The Earliest Paleontologists

The ancient Greeks recognized that marine shells found in outcroppings around the Mediterranean Sea marked areas that had once been under water. Herodotus, the Greek historian and traveler, mentioned fossil sea-shells he had seen in Egypt and drew the conclusion that the sea had at some time covered Lower Egypt. But other Greek thinkers left behind some mischievous ideas, such as Aristotle's teachings that there had been only a single creation. These ideas became mingled with the Church's dogma...

Other Natural Exposures

There are natural exposures of rock in mountain cliffs and hillsides, especially in the West, that have never been explored by a fossil hunter. Some, such as sedimentary rock caps in the Rocky Mountains at 1 0,000 and 12,000 feet, are nearly inaccessible. Topographic maps give clues to such potential fossil sites look for steep hillsides and cliffs, which are evident on the maps. Shark teeth found at Calvert Cliffs. Similar fossils are found in Florida on beaches and in phosphate pits. (Photo...

Code of Ethics

An Emily Post for paleontologists might include the following 1. Get permission to enter and to collect on private or public property. Most public property is open, but it may be closed because it is under a mining claim or has been withdrawn from unrestricted use for some other purpose. Finding the owner of private property may require some investigation, because property changes hands frequently in this restless age. 2. Do not drive through or otherwise damage growing crops. In farming...

Use Them

A map, for the purpose of an amateur collector, is a generalized representation on a flat surface of some aspect of the surface of the earth. It may be a road map, such as those that filling stations give away a topographic map, which expresses a third dimension through such a device as contour lines or a geologic map or other more specialized type that shows the nature of the surface rocks, or economic and geographical features. In this automobile age, the collector will, of course, find road...

Getting Lost

Getting lost is perhaps the greatest hazard the collector faces. The desert is a place of austere beauty and of harsh extremes. The mountains turn a forbidding face to the person unfamiliar with them, but it is possible to live, and live well, in both environments. If you get lost, don't panic. Stay with your companions, take shelter where you are, and try to enjoy the situation as you wait for rescue. Prospectors in such situations have been known to live on fern shoots, pinon nuts, and the...

Other Areas

Any exposure, natural or artificial, is worth looking into. Any area known to have produced fossils, even in the most built-up areas, may at some time have a construction project that will again expose fossil-bearing rocks. Some likely places are described here. House and office-building excavations During construction of building foundations in downtown Kansas City a number of years ago, a layer of shale was dug out that was loaded with superb crinoid crowns. It is difficult to collect in...

Rivers and Creeks

A river or creek draining an area that has exposures of fossiliferous rocks is bound to have a few durable fossils mixed with the gravel in its bed. While rivers and streams do not produce quantities of good fossils, they may provide clues to productive areas in the rocks. Any detailed map, particularly any topographic map, clearly shows all rivers. Rivers in any part of the United States known to have sedimentary rocks of Paleozoic or younger age are potential fossil sites. (See state maps in...

Emergency Water

In an emergency, it is possible to make the desert yield enough water to sustain life for a while. All that is needed is a six-foot-square sheet of polyethylene or Mylar plastic, the stuff of which painters' drop cloths are made. A hole about three feet across and twenty to twenty-four inches deep is dug in the sand. A pail or quart can is placed in the bottom of the hole. Over it the plastic sheet is draped, and a small stone is placed with its lowest point over the collecting cup. Stones...

Formations

But in practice and in principle, it is common and necessary to identify rocks as a formation, the name of which is usually a compound of a typical location and the rock type, such as the St. Peter sandstone or the Trenton limestone. If the formation consists of more than one type of rock, for instance, if it is of shale and limestone, it may be called by a more general name, such as the Supai formation, which appears in the walls of the Grand Canyon, or the Morrison formation, famous for its...

Removing Matrix

After preliminary cleaning of the fossil, bits of matrix may still mask important details. Removal of these pieces to aid identification and create a more attractive display specimen requires skill and infinite patience. It takes at least an hour to clean a small trilobite which has soft, relatively easy-to-remove shale embedded between its ribs. It may take days to clean a limestone slab with many crinoid crowns. The principle behind cleaning matrix from a fossil is to exploit the difference...

