bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal age effects on Atlantic cod recruitment and implications for future population trajectories
Authors: Shelton Andrew Olaf , Hutchings Jeffrey A. , Waples Robin S. , Keith David M. , Akçakaya H. Resit , Dulvy Nicholas K.
Published: April 2015

Exploited fish populations frequently exhibit truncated age-structure. To address a basic question in fisheries science and conservation biology—how does age truncation affect population dynamics and productivity?—we explored the effect of age-structure on recruitment dynamics of ten stocks of Atlantic cod (Gadus morhua). Based on six alternative stock–recruitment relationships, we compared models that included and excluded maternal age-structure effects on recruitment. In all ten stocks, a recruitment model that included a maternal age-dependent effect was preferred over the standard Ricker model and in seven of the ten stocks, the preferred statistical model included a positive effect of either maternal age or mass on recruitment. Simulations comparing standard and maternal age dependent recruitment two decades into the future suggest that the inclusion of maternal age in recruitment models has little effect on projected biomasses. However, this similarity in biomass trajectory masked an increased sensitivity of populations with maternal age-dependent recruitment to stock age-structure. In particular, simulations with maternal age-dependent recruitment responded strongly to changes in fishing mortality on the oldest age classes, while simulations using standard recruitment models did not. Populations with maternal age-dependent recruitment can exhibit increased biomass catch even if fishing mortality on older individuals was reduced. Overall, simulations suggested that the influence of maternal age on population dynamics are more nuanced than suggested by previous research and indicate that careful consideration of the effects of age-structure on populations may lead to substantially different fisheries management reference points—particularly with respect to age-specific fishing mortality—than classical models. While these results suggest a link between maternal age and population productivity, future research requires the incorporation of biologically reasonable and empirically defensible mechanisms to clarify the effect of age on population dynamics.
A quantitative review of relationships between ecosystem services
Authors: Lee Heera , Lautenbach Sven
Published: April 2015

Ecosystems provide multiple ecosystem services to society. Ignoring the multi-functionality of land systems in natural resource management generates potentially trade-offs with respect to the provisioning of ecosystem services. Understanding relationships between ecosystem services can therefore help to minimize undesired trade-offs and enhance synergies. The research on relationships between ecosystem services has recently gained increasing attention in the scientific community. However, a synthesis on existing knowledge and knowledge gaps is missing so far. We analyzed 67 case studies that studied 476 pairwise combinations of ecosystem services. The relationships between these pairs of ecosystem services were classified into three categories: “trade-off”, “synergy” or “no-effect”. Most pairs of ecosystem services (74%) had a clear association with one category: the majority of case studies reported similar relationships for pairs of ecosystem services. A synergistic relationship was dominant between different regulating services and between different cultural services, whereas the relationship between regulating and provisioning services was trade-off dominated. Increases in cultural services did not influence provisioning services (”no-effect”). We further analyzed the pattern of relationships between ecosystem services across scales, land system archetypes and methods used to determine the relationship. Our analysis showed that the overall pattern of relationships between ecosystem services did not change significantly with scale and land system archetypes. However, some pairs of ecosystem services showed changes in relationships with scale. The choice of methods used to determine the relationship had an effect on the direction of the relationship: studies that employed correlation coefficients showed an increased probability to identify no-effect relationships, whereas descriptive methods had a higher probability of identifying trade-offs. The regional scale was the most commonly considered, and case studies were biased among different land system archetypes which might affect our ability to find the effect of scale or land system archetypes on the pattern of relationships. Our results provide helpful information of which services to include in ecosystem services assessments for the scientific community as well as for practitioners. Furthermore, they allow a first check if critical trade-offs have been considered in an analysis.
Isoform-level Ribosome Occupancy Estimation Guided by Transcript Abundance with Ribomap
Authors: Wang Hao , McManus Joel , Kingsford Carl
Published: April 2015

