Lone Pine Gem & Mineral Society Newsletter
April 2008
Messages From Our President
The following sections come from notes from Fancis.
The Gem and Mineral Show
There is only one meeting remaining before our show. We will have sign up sheets for members that will help and we need lots of that. We need displayers. Do you have a specimen or rock collection you would like to display? Or any thing else? We have display cases; maybe you could combine with someone else. Let me know. Reach me at franceem AT qnet.com or call me at 760-876-4319.
New Meeting Location Search Goes On
Some of our members are pursuing possible meeting locations for the club meeting. Reports to be given at the April meeting.
March Field Trip
Although Ray's report on our last field trip to the Nova garnet location appears later in the newsletter, I just want to thank the 11 really dedicated rockhounds for persevering in the face of some really nasty weather. Francee and I left after showing the hounds where the site was and what to look for.
Report on Pending Road Closures
Francee and I have been attending meetings in Bishop about the pending redesignation and closures of hundreds of roads in the Inyo National Forest. We are part of a group made up of members of the Sierra Club, Friends of the Inyo, Audubon Society, California Off Road Vehicle Association, Inyo County Board of Supervisors, Lone Pine Gem and Mineral Society, California Federation of Mineral Societies, Gear Grinders, other OHV groups and individuals. The purpose of these meetings is to present to the Forest Service a consensus recommendation about specific roads/trails that are targeted for action by the Forest Service. We only have the month of March to accomplish this task because of time constraints that the Forest Service is working under. Given that, we are only able to review a small percentage of the inventoried roads/trails. Each member of this group is proposing only the roads/trails that are most familiar and important to them. This process is working because we agreed in the beginning to work towards compromise solutions on all the roads/trails that we have reviewed. Hopefully what we are doing will have a positive impact on this entire project. The public will have a chance to voice their opinions when the draft plan is released later this year.
Dick Freisen Gem Stone Carving Class
We have two people signed up for the class that will be held in August. We need at least two more but no more than 4 more. Max 6 students. Cost is $100 per student. The class includes 7 hours of instruction, all carving equipment and one stone (usually obsidian). We will hold this class in our house with swamp cooling.
We need two more sign ups to confirm a date. Dick comes from Livermoor, CA. His classes are in high demand.
Field Trips
This report comes to us from Ray Ramirez.
March Field Trip to Nova Garnets
Our March 16th field trip to Nova garnets had eleven participants, six of which braved the elements to reach the garnet location high up the hill. Unfortunately it was quite windy and cold and without many layers it made it a bit uncomfortable to be out for too long. The other five members searched the lower flats near the cars. The lower areas had quartz crystals and fragments as well as some garnets that made their way down the mountain and the higher areas had lots of garnets and epidote. We searched for the moss agate area with no luck and found no evidence of scheelite. The Joshua trees and wildflowers were in bloom. Those of us who were bundled up and who climbed up to the ridge found lots of garnets and epidote. All in all, it was a great day and I think everyone enjoyed the trip.
April Field Trip to Saline Valley
Next month we will hopefully visit the Saline Valley quartz crystal area. I had the opportunity to check road access from the North and found it passable with high ground clearance and four-wheel drive. I would like to shoot for Sunday April 13th and meet at the Big Pine Triangle campground at the junction of Hwy 395 and Hwy 168 at 8:00 AM. Plan to bring a lunch with you to the collecting area. As far as tools, bring a rock hammer, crack hammer, hand rake and anything one would generally bring to collect quartz. Don't forget gloves for sharp edges and a good supply of water. Also the lower location has small jewelry points and a small screen may work well. The upper area is on much steeper terrain and only you mountain goats who feel safe on steeper slopes may want to venture higher for larger crystals. From the campground the trip will cover 32 miles. Of those 32, 12.7 are on pavement and the next 18 are on decent dirt road. The last 8 tenths of a mile are rough rocky road with room for perhaps 8 or so vehicles as far as parking near the location. Looking forward to seeing you all for the Saline trip!
Until then Happy Hounding! - Ray Ramirez
Precambrian - Cambrian Boundary in Inyo County
543 Million Years Ago (MA)
This article comes to us from Roger De Hart who offers to share his knowledge of geology with us. Thanks, Roger. - Linda
The PreCambrian–Cambrian boundary (PC-C) is one of the most important intervals in the history of life on earth. It marks the appearance and diversification of multi-celled animals, the invasion of the burrowing and tunneling sea bed animals, the start of biomineralization (shells/trilobites), predation of animals, and the start of major plate tectonic and atmospheric changes.
The Cambrian Period contained an interval called the “Cambrian Explosion” which lasted for only 10 million years (or less) in which all except two of the current living animal phyla appeared. The two not occurring during this “explosion” were Poriferas (sponges) which was already present and the Bryozoa (moss animal) which have not yet been found in the Cambrian Period.
The Global Standard Stratotype Section and Point (GSSP) for the PC-C boundary was determined to be at Fortune Head, Newfoundland by the International Union of Geological Sciences (IUGS) in 1992.