Convergence

Fossils were at one time classified primarily by similarities of structure of the hard parts of organisms. This was found to be misleading as paleontologists discovered that some entirely unrelated creatures had developed similar structures, presumably because they were useful to different organisms that had adopted similar ways of life. This trick of nature, which Professor George Gaylord Simpson has called the bane of the taxonomist, is called convergence. Perhaps the most obvious example is...

Cataloging And Displaying Fossils

Fossil Infrared Photography

A jumble of fossils on a shelf is nothing but a heap of curiosities of neither scientific nor monetary value. Among them may lie a one-of-a-kind fossil, a new species, perhaps even a missing link that could throw light on the relationships of some group of plants or animals. Or a common fossil may take on new interest because it is from a locality where such a species has not been found before or from a rock series in which it has never been seen previously. But if the fossil has not been...

Special Techniques

Cast And Mold Fossils

Every collector needs to know something about techniques that are more complex than the methods of preparation we have described so far. These are now-and-then matters the preparation of certain unusual fossils that require specialized treatment. As the collector becomes more skilled in his work with fossils he will wish to go beyond the scraping, chipping, and other methods that had formerly sufficed. Such techniques as the making of peels, thin-section work, and plastic embedment are not...

Sedimentary Rocks

Sedimentary rocks, however, are the principal bank on which the fossil collector will draw. Knowledge of the principal types, the conditions under which they were formed, the relationships of the strata he will work in Fossils in slate are often distorted. This trilobite, Ogygopsis klotzi, comes from Cambrian slates exposed on Mt. Stephen in British Columbia. It is flattened but shows little distortion otherwise. Fossils in slate are often distorted. This trilobite, Ogygopsis klotzi, comes from...

Poisonous Plants and Insects

Woodcraft will enable the collector to identify and shun poison ivy and poison oak. Anyone who is sensitive to their irritants should learn in self-defense to recognize these plants. Washing with soap as soon as possible after exposure is the recommended remedy. Sunburn and windburn are among the minor perils of the outdoors. Much discomfort can be avoided if the body is covered. Should one be burned, however, baking-soda solution will ease the discomfort, and the moist soda will also relieve...

Dolomite

Poorly Preserved Fossils

Dolomite is a half brother of limestone. It is a calcium magnesium carbonate in which part of the calcium of limestone has been replaced by magnesium. This replacement is believed to have taken place while the carbonate precipitate on the sea bottom was still soft. Much recrystalliza- Poorly preserved snail typical of fossils found in dolomite. This specimen is both mold and cast the mold of the outer shell is apparent as radiating lines the cast of the inside of the first whorls protrudes in...

Where Fossils Occur

Strange Fossils Found

Sedimentary rocks, particularly shales and limestones, are the storehouse of 99 percent of the world's fossils. One of the three major types of rocks that form the crust of the earth, these rocks are distinguished from the other two types because they are formed of sediments. Some are composed of silt, sand, and pebbles deposited mechanically by wind and water some are chemical sediments precipitated from water or taken from water by plants and animals and then deposited with their bodies and...

Classifying Plants And Animals

In what is known as the Linnaean system, each organism animal or plant, living or fossil is identified by two names. The first is the generic or general name the name of the genus , which is written with a capital letter the second is the trivial name, which is not capitalized. Latin and Greek words are adapted to the purpose of naming organisms so that the names will be identical in all countries and all languages. Thus man is Homo sapiens the common cat is Felis domestica and the common...

Major Surgery

There is a temptation to trim off as much matrix as possible in the field to save weight. Especially with limestone slabs, this can result in breaking the fossil in half where the fossil creates a weak spot in the slab. It is safer to take the heavy slab home and trim and saw it to size there. If the block enclosing the fossil is too large to transport, a channel should be cut around the fossils with a small cold chisel and hammer. The chisel should be held so that it points away from the...

Foreword

Some years ago, I clipped a sentence from an abstract in the program of the annual meeting of the Geological Society of America, and pasted it to the bookshelf by my desk. I no longer remember who was the author of this quotation, and I don't know whether his tongue was in his cheek when he wrote Geologists are the most literate of all technical writers. Skilled in a descriptive science, strong on grammar, they are beautifully, even romantically fluent. Perhaps there is an affinity between the...

