Lots of paleontology enthusiasts have heard of the Kettleman Hills, have in fact observed at any number of rock and fossil shows the magnificent Pliocene sand dollars and Pectens, in particular, that can be collected there. Here's an opportunity to take a cybervist visit to three specific fossil-bearing localities that yield many species of wonderfully preserved invertebrate fossil specimens. During the recent past, all three fossil-yielding areas were accessible, more or less, to private amateur paleontology enthusiasts--occurring as they did back on Chevron Corporation property, where advance permission had to be secured in writing from the oil company before a visit was made. Today, according to the most recent information available, the oil companies no longer allow private paleontology collectors to visit the localities, due to complicated legal liability issues.

Please Note: All fossils and on-site images figured and discussed here were snapped long before the recent oil company restrictions on private fossil hunters in the Kettleman Hills.

Back in 1940, the United States Geological Survey issued Professional Paper 195 by W.P. Woodring, Ralph Stewart and R.W. Richards, entitled: Geology of the Kettleman Hills Oil Field, with the subtitle Stratigraphy, Paleontology, and Structure. That's still pretty much the definitive geological and paleontological statement on the Kettleman Hills region, a classic work of science that continues to draw many paleontology enthusiasts/sleuths to university reference libraries all across America, seeking information on what kinds of fossils can be collected there--and just where such magnificently preserved material can be found. For that data, you need to thumb all the way to back of the paper, through all of those stunning black and white photographs of Kettleman Hills fossils--all of those perfectly preserved sand dollars and Pectens and clams and snails and such that truly boggle the mind and catch one's attention, holding it for lengthy periods of time, delaying the search for the exact localities from which the specimens came. When you finally get to the back of Professional Paper 195, one half expects to learn that most of the fossils likely came from no more than a dozen or so localities, 20 to 30 at most, perhaps (I am speaking from experience--this was my grand delusion, at least)--and so, it comes as a pleasant shock to learn that the Kettleman Hills, an area roughly 20 miles long by 4 miles wide situated some 80 miles northwest of Bakersfield in Kings County, California, contain 370 registered, distinct fossil localities in the Pliocene (4 to roughly 2 million years old) Tulare, San Joaquin and Etchegoin Formations (in descending order of geologic age--that is, from youngest to oldest)--a huge array of invertebrate, vertebrate and even floral fossil remains that includes Pectens (scallop shells), clams, gastropods, oysters, mussels, fish remains, land mammals, marine mammals, sand dollars, diatoms and even terrestrial plants, among others. Of course, many of those 370 specific fossil localities are no longer accessible (due to Oil Company policies/restrictions,), but there still remain many productive places where amateurs and professional paleontologists alike continue to collect loads of exquisitely preserved fossils from that remarkable series of Pliocene geologic rock deposits that record the ancient animal and plant life of the last great inland sea to cover the present-day Central Valley of California, a sea that at one time or another, during the Tertiary Period of the Cenozoic Era (65 to about 2 million years ago), stretched from Redding all the way south to the vicinity of Bakersfield. The three specific, accessible sites described here provide a representative sampling of the kinds of fossils to be found in the area, and each of them is loaded with abundant, well-preserved specimens.

Probably the best of the lot, in terms of overall variety of fossils, is what many paleontology enthusiasts refer to as the "Navy Pipeline" locality, or even "The Zone," in an affectionate, colloquial sense. The fish remains, Pectens, oysters and sand dollars found there occur in the Middle Pliocene San Joaquin Formation, which is roughly three million years old, and the Upper Pliocene Tulare Formation, around two to 1.8 million years ancient. It lies back in the Kettleman Hills on Chevron Oil Companies property, so permission, before the entire area was closed off to private collectors, had to be secured from the Chevron Companies branch office in Bakersfield, California, some 80 miles southeast of the Kettleman Hills, before any visit was made. Usually, though, that was not a problem. But, the bottom line here is: You certainly had to possess written approval from the Chevron folks, requesting formal permission to collect at the Navy Pipeline locality.