Ribosome profiling is a recently developed high-throughput sequencing technique that captures approximately 30 bp long ribosome-protected mRNA fragments during translation. Because of alternative splicing and repetitive sequences, a ribosome-protected read may map to many places in the transcriptome, leading to discarded or arbitrary mappings when standard approaches are used. We present a technique and software that addresses this problem by assigning reads to potential origins proportional to estimated transcript abundance. This yields a more accurate estimate of ribosome profiles compared with a naϊve mapping. Ribomap is available as open source athttp://www.cs.cmu.edu/∼ckingsf/software/ribomap.
Phenotypic Covariation And Morphological Diversification In The Ruminant Skull
Authors: Haber Annat
Published: April 2015

Differences among clades in their diversification patterns result from a combination of extrinsic and intrinsic factors. In this study I examined the role of intrinsic factors in the morphological diversification of ruminants in general, and in the differences between bovids and cervids in particular. Using skull morphology, which embodies many of the adaptations that distinguish bovids and cervids, I examined 132 of the 200 extant ruminant species. As a proxy for intrinsic constraints I quantified different aspects of the phenotypic covariation structure within species, and compared them with the among-species divergence patterns, using phylogenetic comparative methods. My results show that for most species, divergence is well aligned with their phenotypic covariance matrix, and those that are better aligned have diverged further away from their ancestor. Bovids have dispersed into a wider range of directions in morphospace than cervids, and their overall disparity is higher. This difference is best explained by the lower eccentricity of bovids’ within-species covariance matrices. These results are consistent with the role of intrinsic constraints in determining amount, range, and direction of dispersion, and demonstrate that intrinsic constraints can influence macroevolutionary patterns even as the covariance structure evolves.
Validity and reliability of bioelectrical impedance analysis to estimate body fat percentage against air displacement plethysmography and dual‐energy X‐ray absorptiometry
Authors: von Hurst Pamela R. , Walsh Daniel C.I. , Conlon Cathryn A. , Ingram Michelle , Kruger Rozanne , Stonehouse Welma
Published: April 2015

Air displacement plethysmography (ADP) and dual‐energy X‐ray absorptiometry (DXA) are well‐regarded methods for predicting body fat percentage (BF%). Bioelectrical impedance analysis (BIA) also predicts BF% and has distinct advantages in research settings.

Aim

To assess the validity of BIA against ADP and DXA to measure BF%, and to test the reliability of each method.

Methods

Adults (n = 166) with a wide range of body mass index (19–38 kg/m2) were tested twice during a 5‐day period. ADP was conducted in a BodPod (Life Measurement Inc, Concord, CA, USA); DXA measurements on a QDR Discovery A (Hologic) and BIA measurements used the InBody 230 (Biospace Ltd., Seoul, Korea). Agreement between measurements was analysed using t‐tests, effect size, linear regression models and method of triads (estimating true value).

Results

BIA showed excellent relative agreement to the estimated true value (ρ = 0.97 (0.96, 0.98)) and to ADP (R2 = 0.88) and DXA (R2 = 0.92), but wide limits of agreement (−4.25 to 8.37%). BIA underestimated BF% by 2%, across all values. DXA showed excellent relative agreement to the estimated true value (ρ = 0.97 (0.96, 0.98)) and with ADP (R2 = 0.92), good absolute agreement but wide limits of agreement (−6.13 to 6.91%) and under‐ and overestimation at high and low BF% levels, respectively. All methods showed excellent reliability with repeat measurements differing by less than 0.2% with very small 95% CIs.

Conclusions

BIA may be a valid method in research and population samples. All three methods showed excellent reliability.
Volcanic hazards in the Mexico City metropolitan area from eruptions at Popocatépetl, Nevado de Toluca, and Jocotitlán stratovolcanoes and monogenetic scoria cones in the Sierra Chichinautzin Volcanic Field
Authors: Siebe Claus , Macías José Luis
Published: April 2015

Tephrochronological studies carried out over the past decade in the area surrounding Mexico City have yielded a wealth of new radiocarbon ages from eruptions at Popocatépetl, Nevado de Toluca, and Jocotitlán stratovolcanoes and monogenetic scoria cones in the Sierra Chichinautzin Volcanic Field. These dates allow us to constrain the frequency and types of eruptions that have affected this area during the course of the past 25,000 yr. They have important implications for archaeology as well as future hazard evaluations.