Absolute Time

Opportunities to come as close to a geological event as that at Mecca are few. Certainly it is generally far beyond the scope of the system of relative dating described above, which is one of the two measures that geologists have when they speak of time. The other measure they use is a clock that records absolute time by measurement of changes in radioactive elements in the rocks. Such elements decay at a constant rate, the works of an atomic clock that ticks steadily but so slowly that its...

The Holotype

Helicoplacus

Classification is based on recognition of similarities. The species, the category of classification immediately below the genus, comprises organ isms that are similar to one another and are capable of interbreeding and producing fertile offspring. In order that other paleontologists will have a concrete example for recognition of the characteristics of the species, the person who first describes and names it designates a specimen as the holotype, or sometimes he designates a group of like...

Borings

Images Borings Fossils

Bored holes are quite common, particularly in shells, both modern and fossil. Some are the work of predatory snails that rasp a tapering hole through the shell to get at the delicate meal inside. Borings are made in These California snails show neat holes bored by a cannibalistic cousin to reach the meal inside. Pleistocene. The clam that bored into this ancient Florida coral became a fossil while resting in its burrow. Miocene Tampa, Florida. The tube inside this silicified Miocene coral from...

Facies

Geologists have a name for a part of a rock body that has such a relationship to other parts of a rock body. They call it a facies, and define a facies as the general appearance or nature of the one part as compared with the other parts. A series of modern-day facies could be created by instantly petrifying a part of Florida and entombing its denizens in sediments hardened into an unbroken sheet of rock of the same age. Part of the rock would represent a freshwater facies that might include...

Russell P MacFall Jay Wollin

We are the Ancients of the Earth, And in the morning of the times. NEW YORK CINCINNATI TORONTO LONDON MELBOURNE Dedicated to all the fossils yet unfound Van Nostrand Reinhold Company Regional Offices New York Cincinnati Chicago Millbrae Dallas Van Nostrand Reinhold Company International Offices London Toronto Melbourne Copyright 1972 by Litton Educational Publishing, Inc. Library of Congress Catalog Card Number 74-149259 ISBN 0-442-25060-6 cloth 0-442-25061-4 paper All rights reserved. No part...

The Carbon Method

For organic objects such as wood less than 40,000 years old, measurement is made of a certain form of carbon, Carbon-14. This radioactive form of carbon is the product of the action of cosmic rays in the upper air. It unites with oxygen to form radioactive carbon dioxide, which is taken up by living plants and then by animals that eat the plants. It is found in a constant proportion in all living tissues, decay of the radioactive carbon being balanced by constant replacement of cells. The...

The Nature Of Fossils

Simply defined, fossils are the remains or traces of organisms that lived prior to historic times. They most commonly preserve the shape or impression of the organism itself in rock, but they may be actual bone, or flesh preserved by freezing, or trails and other marks made by ancient animals. Today it is generally accepted that life has existed on our earth for more than two billion years, and that fossils are important clues to understanding its history and development. These facts seem...

Gravel Pits

Bison Teeth

In northern parts of the United States, gravel and sand pits operate in concentrations of glacial sands and pebbles such as kames, eskers, or well-sorted moraines. Elsewhere, and in some parts of the north as well, gravel pits usually lie in old riverbeds or near rivers. Many gravel pits operate in the Mississippi River. Gravel and sand pits are marked on topographic maps, or they can be found in telephone books under the listing Sand and Gravel. Usually, the gravel in the piles is sorted as to...

Geodes

Geodes are not sources of fossils, but some were originally fossils. A geode is a nodule of stone having a cavity lined with crystals or minerals. Once fossils, now geodes with hollow, quartz-lined centers. In becoming geodized, these unusual fossils grew greatly in size. This geodized crinoid stem was once the size of the large crinoid stem segment in the foreground. Mississippian Brown County, Indiana. Once fossils, now geodes with hollow, quartz-lined centers. In becoming geodized, these...

Sandstone

Austin Texas Fossil Clam Photos

Sandstone is just that, stone formed of cemented sand. It is usually too coarse to preserve delicate fossils, but many leaves lurk in the Dakota sandstone of Montana, and hundreds of brachiopods in the Oriskany sandstone of New York. Foraminifera and ostracods, little fossils that are themselves the size of sand grains, are abundant in marine sandstones of the Cenozoic era. Some marine sandstones include poorly preserved fossil shell molds. Water moved freely through these sands before they...

