Geoscience Reports --- No. 20, Spring 1996

GEOSCIENCE REPORTS — Number 20, Spring 1996

p.1 • Radioisotope Age, Part I • R. H. Brown
p.4 • Editor's Angle
p.4 • Scattered Notes from the Scientific Literature - Chemistry, Geology, Microbiology, Paleontology
p.6 • Geoscience Research Institute News

EDITOR'S ANGLE

    From a creationist's perspective, the geochronologists' application of radioisotope dates to the geologic column and their use of these dates as evidence for ancient life is a difficult topic to tackle. Dr. Brown's explanation of inherited age helps us understand some of the conflicts in radiometric dating of igneous deposits.
    Some creationists argue that radiometric dating produces inconsistent dates. It is true that the scientific literature provides numerous examples of disputes among workers over the ages assigned to various bodies of rock. However, arguments addressing the margin of error within a few million years in a time-frame of hundreds of millions of years are not very helpful in establishing the recent appearance of life.
    It needs to be made clear here, that this is not the kind of issue that Dr. Brown is dealing with in his article. Conflicts in the dates that are orders of magnitude apart, like those cited in Dr. Brown's article, are helpful to us as we study and assess the dates and the processes related to the determination of those dates.

SCATTERED NOTES FROM THE SCIENTIFIC LITERATURE

CHEMISTRY

Khalil MAK. 1995. Decline in atmospheric carbon monoxide raises questions about its cause. EOS, Transactions, American Geophysical Union 76(36):353-354.

Scientists have been tracking concentrations of carbon monoxide (CO) in the atmosphere globally for the past 15 years. These concentrations vary regionally over the earth. Spectroscopic data show a rapid decline in CO since the later half of the 1980s. Increases in CO causes a decrease in hydroxyl radicals (OH). Since OH removes both man-made and natural pollutants from the atmosphere, it is in the best interests of humanity to minimize CO production. The reduced levels in the northern hemisphere were attributed to regulation of automobile emissions. Reduction of CO in the southern hemisphere may be due to less biomass burning in the tropics.

GEOLOGY

White MC. 1995. Finding documents split of Indo-Australian plate. EOS, Transactions, American Geophysical Union 76(34): 337,343.

James Van Orman and his colleagues have reinterpreted a large region of deformed ocean crust in the central Indian Ocean as a distinct boundary zone between well-defined Indian and Australian plates based on seismic reflection profiles through the area.
Previously, the zone of deformation had been interpreted as intra-plate buckling and had posed a problem for the plate tectonics theory. (According to the theory, plates can only deform at their boundaries.) The splitting of the Indo-Australian plate increases the number of major lithospheric plates to 13 and resolves the intra-plate conflict. One researcher suspects the boundary will eventually become a subduction zone. The boundary is unusual because it extends for 900 kin from north to south. (Most boundaries are only 10 to 15 km wide.)

Verplanck PL, Farmer GL, McCurry M, Mertzman S, Snee LW. 1995. Isotopic evidence on the origin of compositional layering in an epizonal magma body. Earth an Planetary Science Letters 136:31-41.

Bodies of molten rock within Earth's crust are called magma chambers. It is common for the chemical ions in the magma chambers to fractionate and create zones of mineral combinations that make up a variety of rock types: granite, diorite, syenite, etc. A wide variety of processes is responsible for the zonation including 1) melting of the magma chamber roof or wall rock, 2) upward migration and ponding of differentiated magma, and 3) sequential input from another magma body. Recent research of the Organ Needle pluton (a magma body that is now exposed hard rock) in New Mexico suggests that a more buoyant magma formed by the interaction of the main magma body with the granitic wall rock. The more buoyant magma then moved marginally along the outside boundaries of the chamber and collected at the top of the magma body forming a cap on the pluton. Several problems were noted in the study of these processes. 1) Imperfect sampling, e.g., volcanic ashes may not reflect the true mineralogy of the main body of the pluton. 2) Late-stage zonation occurs in the cooling process. Since the ratios of the radioisotopes constitute the database for radiometric dating, these processes and problems may have important implications for the ages assigned to the plutons and other volcanic deposits.

MICROBIOLOGY

Svitil KA. 1995. Dinosaur Mine: Discover (May):36-37.

