TODD
STEWART

Wheeler Peak, Great Basin National Park, Nevada, 2015

WPN-114 Prometheus |  Wheeler Peak, Nevada

38°59'08.92" N, 114°18'50.00" W

Bristlecone Pine (Pinus aristate Engelm.), the oldest living tree of verified age presently known, is restricted to numerous, rather isolated stands at higher altitudes in the southwestern United States. Stands occur from the Rocky Mountains, through the Colorado Plateau, to the western margin of the Great Basin. Studies in recent years (Schulman and Ferguson 1956, Schulman 1958) indicate maximum sampled tree ages of 700-800 years on Mt. Evans, Colorado; 1,500+ years on the San Francisco Peaks, Arizona; 3,100 years in the Schell Creek Range of eastern Nevada; and 4,600+ years in the White Mountains of eastern California. The last age, from a stand that includes a number of trees over 4,000 years old, is the oldest reported prior to 1965.

In 1963 and 1964, during studies of Recent (Little Ice Age) glaciation and nivation in the mountains of the southwestern United States, stands of bristlecone pine were encountered at several localities. Where feasible, older trees were cored or sectioned (1) to provide minimum absolute ages for glacial and periglacial features on which they are situated, and (2) to possibly provide dendroclimatic histories of the localities. A previously unstudied bristlecone pine stand on Wheeler Peak in easternmost Nevada was found to contain several trees well over 3,000 years old and one which is clearly about 4,900 years old.

To facilitate compilation of a long-term tree-ring chronology for the Wheeler Peak area, one of the larger living bristlecone pines was sectioned. This tree, WPN-114, grew at an altitude of 10,750 ft, on the gently sloping crest of a massive lateral moraine of Pleistocene age. The site was relatively stable during the lifetime of the tree, the only appreciable change being an accumulation of avalanche-transported debris so that the present ground surface is about 2 ft above the original base of the tree.

WPN-114 had a dead crown 17 ft high, a living shoot 11 ft high, and a 252-inch circumference 18 inches above the ground. The trunk was of the massive slab type. Bark was present along a single 19-inch wide, north-facing strip. Lateral die-back had left 92% of the circumference devoid of bark. The southfacing (uphill) side of the tree had been so deeply eroded that the pith was missing below a point 76 inches above the ground (100inches above the original base). A horizontal slab from the interval 18-30inches above the ground and a smaller piece including the pith 76 inches above the ground were cut from the tree, and a smoothly finished 2-piece transverse section was prepared. Within the radius sector present in the section, the growth layers, or rings, have a rather uncomplicated concentric arrangement. The tree-ring series contains both distinctively thin (microscopic) rings and difficult-to-count incomplete (locally absent) rings. The two parts of the section overlapped and were readily matched using a long ring sequence common to both. The derived radius measures 2,280 mm to the pith, 100 inches above the original base, and encompasses 4,844 counted rings. Mean ring width is 0.47 mm.

Under low power magnification, annual increments of earlywood and latewood were consistently discernible. Intra-annual (false) rings, which are not regarded as a serious problem among high-altitude bristlecone pines (Schulman and Ferguson 1956), presented no difficulty. It is probable, however, that not every year is represented in the ring series. The Wheeler Peak tree-ring chronology is not yet sufficiently well known to permit reliable detection of annual rings missing in this tree. Allowing for the likelihood of missing rings and for the 100-inch height of the innermost counted ring, it may be tentatively concluded that WPN-114 began growing about 4,900 years ago.

An Ancient Bristlecone Pine Stand in Eastern Nevada, Ecology, Donald R. Currey, 1965, B|RA 030120, B|RA 030920

Brent at Sandia Cave, Near Placitas, New Mexico, 2017

Sandia Man | Placitas, New Mexico

35°15'18.17" N, 106°24'21.50" W

The cave proved to be one of a group of five, located high in the limestone wall of Las Huertas Canyon in the Sandia Mountain Range just east of Albuquerque. Of the five holes in the limestone cliff in this place, only one is of any size or depth, and even this one cannot be described as pretentious. It was from this one, however, that the odds and ends of old civilization had come. We called the cave Sandia Cave, from the name of the mountains on whose edge it is located.