Conglomerate

Mixed Conglomerate

The coarsest-grained sedimentary rock is called conglomerate. It contains particles larger than sand, although it may contain finer particles, too. It looks very much like concrete. One variety is called pudding stone, from its resemblance to a pudding studded with fruit. In fact, the gastronomy-minded French use the word poudingue for conglomerate. The pebbles and rock fragments are usually cemented together by calcite or quartz. If the rock is made up of rounded pebbles, it is called...

Railroad Cuts

In the 1800s, railroad cuts were the source of many fossil collections. Roads went up and over the hills rather than through them, and few quarries were operating, so that railroad cuts created the only fresh exposures. A few cuts, mostly those through shales, are still productive. Many can be reached only after quite a bit of walking and are nearly vertical, making collecting difficult. Old cuts through famous fossil-bearing areas are still worth exploring, if for no other reason than that few...

Prehistoric Parts Collector

Shale is composed of clay, silt, or mud materials smaller in size than the sand and pebbles of sandstone and conglomerate. Clay is made up of microscopic particles of aluminum silicates, such as mica, and of clay minerals such as kaolin, with fine particles of feldspar, quartz, and iron oxides. Shale cemented by calcium carbonate is appropriately called limy shale, but if there is more calcium carbonate than clay, it is shaly limestone. Both will fizz when touched by a drop of hydrochloric...

Hog pens and animal burrows

Hillsides may have untold quantities of loose fossils in their soil, weathered from fossiliferous shales and limestones near the surface, but covered by grass and weeds. There is no more helpful animal than the hog for rooting out loose fossils in such places. A hog pen, though not the pleasantest place in which to collect, can contain lots of fossils. One Chicago area club has frequent field trips to a hog pen in Indiana that is paved with large crinoid stems and crinoid slabs showing sporadic...

Acids Type

Fossil Sandblasting

The gentle organic acids acetic and formic are used to clean fossils by slowly dissolving calcite limestone . Acetic acid gives vinegar its tart taste and smell. White vinegar is diluted acetic acid, formed naturally by fer mentation of alcohol. Formic acid, which causes the excruciating sting of an ant bite, is also found in some stinging plants. The two acids are quite similar in action but not in price. Acetic acid is far cheaper. Formic acid may be a bit gentler on some fossils, but not...

Coprolites

Coprolites

Coprolites are fossil excrement of anything from a mighty dinosaur to a fish or worm. Fish and shark coprolites are of particular interest because they often preserve tiny scales and teeth that reveal what the predator ate and what lived in the area where it dined. Such teeth and scales sometimes represent fish never found as fossils elsewhere. A fish coprolite nearly filling a concretion. Small bones, scales, and teeth from past meals are sometimes found in coprolites. Pennsylvanian Braidwood,...

The Antiquities

The basic law governing collecting on federally owned lands is the Antiquities Act of 1 9 0 6 U.S. Code Sec. 34 Statute L-225 . This provides that permits to examine ruins, excavate archeological sights, and to collect objects of antiquity or of historical or scientific interest on lands under their jurisdiction may be granted by the secretaries of the Interior, Agriculture, or the Army to institutions they deem properly qualified, provided that these activities are for the benefit of reputable...

Metal Mines

Lead Mines Galena

Dumps of iron, fluorite, lead, zinc, and other mines may contain fossils for the collector, because nearly all common metals are mined from fissures and cavities in limestones. Metal-mining areas are usually well known. The state Geological Survey can often supply a list of operating mines so can a university geologist. Mines, both operating and abandoned, are marked on topographic maps. Currently or recently operating mines are best for fossil hunting, as old dumps weather rapidly. As with all...

Ocean and Lake Beaches

White Mound Fossils Oklahoma

Hundreds of thousands of miles of coastline border the salt- and freshwater bodies of the United States. Few beaches are strictly sand, even the famous Florida and California beaches, and some are quite rocky. Fossils can be found in such gravel and rock accumulations, if they have been derived, at least in part, from a sedimentary rock. The fossils are usually poorly preserved, but the collecting is pleasant. As with river collecting, beach fossils are either waterworn pebbles or fresh...