Averaging 10 to 20 feet in thickness, the fossiliferous horizon is a sequence of gray to tan silts and sands exposed for a length of a half to three-quarters of a mile--it is, in fact, an amazingly fossiliferous extension of the famous Pecten Zone in the Middle Pliocene San Joaquin Formation. And it is crammed almost everywhere one happens to look with perfectly preserved scallops , oysters and sand dollars, primarily, whose original shell material has been preserved intact. Here, one was advised to keep ones eyes open for the occasional beaver teeth, too, vertebrate remains that, invariably, while on Public Lands, one must leave alone, never collect except by formal written permission from the Bureau of Land Management; but there, you happened to collect on private property belonging to the Chevron Companies, and if you had successfully garnered the essential written documentation from their branch office in Bakersfield (let's hope that you had; one needed to carry the documentation with you at all times while on the oil company's land, or risk almost certain detention by the local law enforcement authorities while they decided whether to cite you for "simple" misdemeanor trespass, or perhaps even criminal trespass), you had secured the right to keep whatever fossils you happened to find, including vertebrate remains usually off-limits to unauthorized amateurs. The sand dollars measured, on average, from a half-inch to two inches in diameter, although many were quite minute--what you might call "sand pennies"--in the neighborhood of no more than a quarter-inch across. Yet, even such seemingly unpreservable, fragile remains had been faithfully kept whole for some three million years. All of the sand dollars are referable to one or two species of the genus Dendraster, primarily Dendraster coalingaensis. The scallop, or Pecten shells are striking, attractive specimens whose ribbed exteriors were very distinctive and identifiable in the sediments; most of them belong to the species Pecten coalingensis. An added collectng plus here was the fact that the majority of the fossils either weathered out of the San Joaquin Formation already intact, or could be dug out without any degree of pain or strain. All that's needed to put the finishing, cleaning touches on them was a gentle scrubbing in water with an old toothbrush.

In addition to the Pectens, oyster, sand dollars, beaver teeth teeth, another fossil type could be found in the same general area of the Navy Pipeline locality--fish remains. The specific horizon in which they occur lies within the Upper Pliocene Tulare Formation, which is about two million years old; geologists consider the Tulare to be a fresh to brackish water deposit that represents the final drying up of the great inland sea which, during Pliocene times, five to 1.8 million years ago, stretched from present-day Red Bluff south to the vicinity of Bakersfield. The Tulare Formation of the Kettleman Hills yields the largest fauna of fresh water Pliocene mollusks of any rock deposit on the West Coast. Some 33 species of pelecypods and gastropods have been described from it, although only a few have came from this particular spot near the Navy Pipeline/The Zone site. A second site in the Tulare, though, several miles south of the Navy Pipeline locality, yielded abundant well preserved fresh water mollusks.

But here at the Navy Pipeline site, fish remains were the thing--unusual fossils colloquially called "bulbous fish growths" by field geologists who've mapped the geology of the Kettleman Hills. These are the fossilized bony tumors which evidently afflicted many of the fish during Tulare times. Most of the fossil tumors are similar to observed types that attack the skeletons of modern weak-fish, cod (specifically the hakes), angel fishes and even catfish. No other fossil locality, save the Kettleman Hills, is known to yield these kinds of specimens. They are present in fair numbers in the tan silts and sands, most appearing as rounded, "bulbous" masses that reveal obvious bony structure on their worn exteriors. A few, though, show a definite resemblance in both shape and size to Brazil nuts. This "bulbous fish growth" zone is perhaps 30 feet thick at the most and trends generally south to southeast for a distance of approximately three-quarters of a mile. The fossilized bony tumors weather free from the easily eroded sediments and presented no difficulty to collect. Simply scooping them up when found, wrapping the specimens in tissue paper or paper towels and then storing them in a plastic bag usually protected all the fossil bony tumors quite nicely.

Much better preserved clams and snails from the Upper Pliocene Tulare Formation occurred several miles south of the Navy Pipeline/The Zone site in what local geologists call the Middle Dome district of the Kettleman Hills (the Navy Pipeline area lies in what's referred to as the North Dome, by the way). Here, innumerable tiny freshwater gastropods and pelecypods weathered whole, perfectly preserved. Because they were so exceedingly fragile, special care had to be taken to prevent them from getting damaged. It was best to place the mollusks in a plastic sandwich bag until you transported them home for a closer inspection. Also present here, in the more indurated (hardened) layers of sandstone, were relatively common specimens of brackish water mussels, most of which were in an excellent state of preservation. Almost all of the 33 species of freshwater mollusks identified from the Tulare Formation could be collected from this single locality. A distinctive feature of the assemblage was that, in general, the fossil clams and snails were very small, many no larger than a quarter-inch in length. For this reason, a good-quality hand lens of ten power or better was useful when studying the external details of your finds.