Svitil reviews the work that has been done to recover dinosaur DNA. The most promising work comes from a microbiologist, Scott Woodward at Brigham Young University in Utah. Bone fragments were recovered from a sandstone overlying a coal bed. The fragments were original bone material; not mineralized. Standard techniques were used to recover and identify a segment of 174 base pairs from the cytochrome b gene. The sequence is not particularly similar to DNA from living organisms but it is more similar to whale DNA it is to birds or reptiles. Unfortunately, the bone fragments may not have been positively identified as dinosaur bone material and the possibility of plant and/or fungal contamination is very high, especially with the associated coal bed. Dinosaur DNA has not yet been positively identified.

PALEONTOLOGY

Ahlberg PE. 1995. Elginerpeton pancheni and the earliest tetrapod clade. Nature 373:420-425.

A new genus of tetrapod has been described from the lower portion of the Upper Devonian deposits of Scotland. Organisms classified as tetrapods typically have limbs; however, E. pancheni has been identified on the basis of skull and jaw structures. (It has not yet been determined whether the animal had limbs or fins.) The jaw of E. pancheni is much longer (400 mm) and narrower than other Upper Devonian fish and amphibians. The jaw is almost twice as long as the amphibian, Ichthyostega. Since the genus is structurally diverse, it was assigned to a sister group of Tetrapoda. In many ways the new genus has added to the confusion over which features best describe the ancestral relationships for the evolutionary theory of fish to amphibian. The new genus suggests there were two main groups of tetrapods: 1) the "ancestral" line in which each genus is from a single locality (these genera have a uniform skull and jaw shape); and 2) the "sister" group with unique skull and jaw shape found from Scotland to Russia. Despite the abundance of intermediate forms, no "ancestral" transitions from fish to amphibian have been positively identified.

Wu X, Sues H, Sun A. 1995. A plant-eating crocodyliform reptile from the Cretaceous of China. Nature 376:678-680.

Crocodile teeth are typically very uniform; however, a crocodile with unique dentition has been identified from China. Its tooth structure is similar to that of molars with cusps that have sharp, concave cutting edges. Molar-like teeth are common in herbivores with a fibrous diet. Skeletal structures and some jaw features are very similar to those of the Gondwana crocodiles. These similarities suggest increased biogeographic diversity of the crocodiles in the lower Cretaceous sediments.

GEOSCIENCE RESEARCH INSTITUTE NEWS

Current Research

Dr. Clyde Webster studied an Eocene "fossil forest" locality in Bridgewater Bay, Australia, during September 4-17 (Fig. 2). Although there is no petrified wood at this locality, there are some unusual cast structures. These structures are filled with a non-stratified red, sandy clay and in some places are vertically stacked in two to three stratified layers. The distribution density of the cast structures is many times greater than the density of a standing forest. An alternative interpretation suggests that the structures are solution pipes; however, the physical data do not support this hypothesis. The size, shape and distribution are not what one would expect for solution pipes.

Figure 2. Unusual sedimentary sructures at Bridgewater Bay, Australia. Photo courtesy of Clyde L Webster.

Dr. Ben Clausen has been working diligently to "get his numbers crunched" before the La Sierra University VAX is shut down. Just as electrons orbit the nucleus in shells; protons and neutrons exist within shells in the nucleus. Dr. Clausen's research is concerned with the transitions of particles from one nuclear shell to another. He conducted an experiment to test current theories about the nuclear shell model. He has found the electron scattering theory to be reasonably good but the pion scattering theory needs more work. [A pion is a particle that has a mass intermediate between an electron and a proton. It has a short halflife that is measured in nanoseconds. Pions help hold the protons and neutrons together in the nucleus.]

Research Presentations

Drs. Arthur Chadwick and Elaine Kennedy presented their research at the Third Biennial Conference on Colorado Plateau Research in Flagstaff, Arizona, October 16-19. Their abstract was entitled, "Depositional Environment of the Tapeats Sandstone in the region of the Grand Canyon, Arizona." Previous workers had identified the Cambrian Tapeats Sandstone as a slowly deposited, shallow marine sand (Fig. 3). Dr. Chadwick presented evidence that the Tapeats Sandstone was rapidly deposited in a deep marine environment. Chadwick and Kennedy concluded that "the submarine flows of Tapeats Sandstone were deposited on a surface with over 140 m of vertical relief and would have required depths in excess of 200 m" below storm wave base. A formal paper has been submitted to the Proceedings of that meeting.