Coal Mines

Underground Coal Mining Fossils

Among places where man has broken the earth for useful materials only quarries exceed coal mines in number and extent. The Midwest is particularly rich in bituminous coal mines, from central Illinois southeast into Indiana and Kentucky, and from mid-Iowa through western Missouri, eastern Kansas and on into Oklahoma and Texas. Another broad belt of fields rises in western Pennsylvania and spreads across West Virginia into eastern Kentucky and Tennessee down into Alabama. Colorado and Utah...

The Public Land Law Review Commission

The direction of federal thinking and probably of future law on the use of federal lands is contained in the report of the Public Land Law Review Commission, which made a five-year study of laws governing the third of the nation's area that is federally owned. Most of these lands are in the western states and Alaska. The Commission recommended that the United States retain these lands instead of trying to dispose of them as in the past, and it also recommended that a policy of classifying lands...

Waste Piles

Anatomie Sigillaria

The biggest collecting area at a strip mine is the badlands created by dumping of overburden. All rock layers seen in the working face can be found somewhere in these dumps. Gray shales are the commonest rocks here. They may contain plant fossils. Magnificent fronds of ferns preserved as black carbon films on the gray shale occur in the layers lying right above the coal. Such fossils must be collected by splitting blocks of the freshly mined material, because these gray shales collapse into...

How Fossils Are Formed

Original Preservation Fossil

Becoming a fossil is no easy adventure. In the more than two billion years of life on earth, an incalculable number of organisms have lived and died. If all had been preserved, our earth would have become nothing but a mass of fossils. Fortunately, most organisms have returned to the earth from which they came and left no fossil litter behind. A creature destined to become a fossil usually is one that possesses hard parts, such as a shell, horny armor like a crab, or bones that will resist the...

Ultrasonic Cleaners

Weathered matrix and clay often remain firmly wedged in fine openings in fossils, particularly such pore-bearing fossils as bryozoans and corals and around the compound eyes of trilobites. All the brushing in the world won't remove this material. But just a few minutes in an ultrasonic cleaner will remove this debris, and even some that appears firmly attached. Sand and shale that are not too firmly cemented can be removed neatly by placing the specimen in an ultrasonic cleaner tank for fifteen...

Preparing And Cleaning Fossils

Beer Can Plaster Paris

Few fossils are found so clean that they are fit to be placed in a collection without further work. Some need only a brushing some require painstaking treatment to remove rock that obscures the details of the fossil. Proper cleaning is important. Almost every day, an amateur collector brings a fossil to a museum to be identified. Too often a rare specimen has been damaged because its owner brushed varnish on it or destroyed fine detail by plunging the fossil...

Vibrotool

Several types of vibrating-point engravers are available the one most commonly used is the Vibro-Tool. All are priced around 10. The vibrator in such a tool causes a sharpened point to strike tiny blows many times a second, rather like a miniature jackhammer. An adjusting-screw controls the length of the stroke. The best model for fossil work has a chuck that will hold different points. Vibrating tools are useful to remove matrix rapidly from such specimens as these fossil clams. Vibrating...

Limestone

Common Fossils Limestone

Limestone is exceedingly common, is exposed over a wide area, and is abundantly fossiliferous. It has the further virtue of preserving its fossils A limestone composed principally of one type of fossil may be named after that fossil an example is this crinoidal limestone. Pennsylvanian San Saba, Texas. A limestone composed principally of one type of fossil may be named after that fossil an example is this crinoidal limestone. Pennsylvanian San Saba, Texas. with little crushing and in fine...

Quaternaryo

A chemical has recently appeared on the market that is far better than any of those formerly used. The product is Quaternary-O, which in the words of the manufacturer is a high molecular weight quaternary ammonium surface active agent. Translated, this is a super-detergent with superior wetting action. It is a thick, brownish goo resembling automobile lubrication grease. It dissolves slowly in hot water, but not in cold. The fossils are placed in a saucepan and covered with a solution of...

