SAN DIEGO ASSOCIATION OF GEOLOGISTS www.sandiegogeologists.org SDAG MEETING ANNOUNCEMENT Wednesday, April 16, 2008 CLEAR WATER SECRETS: A MICROSCOPIC DISCOVERY IN THE CAVE FORMATION STORY presented by Dr. Stephanie Schwabe, University of San Diego Where : Catalina Room (southern end of MVCC) SEE MAP Marina Village Conference Center 1936 Quivira Way, San Diego, CA 92109 When: 5:30 pm – Social Hour 6:30 pm – Dinner 7:30 pm – Program Directions: FROM INTERSTATE 5: Take the SEA WORLD DRIVE exit. From SEA WORLD DRIVE, take WEST MISSION BAY DRIVE on your right. When you see the large green sign that says QUIVIRA ROAD, get in the farthest left of the two left turn lanes. Turn left, go one very short block and turn left again. Drive about one half mile and MARINA VILLAGE will be on your right. FROM INTERSTATE 8:Take the WEST MISSION BAY DRIVE exit to the right. You will be on INGRAHAM STREET for a short distance from which you will take the next exit marked WEST MISSION BAY DRIVE on your right. When you see the large green sign that says QUIVIRA ROAD, get in the farthest left of the two left turn lanes. Turn left, go one very short block and turn left again. Drive about one half mile and MARINA VILLAGE will be on your right. Dinner: Texas Barbecue: Barbecued Baby Back Pork Ribs Charbroiled All-Beef or Veggie Hamburgers Ceasar Salad Corn on the Cob Italian Pasta Salad Dessert Cost: $30; $15 Students; $5 discount for current SDAG Members Reservations: Make your reservation online at www.sandiegogeologists.org no later than noon, Monday , April 14th SDAG - 1 Rev. 0, 1/4/08 2008 SDAG MEETING SCHEDULE – Mark your Calendars! Meetings are usually on the 3 rd Wednesday of the month but may change to accommodate speaker and meeting place schedules. Check here for updates! May 21st Chuck Houser June 11th Joint mtg with South Coast Geological Society, San Juan Capistrano; Jeffrey Keaton July 16th Joint meeting with the San Diego Chapter of AEG; Dorian E. Kuper 2008 EXECUTIVE COMMITTEE PRESIDENT - Sarah Gray; University of San Diego, Ph: (619) 260-4098; fax: (619)260-6874; [email protected] VICE PRESIDENT - Scott Snyder; Ninyo & Moore ; Ph: (858) 576-1000; [email protected] SECRETARY – Bryan Miller-Hicks; [email protected] ; [email protected] TREASURER - Chuck Houser; PetraGeotechnical Inc. ; Ph: (858) 485-5530; [email protected] PUBLICATIONS -Lowell Lindsay; Sunbelt Publications ; Ph: (619)258-4911 x111; fax:(619)258-4916; [email protected] WEBMASTER – Carolyn Glockhoff; Caro-Lion Enterprises, Ph: (858) 549-3396; [email protected] Steffi Schwabe and samples after a dive in a Bahamian Blue Hole SDAG - 2 Rev. 0, 1/4/08 SPEAKER BIO Stephanie Jutta Schwabe, Steffi to her friends, received her B.A. in Geology from the College of Charleston in 1990, her MSc from Mississippi State University in 1992, her Ph.D. in Biogeochemistry from the University of Bristol, UK in 1999, a degree supported by a full scholarship. She also earned a J.D. with focus in International Environmental Law from the University of Queensland, Australia in 2003. She was admitted to the Queensland Bar, both as a Barrister and mediator the same year. A native of Charleston South Carolina, Dr. Schwabe has been diving for over 25 years in the Bahamas, and is the founder and director of the Rob Palmer Blue Holes Foundation, so renamed following her husband’s death in 1997 in a diving accident. She became a celebrity in the dangerous world of cave diving, fought powerful interests to protect the “blue holes” of the Bahamas and as a result her adventurous stories were included in a book titled, “Women of Discovery: A Celebration of Intrepid Women Who Explored the World. She is currently in the editing stages of her own book titled: Living in Darkness: A Women’s exploratory adventures into the Black and Blue Holes of the Bahamas. Her work and adventures have been recorded by Discovery, Discovery Animal Planet, German and French National Television, World of Wonder and by an Australian Production, Beyond Production. ABSTRACT The currently accepted hypothesis for the development of caves in carbonate islands and coastal areas suggest that mixing of CaCO 3 supersaturated sea water with CaCO 3 saturated groundwater creates under-saturated mixed water that is theorized to be responsible for large-scale carbonate dissolution. This hypothesis does not address the dissolutional potential of rainwater migrating through the vadose zone, or the ground water. It is known that soon after rainwater has moved through the soil and made contact with the underlying limestone it becomes buffered by dissolution of CaCO 3. We hypothesize that the dissolution capacity of the vadose water is primarily controlled by the assimilation of CO 2 produced by