Late Pleistocene and Holocene volcanic activities at the stratovolcanoes are characterized by recurrent cataclysmic Plinian eruptions of considerable magnitude. They have affected vast areas, including zones that today are occupied by large population centers at Puebla, Toluca, and Mexico City. During Holocene time, Nevado de Toluca and Jocotitlán have each experienced only one Plinian eruption, ca. 10,500 yr B.P. and 9700 yr B.P. respectively. During the same period of time, Popocatépetl had at least four such eruptions, ca. 8000, 5000, 2100, and 1100 yr B.P. Therefore, the recurrence interval for Plinian eruptions is less than 2000 yr in this region. The last two Plinian eruptions at Popocatépetl are of particular interest because they destroyed several human settlements in the Basin of Puebla. Evidence for these disasters stems from pottery shards and other artifacts covered by Plinian pumice falls, ash-flow deposits, and lahars on the plains to the east and northeast of the volcanic edifice.

Several monogenetic scoria cones located within the Sierra Chichinautzin Volcanic Field at the southern margin of Mexico City were also dated by the radiocarbon method in recent years. Most previous research in this area was concentrated on Xitle scoria cone, whose lavas destroyed and buried the pre-Hispanic town of Cuicuilco ca. 1665 ± 35 yr B.P. The new dates indicate that the recurrence interval for monogenetic eruptions in the close vicinity of Mexico City is also <2000 yr. The longest lava flow associated with a scoria cone was erupted by Guespalapa and reached 24 km from its source; total areas covered by lava flows from each monogenetic eruption typically range between 30 and 80 km2, and total erupted volumes range between 0.5 and 2 km3/cone. An average eruption rate for the entire Chichinautzin was estimated at ~0.5 km3/1000 yr. These findings are of great importance for archaeological as well as volcanic hazard studies in this heavily populated region.
Mountain-building theory
Authors: Mayo Dwight E.
Published: April 2015

Isostasy and the geosyncline are two major geological concepts that had their origins in the nineteenth century. Each is uniquely American in its origin, although a number of suggestions by Europeans triggered ideas in the minds of Americans. James Hall first published the basics of the geosyncline in 1859, although the concept was without its present name until that was provided later by James Dwight Dana. Isostasy-like generalizations began with J.F.W. Herschel in 1836, but it was not until 1889 that Clarence E. Dutton formally named the concept of isostasy. Isostasy and the geosyncline are closely related concepts in modern geological theory, and it is no surprise to find that they developed more or less concurrently and that certain individuals were involved in the development of each. Among geologists who either contributed to or critiqued the ideas, we find such familiar names as Hall, Dutton, Dana, T. Sterry Hunt, Joseph LeConte, G. K. Gilbert, William J. McGee and others. The development of isostasy and the geosyncline follows a process that is familiar in the history of science. Each was developed against the background of major philosophical arguments. Each was postulated minus much of the evidence required for a credible idea. Each attracted a number of proponents and detractors, and each had staying power sufficient to achieve general acceptance by the scientific community. At the present, against the backdrop of a major new theory system—plate tectonics—isostasy remains a useful and noncontroversial idea. The geosyncline, however, has a less solid future. Some geologists assert that it is no longer useful and should be junked, while others, by redefining the idea, continue to find it a major unifying concept.
The history of American theories of cave origin
Authors: Watson Richard A. , White William B.
Published: April 2015

In 1930, William Morris Davis published “Origin of Limestone Caverns” in the GSA Bulletin, initiating an episode of mistaken interpretation and resistance to field evidence almost unique in American geology. Davis proposed a two-cycle, deep-circulation theory of cave genesis by phreatic solution. J Harlan Bretz made heroic efforts to defend the theory, but geologic facts show it to be mostly wrong.