Fossils In Flint

Nodules of chert, an impure flint, are found in limestone formations. Chert is light-colored and opaque and breaks readily into sharp flakes. It is one of the materials the Indians used to make arrowheads and spearheads. It is found as fist-sized lumps scattered irregularly throughout some limestones, particularly those of Mississippian and Pennsylvanian age. After years of weathering, the nodules stand out as bumps and prickles on the strata, accumulate in the talus below the limestone bluff,...

Pits

Orbiculoides

The working face of the strip mine is a good place to start looking, as the various strata can be examined there. If any prove fossiliferous, like rock can be searched for later in the dump, where it is easier to break. It is also fruitful to ask permission to collect from newly exposed coal seams. Fossils may be locked in the coal or right on its surface. Petrified, often pyritized, logs and coal balls are found in the coal seams. The Coal Age trees did not have a well-defined woody structure...

Unusual fossil sites

There are other strange places to search for fossils but hardly common enough to deserve more than a passing mention. In dinosaur country from Colorado and Utah into Canada, occasional piles of gastroliths, or gizzard stones, are found. Some ancient lizards swallowed pebbles to help grind their food, and by definition these stones are fossils. On occasion the gas-troliths were themselves fossil pebbles. Nicely rounded and tumbled, these fossils are all of animals older than the Cretaceous or...

Hydrochloric Acid Fossils

Brachiopod Spines

Three other strong, cheap, and easily obtained acids are contained in this group hydrochloric, sulfuric, and nitric. The last two are dangerous to use and have no advantage in fossil use. Hydrochloric acid, also called muriatic acid, is an excellent solvent for any carbonate matrix, acting faster than organic acids though not as gently. Hydrochloric acid should be diluted to about a 10 percent solution, or weaker, for fine work. Cold water should be used, because mixing acid and water creates...

Interpreting the Topographic

Contour Interval Drawing

Interpreting the topographic map, like interpreting poetry, takes some practice and some imagination. The map's contour lines are like steps, with a fixed height of risers. The distance between the contour lines may be 20 feet or 100 feet the interval is chosen to present a readable representation of the detail involved on the particular map, and the interval is designated on the map. River valley and hills upper drawing and topographic map of same area lower drawing . The river flows into a...

Trace Fossils

Fossili Fucoides

These include trails and burrows and other fossil evidence of the activities of once-living creatures. A tidal mud flat at low tide is an amazing sight, covered with innumerable trails left by clams, crabs, and worms and speckled with holes that are the tops of burrows of a multitude of worms and clams. Should this area dry sufficiently to harden, the next tide might not destroy these markings but instead gently cover them with a layer of mud. When turned into rock and split apart, these layers...

Original Preservation

Bones, teeth, shells, and wood can be buried and remain chemically unchanged for millions of years. Most Miocene, Eocene, and Pleistocene shells such as those found in Maryland, Virginia, Florida, and California are essentially the same as when they were buried. Often the only clue to tell these 20-million-year-old shells from their modern counterparts is loss of color and luster. Many bones dredged up in midwestern gravel pits are little changed since they once held together ice-age animals....

Freezing

Frozen Mammoth

The best-preserved fossils are those of organisms that have been frozen quickly. Only a few species of not-very-old fossils have been so preserved to this day, notably some of the large Pleistocene mammoths that were mysteriously frozen while wandering about Siberia and Alaska about ten thousand years ago. These mammoths, still melting out of the permafrost, Frozen mammoth from Alaska in refrigerator case. Photo American Museum of Natural History, New York Frozen mammoth from Alaska in...

Casts and Molds

Example Molds Fossils

An organism, such as a shell, is buried in sediment, such as the ooze on the bottom of a sea. Water later dissolves the shell, leaving a hollow in the hardening sediment. The sediment becomes rock enclosing a cavity that exactly preserves the external pattern and shape of the shell. This is a mold. Sometimes a mold becomes filled with sediment or other mineral matter, producing an exact duplicate of the external pattern and shape of the shell. This is a cast from the mold. The pseudomorphs...

Power Drills

Dentists have found that one of their best tools is a high-speed power drill that will quickly and cleanly remove unwanted tooth material. Such a drill is equally effective with fossils. Unwanted matrix disappears quickly before a burr, tiny grinding wheel, or brush mounted in the chuck of a dental drill. A used dental drill can sometimes be purchased for a moderate sum, but never cheaply. Such a unit hanging above the workbench is a fine addition to fossil-cleaning tools. For a smaller sum a...