heterotrophic bacteria living in the pores of the host rock. Rainwater collected before it made contact with the ground on San Salvador Island, Bahamas contained 10 3 bacterial cells per milliliter. In contrast, water collected from dripstones in caves contained >10 4 to 10 5 colony-forming-units (cfu). Wall rocks collected from dry caves on San Salvador Island, Bahamas, contained >10 6 cfu, with the dominant heterotrophic bacteria identified as Actinomycetales , which are known to produce CO 2 and NH 3 as end-products of their metabolism. Discovery of the microbial populations, which comprise at least 16 different species, within the rock samples provides not only a significant potential for the production of CO 2, but for other microbially generated acids. Further, surface and 2.5-cm-deep wall-rock samples sealed in sterile vials for 14 days yielded a CO 2 content that ranged from 770 to 410 ppm above the current atmospheric concentration (~380 ppm). Our observations suggest that bacteria are maintaining and driving the CO 2-related dissolution in the vadose and phreatic zones. It is also likely that secondary porosity and permeability may be enhanced even during periods when the rock is not saturated with water. Limestone in the phreatic zone, especially where they are exposed to the mobile mixing-zone water, experience the greatest removal of solutes, and the greatest concentrations of bacteria. As a result, it is reasonable to suppose that void enlargement reaches the highest rates in association with those environments. Hence, caves develop and enlarge to their greatest extent at or near sea level. This can also explain why caves, which experienced only relatively short episodes of phreatic conditions can be so large. SDAG - 3 Rev. 0, 1/4/08 ANNOUNCEMENTS Presidents Corner, April 2008 Happy Spring. This month we welcome you to join us for a Texas BBQ at Marina Village with Dr. Stephanie Schwabe from USD, who will speak about her exciting new ideas about the role of microbes in cave formation in Bahamian blue and black holes. If you wondered what it was like to dive into a black hole, come see some of her awesome underwater video footage. On Sunday April 13 th , John Warme of the Colorado School of Mines will be leading a field trip along the sea-cliffs at Torrey Pines. If you are interested, contact Jared Marrow at SDSU ([email protected] or [email protected]). Watch for details of May’s meeting at the Model Train Museum in Balboa Park, with a presentation by our own Chuck Houser. Sarah ONE STOP WONDER, The Amazing Geologic History of the Eocene Ballena Gravels Saturday, April 26 th , Pat Abbott, Prof. Emeritus, San Diego State University will be leading the One Stop Wonder. Trip participants will meet at 9AM in the parking lot of the Sizzler Restaurant on the south side of Hwy 78 on the east side of town in Ramona. From there we will caravan to Whale Mountain between Santa Ysabel and Ramona to a private ranch located opposite the large egg ranch near Santa Teresa Valley. The trip will conclude before noon, with an option of joining the group for lunch. Thanks to Mike Hart and Dave Bloom for organizing the logistics. Trip participants will meet at 9AM in the parking lot of the Sizzler Restaurant on the south side of Hwy 78 on the east side of town in Ramona. From there we will caravan to Whale Mountain between Santa Ysabel and Ramona to a private ranch located opposite the large egg ranch near Santa Teresa Valley. The trip will conclude before noon and those that would like can get together for lunch at the sizzler in Ramona or head on into Santa Ysabel for lunch there. The provenance of the Poway Conglomerate is one of the most interesting geologic stories in California. The Poway Conglomerate was delivered to the San Diego coastal plain by a large river whose remains are the Ballena Gravels. As in the Sierra Nevada, the Eocene rivers carried gold. Near Whale Mountain the gold was mined in the late 1800s and early 1900s; the gold placers produced only small amounts of gold compared to the mines of Julian to the east, partly because of the lack of water. The distinctive red rhyolitic clasts of the Poway Conglomerate began their journey to the Pacific Coast in latest Paleocene via a large river system that originated in Laramide-rejuvenated Jurassic volcanic mountains that now lie in Sonora, Mexico. Opening of the Gulf of California carried the Eocene gravels away from their source rocks in Sonora, Mexico. Remnants of the river channel in the east county are now visible as the Ballena Gravels that occupy the crests of several ridges and peaks south and east of Ramona and represent classic inversion of relief where a onetime valley floor now occupies a sinuous ridge.