The IUGS also selected the world-wide trace fossil (Trichophycus pedum) to coincide with the PC-C boundary.
Trichophycus pedum: One of the earliest animals (worm?) found in great abundance. It produced a fairly complicated and distinctive burrow pattern. It made successive probes vertically through the sediment in search of food, generating a trace pattern reminiscent of a fan or twisted rope. Previously, animals (worms) burrowed horizontally and parallel with the bedding plane of the sea sediments.
This fossil (T. pedum) is restricted to siliciclastic types rocks (i.e. sandstone) like at Fortune Head, Newfoundland. In fact, 70% of the rocks at the PC-C boundary world-wide are siliciclastic rocks.
Thus, it was difficult to correlate this world-wide fossil (T. pedum) with many of the Precambrian-Cambrian boundary sections in the world that contain only carbonate rocks. Many fossils found in these carbonate rocks are local and not globally distributed and therefore cannot be used as guide (index) fossils.
The southern Great Basin contains thick, relatively complete, well-exposed and easily accessible rock formations that contain siliciclastic rocks and the boundary-marking fossil (T. pedum) in association with carbonate rocks that also contains a complete chemostratigraphic profile.
The Inyo-White Mountains contains this mixture of siliciclastic-carbonate rocks and has allowed researchers to analyze the rock formations, the fossils they contain, and the chemistry of the rocks in relationship with each other.
Until recently, geologists had assumed that the presence of the earliest occurrence of small shelly fossils (SSFs) marked the PC-C boundary. Therefore, the Reed Dolomite in the Inyo Mts. which contains a shelly fossil (Cloudina) was identified locally as the start of the Cambrian Period. The Devil’s Gate on the Big Pine-Death Valley Road just east of Big Pine is composed of Reed Dolomite.
The Deep Spring Formation overlies the Reed Dolomite. The fossil, T. pedum, has been found at the middle member of the Deep Spring Formation in the Mt. Dunfee area just east of Gold Point, NV and also in the White Mountains. Therefore, the Deep Spring Formation is now considered the start of the Cambrian Period in this area and not the Reed Dolomite.
T. pedum has also been found in the lower Wood Canyon Formation in Boundary Canyon located in Death Valley National Park as well as at Chicago Pass in the Nopah Range. The Wood Canyon Formation is thus the same age as the Deep Spring Formation (deposited at the same time).
Besides the fossil (T. pedum), chemostratigraphy provides another technique for determining the PC-C boundary.
There is a major world-wide positive carbon isotope excursion (digression) dated at 548 Ma and coincides with simple horizontal trace fossils and Cloudina (Reed Dolomite). This is followed by a pronounced world-wide negative carbon isotope excursion nearly coincident with the PC-C boundary (543-542 Ma) which coincides with the first presence of T. pedum. This is followed by a return to a positive carbon isotope excursion.
The lower member of Deep Spring Formation shows this positive carbon isotope excursion. The middle member shows the negative carbon isotope excursion along with the appearance of T. pedum. The upper member then returns to a positive carbon isotope excursion.
This negative carbon isotope excursion is also found the in the lower member of the Wood Canyon Formation in Death Valley National Park and Chicago Pass in the Nopah Range where T. pedum has been found.
Therefore, the start of the Cambrian Period is established (for now) at 543 Ma. based on both fossil and chemostratigraphy evidence. The PC-C boundary in INYO COUNTY is located in the Deep Spring and the Wood Canyon Formations.
Trichophycus pedum (Treptichnus pedum) was one of the earliest animals and found in great abundance. It produced a fairly complicated and distinctive burrow pattern along with a central, sometimes sinuous or looping burrow. It made successive probes upwards through the sediment in search of nutrients, generating a trace pattern reminiscent of a fan or twisted rope.
It is considered more complex than earlier Discern fauna. Its trace fossils, which occur worldwide, are usually found in strata above them. It is used to demarcate the boundary between the Precambrian and Cambrian divisions of the geologic time scale. The reference section is at Fortune Head, Newfoundland.
Since it lacked any hard anatomical features, such as shells or bones, no fossilized remains have been found. This example comes the Nama Group in Namibia, Africa.
Sources
PC-C Transition in Death Valley, United States by Corsetti and Hagadorn, 2000
PC-C Transition in the S. Great Basin by Corsetti and Hagadorn, 2003
Upcoming events
- Club meeting night: April 7, Monday, at Lo-Inyo Elementary School at 6:30 pm. Join us for dinner at the Bonanza at 5:15.
- Shop night: April 8, Tuesday starting at 7:00 pm. Join us at MacDonald's at 6:00 for dinner.
- April field trip: April 13, Sunday at 8:00 am. Meet at the junction of highways 395 and 168.
- Lone Pine Gem & Mineral Show: May 2, 3, and 4.
Contact numbers
- President: Francis Pedneau - 760-876-4319; franceem AT qnet.com
- Vice President: Ray Ramirez - 760-872-0624
- Show Chairman: Jeff Lines - 760-872-6597
- Newsletter editor: Linda Jeffries - 760-876-1009; linda AT lpgms.org