Sandblasting Fossils

Fossil Sandblasting

The sandblasting process, used to clean buildings and to etch tombstones, can also be used to clean fossils. A few years ago a small sandblaster that allowed localized and precise cutting was put on the market by Pennwalt-S.S. White Dental Products Division, 3 Parkway, Philadelphia, Pennsylvania 19102. It was designed to replace the dentists' drill. The idea was excellent, but the machine proved impractical because the abrasive clogged the fine orifice. Similar units are now available from the...

The Atomic Clock

Age determination by nuclear methods has been well described by Dr. Edward J. Olson of the Field Museum in the following quotation, which is used by permission. He wrote in the museum's Bulletin Suppose we had a large box with 6,400 green marbles in it. Then imagine that by some process in exactly one year half of the marbles had turned red. This leaves 3,200 green ones and 3,200 red ones. Suppose that in one year half of the remaining green ones become red, leaving 1,600 green and a total of...

Petrifaction

Fossilized Drift Wood

No category of fossil preservation is so misunderstood as petrifaction sometimes spelled petrification . Everyone has heard of petrified wood. The word petrified comes from the Greek word petros, meaning stone, and petrifaction literally means turned to stone. Unfortunately, many persons consider any fossil petrified. But strictly speaking, a fossil is petrified only when additional minerals have been deposited in pores or cavities in the fossil, or when the fossil is entirely replaced by other...

Treasures In The Dust

Cliffwood Beach Sand Stone Fossils

Some fishermen have all the luck like Francis Tully. Tully's favorite fishing spot is in the little lakes that punctuate the strip-coal-mining region not many miles south of his home in Lockport, Illinois, near Chicago. When the fish weren't biting, Tully passed the time by breaking open some of the rusty brown ironstone concretions that littered the huge dumps of waste rock. Occasionally he would find a fossil fern frond inside a concretion, and one day in the early 1960s he found his first...

Carbonization

Fossils Animals Resin

Carbonization, also known as distillation, is one process that preserves fossils of soft-bodied animals and leaves and stems of plants. Carbonization chemically alters the proteins and cellulose of tissues through degradation by bacteria, by chemical action, and by pressure and heat, until only carbon films remain. Other organic materials are dissipated as gases carbon dioxide, methane, hydrogen sulfide, and water vapor. For example, a thick, fleshy fern leaf of Pennsylvanian times falls into...

Shale Quarries

Iowa Limestone Quarries

Shale is sometimes quarried for the manufacture of bricks and ceramics. Some is mixed with ground limestone in making cement. For some reason, shale quarries are usually called clay pits or brick pits. They are so designated on geologic maps. Such pits can be located by inquiring of the Geological Surveys or by asking questions locally. They are rarely as deep as limestone quarries and are short-lived, designed to remove a thin layer of profitable clay near the surface before being abandoned....

Concretions

Leaf Fossils Ellsworth Kansas

Concretions are found in shale, occasionally in sandstone, and even in coal. If coal balls are described as concretions, coal may also be included. Concretions are most commonly composed of calcium carbonate or iron carbonate, although they may occur in sediments that are lacking in either carbonate. Their surface is usually curved and even spherical. They may be compared in form to a french-fried shrimp or onion ring. Such an object, dipped repeatedly in batter, builds around itself layer...

Microfossils

Leperditia

Collecting and preparing microfossils brings out the engraver in some collectors, for they must learn to handle, mount, and identify fossil organisms smaller than grains of salt. The world of the ultra-small has been extended to the tiniest fossils of all, the coccoliths, which become visible only with scanning by the electron microscope. These little shell-like fossils are so small that many species are invisible under a good optical microscope and require a magnification of 40,000 power to...

Drying

About the time the mammoths were freezing in the northlands, other vertebrates crawled into caves in southern desert regions and died. In this aseptic environment they became mummified. Bones and tissues of these desiccated denizens of the desert are preserved, although often they fall apart at the slightest touch. Even skin and hair retain their original color. Such fossils are the only accurate evidence available to the scientist trying to restore a bag of bones and give it the proper...