Figure 3. Drs Chadwick and Kennedy standing on Tapeats Sandstone in the Grand Canyon, Arizona. Photo courtesy of Ann Brennan.

Dr. Elaine Kennedy attended the annual Geological Society of America meetings in New Orleans, Louisiana, November 6-9, to present research she conducted with Dr. Lee Spencer in collaboration with Prof. Carlos Steger, Director of the South American Geoscience Research Institute Branch Office, based at River Plate Adventist University, Argentina (Fig. 4). The title of their published abstract was: "An Unusual Occurrence of Dinosaur Eggshell Fragments in a Storm Surge Deposit, Lamargue Group, Patagonia, Argentina." The authors concluded that the "presence of eggs and eggshell fragments may not indicate the presence of in situ nesting areas." Research continues on the shell material. At present at least eleven different kinds of shell material have been identified.

Figure 4. Professor Carlos Steger standing on sandstone outcrop containing dinosaur eggs. Photo courtesy of Elaine Kennedy.

Teaching Responsibilities

Dr. Jim Gibson taught a graduate course on biogeography for Loma Linda University's Natural Sciences Department. The class studied the distributions of vertebrates and flowering plants. They included information on the effects of climate on the distribution of the organisms and looked at the biogeographical distributions of the fossil record.
Dr. Clyde Webster also taught a graduate course on aqueous geochemistry for the Natural Sciences Department. The focus on aqueous geochemistry is intended to help students understand the complex geochemistry of marine and freshwater systems.

BRISCO Report

The Biblical Research Institute Science Council (BRISCO) held its annual meeting in Grand Junction, Colorado from August 11-15, 1995. Forty scientists and theologians met to discuss science and religion issues. The meetings emphasized two areas of study: issues in molecular biology and the Mesozoic portion of the geologic column. Abstracts of the thirty presentations and copies of the field guide are available from the Geoscience Research Institute.

Figure 5. Cretaceous Mesaverde Sandstones, one of the stops during the BRISCO field trip.
The Mesaverde Group forms the spectacular Book Cliffs north of I-70. These freshwater sandstone deposits contain coal beds (arrow A) that are interpreted as swamp deposits. In addition, a Hadrosaur (duck-billed dinosaur) skin impression was found in the sandstone near here, and it is well-known that some of the coals have dinosaur tracks associated with them. Despite the overall sense that these are flat-lying sand bodies, closer inspection reveals considerable soft-sediment deformation and sedimentary structures (cross-bedding, current ripples, scour features (within the sandstone beds (arrow B). The strata have been interpreted as freshwater stream deposits that merge to the East with coastal plain deposits.
Above the Book Cliffs is the Tuscher Formation representing the top of the Cretaceous deposits. At the top of the Tuscher is an erosional unconformity that has been attributed to the Cretaceous-Tertiary (K-T) boundary impact/extinction event. The complexity of the deposits we have examined compel us to reject simplistic flood models and point us toward the need for a multidisciplinary approach to flood modeling.

Spring No. 20

Editor - M. Elaine Kennedy
Associate Editor - Katherine Ching

Subscription requests, correspondence, and notices of change of address should be sent to: Publications Editor, Geoscience Research Institute, Loma Linda University, Loma Linda, CA 92350 USA. Annual subscription rate is $3.00 (U.S. currency).

Geoscience Reports is a newsletter published by the Geoscience Research Institute to present current happenings at the Institute as well as general-interest articles that deal with creation/evolution issues for elementary/secondary-school and college science classes. The views expressed are those of the authors and not necessarily those of the Institute.

Staff of the Institute: L Jim Gibson, Director (PhD, biology); Ben L Clausen (PhD, nuclear physics); M Elaine Kennedy (PhD, geology); Ariel A Roth (PhD, zoology); Clyde L Webster PhD, chemistry); Katherine Ching. Editor (MA, history); and Janet Williams, Administrative Secretary.

| Previous Page | Home Page |