Davis ignored European literature, particularly the work of Alfred Grand and Jovan Cvijić whose empirical studies demonstrate that many caves are formed by solutional and mechanical action near and above the water table. Davis was misled by his lack of geochemistry and by fanciful maps of Mammoth Cave that show a labyrinth rather than the actual modified dendritic pattern of passages.

Among others, Claude A. Malott and James H. Gardner presented theories that displaced Davis' phreatic theory. In particular, Allyn C. Swinnerton developed a theory of temperate zone cave formation by flow along a seasonally fluctuating water table that is best supported by geologic evidence today. Recent work by Franz-Dieter Miotke, Arthur N. Palmer, and others relates episodes of cave formation to Pleistocene glacial periods.

Geochemical work initiated by Clifford A. Kaye and others caused a revolution in cave studies, and these data integrated with geologic, geomorphic, and hydrologic details by Derek C. Ford, Ralph O. Ewers, and others have led to sophisticated models of cave origin adaptable to all situations.

Some caves are formed by deep phreatic solution, although Carol A. Hill argues that in Carlsbad Caverns the active agent was sulfuric, not carbonic acid. Davis' prestige was so great, however, that his incorrect hypothetical model was an obstacle to the understanding of cave origin, and remains so today because of its continued uncritical incorporation in some elementary texts.
Glacial geology and the North American craton
Authors: Totten Stanley M. , White George W.
Published: April 2015

The craton was the focal point for the development of glacial geology in North America. Glacial deposits in the Ohio Valley were illustrated and described early in the century by Volney (1803, 1804), who, however, did not understand their origin and Drake (1815, 1825), who attributed the origin of erratics to icebergs. The iceberg hypothesis for the deposition of at least a part of the glacial drift persisted until late in the century.

The first glacial geologist in America was Charles Whittlesey who made early but significant studies in several states in the 1840s and 1850s. Whittelsey published the earliest maps and sections in America showing end moraines, kettle holes, and the glacial boundary. He was the first in America to classify drift, describe the “Forest Bed,” and trace drift in the subsurface.

In the 1860s and 1870s, the state geological surveys assumed a leadership role in glacial studies. Most notable of these was the Ohio Geological Survey directed by John Newberry, who was recognized as the leading glacial geologist of his time. An understanding of glacial lobes, glacial erosion of lake basins, moraines, multiple glaciation, and climatic change developed during this period.

In the 1880s, the U.S. Geological Survey under the guidance of T. C. Chamberlin established dominance in glacial studies of a regional nature. Chamberlin’s recognition that the glacial drift represented several glacial advances separated by warmer, nonglacial periods led to a formal classification for the North American Pleistocene.

By 1886, Chamberlin considered his phase of glacial studies essentially complete, and he assigned the responsibility of detailed moraine mapping to one of his assistants, Frank Leverett. Leverett proceeded to map in considerable detail the glacial drift and related geomorphic features of the Illinois and Erie lobes, covering an area extending from Iowa to New York. Leverett’s detailed mapping, keen observations, and ability to synthesize large volumes of data provided a fitting climax to nineteenth century glacial studies.
Development of ideas about the Canadian Shield
Authors: Wilson J. Tuzo
Published: April 2015

When the editors invited me to write they knew that I had begun field work on the Canadian Shield sixty years ago and had known many who had contributed to the great changes and developments in Precambrian geology. Unfortunately for the past seventeen years I have been fully engaged in administration and have not read the recent literature. This paper is thus a personal account and poorly documented. I’m not even sure which of the ideas advanced are accepted and which are still regarded as heretical.

