KLM Posted April 16, 2014 Share Posted April 16, 2014 Hello, my name is Kevin and I have been collecting odd fossils over the years and I wanted to get some information on a few of them. I collected this stone with maybe 20-30 sand dollars embedded through it with whole ones showing the bottom of the sand dollars on the back side. This was dug up around 2-3 miles inland from the ocean in San Diego about 30 years ago. Had it packed in the basement last 10 years. Would anyone be able to determine how old something like this is? Thanks in advance! Link to comment Share on other sites More sharing options...
Auspex Posted April 16, 2014 Share Posted April 16, 2014 They might be Dendraster ashleyi, known from the area. If so, they would be from the Pliocene, between 5 and 1.8 MYBP. I like 'em! 1 "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...
KLM Posted April 16, 2014 Author Share Posted April 16, 2014 Thanks for the reply and I had to google those answers. A great deal older than the few thousand years I was thinking they were possibly. Sounds fairly common for the San Diego area but maybe the best find for me. Link to comment Share on other sites More sharing options...
lissa318 Posted April 16, 2014 Share Posted April 16, 2014 They are very nice!!! Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted April 16, 2014 Share Posted April 16, 2014 a delightful display piece. common or not, i'd display it with pride Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
sixgill pete Posted April 16, 2014 Share Posted April 16, 2014 That is an awesome display piece. 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...
siteseer Posted April 17, 2014 Share Posted April 17, 2014 It does look like ashleyi which in that area comes from the San Diego Formation - Late Pliocene (2-3 million years old). in the Pleistocene you start seeing the modern species, D. excentricus. I have an ashleyi (San Diego Formation) from a site around Chula Vista. Jess They might be Dendraster ashleyi, known from the area. If so, they would be from the Pliocene, between 5 and 1.8 MYBP. I like 'em! Link to comment Share on other sites More sharing options...
RJB Posted April 17, 2014 Share Posted April 17, 2014 Very cool rock ya got there! Ever think about prepping it out? RB Link to comment Share on other sites More sharing options...
KLM Posted April 17, 2014 Author Share Posted April 17, 2014 RJB - If you mean cleaning it up yes. I'm not sure how to do this myself. Looks like compressed sand and I thought I could use a toothbrush and water to clean it up but its more of a sandy cement that's very hard. Link to comment Share on other sites More sharing options...
Foshunter Posted April 17, 2014 Share Posted April 17, 2014 Very nice display piece----Tom Grow Old Kicking And Screaming !!"Don't Tread On Me" Link to comment Share on other sites More sharing options...
KLM Posted September 23, 2014 Author Share Posted September 23, 2014 Thanks for the information. Sorry for the late post its been a busy summer. Link to comment Share on other sites More sharing options...
Boesse Posted September 24, 2014 Share Posted September 24, 2014 Yup, Auspex and siteseer are right on the money - Dendraster ashleyi from the San Diego Fm. However, the formation is now known to be as old as 4.5 Ma, so the lower marine portion is better categorized as just "Pliocene". Definitely some nice specimens - we get the same species up north in the Purisima Fm., and maybe in the Merced Fm. as well. Link to comment Share on other sites More sharing options...
KLM Posted December 6, 2017 Author Share Posted December 6, 2017 WOW, How time goes by. I would like to get more info on cleaning up this fossil. It was suggested to soak in vinegar to help loosen some of the sandstone. Does anyone think that would help? Thanks again. Link to comment Share on other sites More sharing options...
siteseer Posted December 6, 2017 Share Posted December 6, 2017 2 hours ago, KLM said: WOW, How time goes by. I would like to get more info on cleaning up this fossil. It was suggested to soak in vinegar to help loosen some of the sandstone. Does anyone think that would help? Thanks again. in prep when you're not sure, always go with the most gentle cleaning tools and technique. Check to see the effectiveness of just water and a soft toothbrush. Don't soak the chunk or parts of it may fall apart. If water doesn't do anything, try vinegar. If vinegar doesn't do anything, you can do searches for "cleaning sand dollars" or similar phrases here on the forum. Some encrustations are tough (tougher than the surrounding sand dollar) so you might have to go with a "sand blaster" that shoots powders of various grits depending on how serious you want to get. Some people have used grinders but you might try an old-fashioned metal file - something with a relatively fine filing surface like the one on a Swiss Army Knife. Be patient. Go easy. Look for a local lapidary shop and see if someone has experience with fossils. Check the local gem and mineral clubs. 2 Link to comment Share on other sites More sharing options...
Coco Posted December 6, 2017 Share Posted December 6, 2017 Hi, Most of sea urchins are in calcite. If it is the case, vinegar will "eat" calcite ! Be careful ! Coco ---------------------- OUTIL POUR MESURER VOS FOSSILES : ici Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici Mâchoires sélaciennes récentes : ici Hétérodontiques et sélaciens : ici Oeufs sélaciens récents : ici Otolithes de poissons récents ! ici Un Greg... Link to comment Share on other sites More sharing options...
KLM Posted December 7, 2017 Author Share Posted December 7, 2017 I spent 2 hours working on it today with some vinegar and a toothbrush. Rinsed with cool water afterwards. Made a little progress. Also included a picture of the back side. I would like to expose more layers on the front at the top and bottom and for that matter the back side if possible. Link to comment Share on other sites More sharing options...
KLM Posted December 7, 2017 Author Share Posted December 7, 2017 On 12/5/2017 at 10:42 PM, siteseer said: in prep when you're not sure, always go with the most gentle cleaning tools and technique. Check to see the effectiveness of just water and a soft toothbrush. Don't soak the chunk or parts of it may fall apart. If water doesn't do anything, try vinegar. If vinegar doesn't do anything, you can do searches for "cleaning sand dollars" or similar phrases here on the forum. Some encrustations are tough (tougher than the surrounding sand dollar) so you might have to go with a "sand blaster" that shoots powders of various grits depending on how serious you want to get. Some people have used grinders but you might try an old-fashioned metal file - something with a relatively fine filing surface like the one on a Swiss Army Knife. Be patient. Go easy. Look for a local lapidary shop and see if someone has experience with fossils. Check the local gem and mineral clubs. Thank you! Link to comment Share on other sites More sharing options...
KLM Posted December 12, 2017 Author Share Posted December 12, 2017 I have worked on it several more hours with vinegar and toothbrush but not really getting anywhere. Link to comment Share on other sites More sharing options...
Ludwigia Posted December 13, 2017 Share Posted December 13, 2017 6 hours ago, KLM said: I have worked on it several more hours with vinegar and toothbrush but not really getting anywhere. You could try a wire brush under running water. Bronze is softer than steel, so it's probably better to use the latter. You just have to be careful that it doesn't scratch the fossil. Any residue left by the brush can be washed away with soapy water. It may however become difficult if the hard sediment has penetrated the fossil in places. Then you should leave it as is. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
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