 6, 2014 Petalobrissus echinoid Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
FossilDudeCO Posted February 6, 2014 Share Posted February 6, 2014 nice finds dan, very jealous. Texas isn't that far..... Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted February 6, 2014 Author Share Posted February 6, 2014 Perhaps a very ratty but rare Cardiaster Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Auspex Posted February 6, 2014 Share Posted February 6, 2014 You practice the "William Smith school of Geology".... So many of the maps published have had but cursory ground-truthing. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
sixgill pete Posted February 6, 2014 Share Posted February 6, 2014 Very nice Dan, I really like that Petalobrissus Echinoid. Bulldozers and dirt Bulldozers and dirt behind the trailer, my desert Them red clay piles are heaven on earth I get my rocks off, bulldozers and dirt Patterson Hood; Drive-By Truckers May 2016 May 2012 Aug 2013, May 2016, Apr 2020 Oct 2022 Link to comment Share on other sites More sharing options...
PFOOLEY Posted February 6, 2014 Share Posted February 6, 2014 (edited) You would be the person to discover a discrepancy. You are motivated, and therefore...your spoils. Excellent discoveries Mr. Woehr...you find some ridiculous specimens. Your baculite is fantastic! Be sure to post what you find "over that next hill". P.S. Don't take it out on the maps...they only know what they know. Edited February 6, 2014 by PFOOLEY "I am glad I shall never be young without wild country to be young in. Of what avail are forty freedoms without a blank spot on the map?" ~Aldo Leopold (1887-1948) New Mexico Museum of Natural History Bulletins Link to comment Share on other sites More sharing options...
Plantguy Posted February 6, 2014 Share Posted February 6, 2014 Hey Dan, I remember a senior mapping project in the desert that involved unauthorized beverages many moons ago. I will tell you there was a bit of variety in the maps produced in those senior papers from that trip. You need to buy a drone to do your fossil surveying first! Just dont go above I think its 400 ft or the FAA will be after you. Regards,Chris Link to comment Share on other sites More sharing options...
2ynpigo Posted February 6, 2014 Share Posted February 6, 2014 It's not that uncommon for quadrangles to contain mapping errors. Usually the areas mapped incorrectly are not large in extent. The field mappers usually have but short times to map entire 7.5 minute quadrangles, so some mistakes are almost certain to occur. I know of several maps done by the USGS and local university geologists in my area that have mistakes. But again, the majority of the mapped areas are well done. Link to comment Share on other sites More sharing options...
Missourian Posted February 6, 2014 Share Posted February 6, 2014 (edited) Nice ammos and echs. I have a geo map that shows a normal fault with displacement of strata on both sides. When I checked it out for myself, the 'fault' turned out to be a couple car-sized blocks of limestone that slid about 40 feet down a steep slope. In another spot, they also interpreted the middle of one limestone formation as the top of the one below it. There are a few nearby outcrops that would have provided context. But still, overall, the map is excellent. Edited February 6, 2014 by Missourian Context is critical. Link to comment Share on other sites More sharing options...
jpc Posted February 6, 2014 Share Posted February 6, 2014 I've actually found a hill that was just plain missing from a topo map once. Topos are usually amazingly accurate. At least in the lower 48 Link to comment Share on other sites More sharing options...
Ludwigia Posted February 6, 2014 Share Posted February 6, 2014 Well anyway, this post just goes to show that it helps to know your stuff. Nice finds, Dan! Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
wfrr Posted February 6, 2014 Share Posted February 6, 2014 My most coveted spots are the ones that don't match up with the GEO map. It still pays to explore and verify. rr Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted February 6, 2014 Author Share Posted February 6, 2014 sounds as if many of you veterans have confirmed this situation for yourselves! Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Auspex Posted February 6, 2014 Share Posted February 6, 2014 "Trust, but verify." tracer "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
erose Posted February 7, 2014 Share Posted February 7, 2014 "Trust, but verify." tracer EXactly. Link to comment Share on other sites More sharing options...
Wrangellian Posted February 7, 2014 Share Posted February 7, 2014 I'm sure none of my local maps are very accurate, so I need to reply on my ground experience, but more accurate ones out there that I have yet to get my hands on. Little outcrops keep turning up that were previously unmapped. Also with the forest cover in this part of the world it's a wonder how there is any detail at all. Dan, what formation/age do your fossils indicate that wasn't previously mapped there? I like that baculite, too. Link to comment Share on other sites More sharing options...
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