Fossils — Things of the past

(Conclusion) Uses of fossils

So, why do we have to dig old bones and traces of animals and plants? Is it just one weird hobby? Very well, yes, fossils have a very crucial role in the environment and in our economy. Don’t you know that the diesel, gasoline and LPG that we use every day as well as coal used to power some factories like cement factories come from fossils? The organisms that form into these fuels die a natural death and are buried deeply by tons of sediments that have accumulated for millions of years. Whereas the diesel, gasoline and LPG come mostly from single-celled microorganisms that once lived in the oceans and lakes and other bodies of water, coal comes from woody plant materials. By the perfect combination of long periods of time, plus the extremely high temperatures and pressures in the earth, these organisms are "cooked" to produce crude oil which are later stored within the spaces of rocks. The Philippines and the world as a whole get 60 percent of its energy from petroleum and natural gas. We have the Malampaya deep water gas-to-power project, the biggest natural gas project in the world today. The project produces about 3.4 trillion cubic feet of natural gas which can supply 2,700 megawatts of power to Luzon for 20 years. Since January 2002, it has been providing 30 percent of the country’s energy requirements.

Coal, on the other hand, is the second largest source of energy, contributing about 23 percent of the world’s total energy demand in 1995. When woody plants decompose in ancient swamps and deltas and get accumulated for millions of years, they form layers upon layers of sediment and decaying plant materials. These materials experience elevated pressures and temperatures which would cause the changes within these beds to form coal deposits. Approximately, an accumulation of decaying plants as high as a tall building like the Shangri-la Plaza can produce just a meter thick of coal deposit. One coal mine here in the Philippines can be found on Semirara Island off Mindoro island-province.

Fossils of plants and animals are also essential tools in identifying old environments and interpreting paleoclimates. How, you may ask. By looking at the manner their living representatives or relatives behave and react to conditions of today, we are able to understand the environment under which they existed. This is an idea introduced to us by the Father of Modern Geology, James Hutton. According to him, "The present is the key to the past." Following this thinking, we would know that fishes are aquatic organisms, so that if we see bones of fishes embedded in a rock, that particular rock must have formed underwater. If that rock is already at the mountaintop now, some processes, like lowering of the sea level or continental uplift, could have happened for it to be exposed in its present location. Another important issue is about the climate. Are we approaching another ice age or another period of global warming? By studying fossils like foraminifera, we can produce a "saw-tooth" graph that can give us patterns of the climate for millions or thousands of years and help us predict future climate changes. Migration patterns of plants and animals living in the past can also tell us where the polar ice extended to at that particular time. Fossils can also give us clues on how plants and animals reacted under extreme cold or warm episodes in order to survive. Also, the appearance and extinction patterns of different species, like the reptiles, can also help us study lineage and better understand what caused some living forms to be erased from the fossil record. Were there catastrophic events like volcanic eruptions, asteroid impacts, tsunamis or landslides which caused their extinction?

Did you know that these fossils are "buried clocks" which can assist geologists give an age and establish the order of deposition of layers of rocks? Yes, fossils, indeed, can tell us the time when the rocks that bear them were formed. In oil companies, for instance, core samples (sediments containing fossils) are analyzed to know if they have already reached the particular rock containing petroleum. Certain fossils called index fossils characterize a certain age range. Fossils can also help correlate rocks with the same age but from separate locations.

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Marietta M. de Leon obtained her Ph.D. in Geology from the University of the Philippines. She is currently an associate professor at the National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman. Her fields of specialization include Micropaleontology (Foraminifera and Calcareous Nannofossils) and Biostratigraphy, mainly with application to petroleum exploration. Send queries or comments on this article to [email protected] or [email protected].

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References:

De Leon, M.M. and Ocampo, J.A.A. Philippine Paleontology in the Second Half of the 20th century and its direction in the 21st century. (In preparation)

Shrock, R.R. and Twenhold, W.H. 1953. Principles of Invertebrate Paleontology. McGraw-Hill Book Company, Inc. The Maple Press Company, York, PA. 2nd Ed.

Turbucks, E.J. and Lutgens, F.K. 1984. The Earth: An Introduction To Physical Geology. Charles Merrill Publishing Company. A Bell and Howell Company, Columbus, Ohio. 1st Ed. p146-148.

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