In 1924, I started work in the woods, while still a schoolboy, and for much of the summers of 1926, 1927, and 1928 was field assistant to Noel E. Odell who had just returned from an expedition to Mount Everest on which he had been geologist and had made great efforts to find G. Mallory and A. Irvine, lost in their attempt to reach the summit. He was such an attractive teacher that on returning to the University of Toronto in 1927 I applied to transfer from a major in physics to one in geology. My professors were appalled. Physics was then in its heyday, but geology was held in very low esteem. Ernest Rutherford had compared it to postage-stamp collecting for it consisted of making maps by identifying and locating rocks and fossils. Instruments and methods were primitive and geology lacked general theories, which were scorned as “armchair geology.” This was in striking contrast to the precise theories common in physics, but few considered that Wegener’s concept of continents drifting slowly about had any merit, and no one, that I can recall, realized that therein lay the explanation for the lack of theories in geology.
Vestiges of a beginning
Authors: Cloud Preston
Published: April 2015

James Hutton’s proclamation that he saw “no vestige of a beginning” was an irresistible challenge. Geologists soon began searching downward through die “interminable greywackes” of Murchison for just such vestiges, especially of life. After Logan’s demonstration in the mid-1800s of thick sedimentary successions beneath fossiliferous Cambrian, Dawson described the generally discredited but perhaps in part biosedimentary Eozoon from rocks then thought to be among Canada’s most ancient. Stromatolites eventually became widely accepted as evidence of pre-Phanerozoic life. They are now recorded in carbonate rocks from perhaps 3.5 billion years (Gyr) ago onward. Many early reports also claimed the occurrence of Metazoa in rocks below the Cambrian. All reports turned out to be mistaken or dubious, however, except for those that now define the Ediacarian System which is basal to the Paleozoic Era and, in my view, a part of that era.

We see at last why searches for older Metazoa failed. The records of pre-Ediacarian life are paleomicrobiological, sedimentological, and biogeochemical. Microbial evidence is demonstrably present back to ~2 Gyr ago and still convincing back to ~ 2.8 Gyr ago. Stromatolites are presumptive evidence (not proof) for still older life. Geochemical interpretation is consistent with the presence of life back to the oldest known sediments. Metazoa began with the Ediacarian. They were the last main event of biological evolution. Thereafter, it involved primarily elaboration on the multicellular theme. The significant older records are cratonal, edited by the caprices of preservation, erosion, discovery, and subduction.
James Hall’s discovery of the craton
Authors: Dott Robert H.
Published: April 2015

Preeminent nineteenth century American geologist James Hall was not only one of the most competent and ambitious paleontologists and stratigraphers of his day, he also had a firsthand early grasp of midwestern as well as Appalachian geology. In 1841 he joined David Dale Owen for a tour of the Ohio Valley to see how far west the New York State stratigraphie divisions could be extended. He was warmly rewarded. With similar motivation, he also joined the Foster-Whitney-Whittlesey Lake Superior Survey of 1850-51. Then, when the New York legislature terminated his salary during one of its feuds with the irascible paleontologist, Hall accepted an invitation to organize a survey for the young state of Iowa in 1855-59; and in 1856 he assumed an advisory role to the embryonic Wisconsin Survey. He also became a consultant for several other states and had helped to instigate the first Hayden-Meek western Survey to the South Dakota Badlands (1853).

Hall’s unique acquaintance with cratonic as well as Appalachian stratigraphy and structure equipped him to recognize the fundamental differences between cratons and orogenic belts. The great thickness and structurally complex nature of Appalachian Paleozoic strata then led to development of his famous theory of mountain building, which was first expounded in the 1857 AAAS presidential address soon after his princi-pal midwestern experiences. Although Hall’s inferred simplisitc causal relationship between sediment thickness and mountain building proved wrong, the observation that thick strata are somehow associated with active tectonism was of fundamental importance and is still very much
E. O. Ulrich’s impact on American stratigraphy
Authors: Merk George
Published: April 2015

The controversial concepts of Edward Oscar Ulrich (1857–1944) dominated American stratigraphy during the first decades of this century. His U.S.G.S. mapping experience and extensive knowledge of the paleontology and stratigraphy of North America culminated in his masterwork: Revision of the Paleozoic Systems (1911) and several late papers (1916, 1920, 1924). The revision, which served as a guide to a generation of geologists, also contains Ulrich’s philosophy of correlation.