Sandia Cave may more properly be described as a tunnel leading back into the cliff some 200 yards. Throughout a considerable portion of its length, the debris and dust are piled almost to the roof. Locomotion past these strictured spots may be made only by slithering along on one’s stomach. The cave is exceedingly dry and redolent with the characteristic smell of bat guano and pack rat remains. It did not look particularly promising, because of its long slender form and its lack of roominess. 

As the scientific party had crawled and groveled almost to the end of the tunnel-like passageway, a flight of bats was disturbed from a chimney-like aperture that led upward from one of the galleries. With characteristic squeaks and the rustle of leathery wings, the bats rushed down the narrow passageway for the cave mouth. As they passed, the party involuntarily flinched close to the rocky walls to give them ample room. As they did so, one of the group felt beneath his hand, on a pile of debris, a curved bone. Even in the dark it felt unusual and important. 

With some excitement we made our way to the cave mouth, and there, in the light of a New Mexico afternoon, examined our find. It was indeed a bone, but certainly no ordinary one. It was shaped like the curved flat blade of a Turkish dagger. It was a core from the claw of a giant ground sloth—that lumbering animal so typical of late glacial times. It could be nothing else. This was a find indeed. If ground sloth remains were in the cave, and also human remains, we might find some evidence that men lived there at the same time as the sloths. We might yet find an American cave man. We did.

The Lost Americans, Frank C. Hibben, 1946, B|RA 031020

Crater Wall, Barringer Crater (Meteor Crater), Coconino County, Arizona, 2019

Barringer Crater (Meteor Crater) | Coconino County, Arizona

35°01'59.55" N, 111°01'17.78" W

An important part-in some respects the most important part-of the work of science is the explanation of the facts of Nature. The process through which natural phenomena are explained is called the method of hypotheses, and though it is familiar to most of my audience I shall nevertheless describe it briefly for the purpose of directing special attention to one of its factors. 

The hypothesis has been called a  scientific guess, and unless the title guess carries with it something of disrespect it is not inappropriate. When the investigator, having under consideration a fact or group of facts whose origin or cause is unknown, seeks to discover their origin, his first step is to make a guess. In other words, he frames a hypothesis or invents a tentative theory. Then he proceeds to test the hypothesis, and in planning a test he reasons in this way: If the phenomenon was really produced in the hypothetic manner, then it should possess, in addition to the features already observed, certain other specific features, and the discovery of these will serve to verify the hypothesis. Resuming its examination, he searches for these particular features. If they are found the theory is supported; and in case the features thus predicted and discovered are numerous and varied, the theory is accepted as satisfactory. But if the re-examination reveals features inconsistent with the tentative theory, the theory is thereby discredited, and the investigator proceeds to frame and test a new one. Thus, by a series of trials, inadequate explanations are one by one set aside, and eventually an explanation is discovered which satisfies all requirements. 

When the subject of study is one of wide interest it usually happens that several investigators cooperate in the invention and testing of hypotheses. Often each investigator will originate a hypothesis, and a series of rigorous tests will be applied through the endeavor of each one to establish his own by overthrowing all others. The different theories are rivals competing for ascendancy, and their authors are also rivals, ambitious for the credit of discovery. The personal factor thus introduced tends to bias the judgment and is to that extent unfavorable to the progress of science; but the conflict of theories, leading, as it eventually must, to the survival of the fittest, is advantageous. Fortunately, there is a mode of using hypotheses which regulates the personal factor without restricting the competition of theories, and this has found favor with the greatest investigators. It has recently been formulated and ably advocated by our fellow-member, Prof. T. C. Chamberlin, who calls it the method of multiple hypotheses.

To test this hypothesis of hypotheses I have for some years endeavored to analyze the methods employed by myself and some of my associates in geologic research, and this study has proved so interesting in connection with the investigation of a peculiar crater in Arizona…

The Origin of Hypotheses, Illustrated by the Discussion of a Topographic Problem, G. K. Gilbert, 1896, B|RA 031320, B|RA 031820