By the way, this is a pretty good place to mention that, when exploring for fossils in the Kettleman Hills, one couldn't even think of climbing fences to reach potential fossil-bearing places if you had failed to secure formal written permission from the Chevron Companies office in Bakersfield. One would face certain prosecution if one misbehaved here.

A third accessible, highly fossiliferous locality in the Kettleman Hills occurred several miles south of the Tulare locality; this one was within the Upper Mya Zone of the Middle Pliocene San Joaquin Formation, a place that yielded innumerable three million year old pelecypods, many with both valves preserved intact; it occurred in what's called the South Dome area of the Kettleman Hills. Consisting almost entirely of brackish water pelecypods belonging to Mya dickersoni and Macoma affinis, the fossils here were conspicuously abundant, although several zones reveal only fragmental material. Still, many nice specimens of clams with both valves preserved could be collected by using some extra care and patience. Although limited in aerial extent--the fossil-bearing layers ran for only about a tenth of a mile--this isolated exposure of San Joaquin Formation sediments in the Upper Mya Zone provided a maximum of clam-shell density, with Macoma and Mya liberally distributed throughout the brown clays.

And now for the obligatory words of caution: every individual who visited the central to southern San Joaquin Valley of California had to know something about what's informally called Valley Fever. This is a potentially serious illness caused by the inhalation of an infectious airborne fungus called Coccidioidomycosis, or "coccy" for short. The Kettleman Hills region, as well as the world-famous Middle Miocene Sharktooth Hill bone-bed several miles northeast of Bakersfield, on the eastern side of the Great Central Valley, contain extremely high concentrations of the spores which cause this disease. The spores lie dormant in the uncultivated soils until an unsuspecting individual breaths them into his or her lungs. There, the fungus may spring to life, as it prefers the moist, dark recesses of human lungs (in addition to many other kinds of critters' bodies, including cats, dogs, rodents, and even snakes), where it can multiply and be happy. Valley Fever fungal spores are endemic throughout most of Southern California, but they are particularly prevalent in the southern San Joaquin Valley, San Fernando Valley and portions of the the Mojave Desert. They are also know to occur in dangerous concentrations in a swath through central and southern Arizona, in extreme southern Nevada (around Las Vegas), in southern Utah (the Cedar City area) and in west Texas (El Paso and vicinity). Most cases of Valley Fever resemble a minor touch of the flu. In exceedingly rare cases, though, the disease ravages a particularly susceptible person, causing chills, high fever, unending fatigue, rapid weight loss, inflammation of the joints, pnueumonia, meningitis and even death. In deference to coccy, many visitors to the Kettleman Hills wore surgical masks or aspirators while stirring up the dust in search of fossil remains--to try to prevent the fungal spores from invading their lungs. Others didn't seem to bother; they just took their chances. But, the important point is this--every fossil collector who today visits the Kettleman Hills, or the southern San Joaquin Valley, in general, must be fully aware of the risks involved.

Although fossil collecting in the Kettleman Hills could be done year-round, a couple of seasons in California's Central Valley are notorious for, one, taxing bodily comfort and, two, interfering with driving safety. Summertimes, for example, are invariably ultrahot--downright savagely hot, as a matter of fact--with daytime temperatures more like extreme desert conditions than any other geographic comparison that comes to mind. And there was no shade to speak of in the hills, except for rare oven-tolerant shrubs maybe at most two feet high. These were fine for shading the head when lying flat on one's back, but rather puny for providing overall precautionary protection from the elements. And while winters are usually mild, with regular seasonal rainy patterns and tolerable temperatures, a particularly impenetrable fog inhabits the Great Central Valley during December and January--the infamous Tule Fog. It clamps down tight on the entire San Joaquin Valley region for days on end, at times reducing visibilities to zero. Needless to report, driving during the reign of the Tule Fog is hazardous and harrowing. And the Kettleman Hills, lying on the west side of the valley, do not seem to be exempt from these fogged conditions. Proceed at your own risk then.

When collecting in the Kettleman Hills, be sure to obey all the rules. Dont't even try to sneak onto Chevron Corporation oil lands to try to collect fossil remains from the ancient Pliocene-age geologic exposures. Private, amateur fossil hunters are no longer welcome there. The halycon days of glorious paleontological exploration have been long-concluded. Without a formal written permit to collect in the Kettleman Hills--and such a permit is invariably provided solely to trained men and woman of science, with at least a B.S. degree, or to personnel representing an acredited museum--fossil collecting anywhere in the Kettleman Hills is strictly forbidden. It is in fact universally verboten.