Application of his geological concepts to American stratigraphie successions led Ulrich to propose radical changes in existing classifications and correlations. Among his more controversial proposals were the creation of two new lower Paleozoic time stratigraphie units of systemic rank, the Ozarkian and the Canadian; a theory of oscillating troughs and barriers to explain the occurrence of the shelly carbonate and graptolitic shale facies in adjacent strike belts in the Appalachians; and the revision of the Croixan Series of the Upper Mississippi Valley. Each of these proposals was incorporated in various textbooks and correlation charts of the period.

However, as detailed stratigraphie studies in the Ozarks, the Upper Mississippi Valley, and in the Appalachians were completed, it was found that Ulrich’s concept of correlation was untenable and it was gradually replaced by one stressing facies relations. But, because of his authority, his disputative nature, and the tenacity with which he held his views, the development of American stratigraphy had been hampered.
The Iowa landscapes of Orestes St John
Authors: Prior Jean C. , Milligan Carolyn F.
Published: April 2015

Five original field sketches of the Iowa landscape, drawn in 1868 by Orestes H. St. John, were found in 1975 at the California Academy of Sciences in San Francisco. The pencil sketches were meticulously drawn, dated, and signed and included detailed landmark annotations. St. John, whose career paralleled significant developments within the field of geology, was Assistant Geologist of the Iowa Geological Survey from 1866 to 1869. Return of the sketches for the Survey archives revealed that these drawings correspond to five of the thirteen lithographs which illustrate the two-volume 1870 Report on the Geological Survey of the State of Iowa. The precise annotations enabled the authors to relocate and document the sites as they appear today. Revisiting these sites provided an opportunity to observe 110 years of historical change in land use from native prairie to intensive agriculture, urban growth, and woodland succession, as well as the effects of surface mining of mineral resources and the protection afforded to land in the public domain. Each site also had a significant geological context: the Missouri River valley and adjoining Loess Hills near Sioux City, the glacial moraines enclosing the Spirit Lake and West Okoboji Lake areas, the gypsum deposits near Fort Dodge, and the limestone resources exposed along the Des Moines River valley near Keosauqua. In relying on his own artistic skills to document these geological features and resources during this reconnaissance era of geological studies in Iowa, St. John joins the 19th Century tradition of documentary artists in America.
L. R. Wager and the geology of East Greenland
Authors: Brooks C. K.
Published: April 2015

Wager is most well-known for his work on the Skaergaard Intrusion of East Greenland, which was a milestone in the history of igneous petrology. It laid the founda-tion for a much better understanding of magmatic processes and for a multitude of investigations on similar bodies in other parts of the world. Less well known are Wager’s achievements in mapping an extensive area of East Greenland in which spectacular examples of Tertiary intrusive and extrusive rocks occur. This achievement, which was a major contribution to the understanding of the geological history of the North Atlantic region, was only possible because of Wager’s outstanding abilities as a mountaineer, polar explorer and leader, as demonstrated on his Greenland expeditions of 1930-31,1932,1935-36 and 1953, as well as by his feats on Mount Everest in 1933.

Wager’s interests extended to a wide range of traditional earth sciences, including tectonics, geomorphology, sedimentology and metamorphic processes. In addition, he played an innovative role in the fields of geochemistry and radiometric dating. It was his appreciation of the importance of laboratory techniques and innovations that set his work apart from that of most other field geologists of his time, and this, combined with his thoroughness, gave him an important place in the history of geological science.
Wrong for the right reasons
Authors: Laporte Léo F.
Published: April 2015

In the two decades preceding the establishment of plate tectonics theory, G. G. Simpson wrote a series of papers that refuted the paleobiogeographic evidence purportedly requiring direct continental connections. So cogent was his rebuttal that drift proponents thereafter downplayed the past distribution of fossils.

Simpson presented several different arguments. He restricted his discussion to Cenozoic mammals with whose evolutionary history he was most familiar; he challenged the accuracy of the proponents舗 data; he criticized their methodology, both with respect to its undue appeal to authority and its lack of parsimony; he used his own “coefficient of faunal similarity” to show that present-day mammal distributions on dispersed continents are comparable to those for Tertiary continents; and perhaps most effective was his statistical argument that trans-oceanic dispersal of organisms, while highly improbable for a single event, is practically certain given the many opportunities for such events over geologic time spans. Simpson舗s objections arose from his own independently developed theory of historical biogeography which, by relying on mobile organisms dispersing across stable continents, was fully adequate to explain the paleobiogeographic data. Simpson thus regarded both drift theory and trans-oceanic land-bridges neither sufficient nor necessary to account for those data.
Notes of a packer in the Idaho-Montana line survey summer of 1899
Authors: Brattain Ross R.
Published: April 2015

After I had finished my second year at Whitman (Whitman State College), Wink Worthington and I rode our bicycles to Spokane. It seems that Leslie (Leslie Brattain, Ross Brattain’s brother) was still reading law with Blake & Post or had gone into some office to get experience. Anyway he had living rooms and Wink and I stayed there while looking for a job. Wink read in the paper that there were some U.S.G.S. men at the Hotel Spokane who wanted to hire some young men to work for the summer on an Idaho-Montana line survey. College men who had some knowledge of such work preferred. He went to see them and took me. He had worked with his brother surveying and I had worked on a job of subdividing a township and also I had experience as a packer. We were both hired. The engineer in charge was a Mr. Rayburn and the head man to start us off was a Mr. Gannett. (Henry Gannett, illustrious geographer and topographic engineer). We were given tickets and told to report at Heron, Montana, which was the closest railroad point to our point of departure. All we had to take with us were clothes to wear on the job, everything else was furnished by the U.S.G.S. We reported as directed and found Mr. Rayburn and Mr. Gannett there and a packer by the name of McQuirck and with him ten pack mules with Mexican aparejos and two saddle horses with men’s saddles, one of which was white and the bell mare of the pack train.
Contributions of the state geological surveys
Authors: Oakeshott Gordon B.
Published: April 2015

At the opening of the nineteenth century, almost none of the sciences were taught in educational institutions. A point of great importance to the early development of geology was the appointment of Benjamin Silliman as professor of chemistry and natural science at Yale College in 1802. Silliman’s students initiated a number of state geological surveys in the 1820s and 1830s, starting with North Carolina in 1823, which made major contributions to geological understanding, principles, and applications. There are now 51 state geological surveys—including Puerto Rico—each with staffs ranging from a single “State Geologist” to over 200 people. Of the original state surveys only the California survey, founded in 1880, has survived to the present day with continuous funding. Alabama, Alaska, California, Illinois, Indiana, Kansas, Oklahoma, and Texas maintain their positions as the largest of the state surveys. The U.S. Geological Survey, which does work in all states and in foreign territory, was founded in 1879.

From their beginnings, through the 1950s, state activities were strongly oriented to mineral-resources studies, geologic mapping, and public information. The 1960s saw the burgeoning of concerns for the “environmental” (and engineering) applications of geology.

The decade of the 1970s witnessed greatly-increased emphasis on engineering and environmental geology, especially investigations of “geologic hazards”; development of mineral resources, with due regard to the disposal of wastes, and other environmental concerns; and a renewed consciousness of the importance of public and political participation. Budgets and personnel of the state surveys approximately doubled during the decade. This trend has continued into the '80s, but, lately, growth has been somewhat inhibited by budget restrictions and inflation.

The state geological surveys are economically and politically responsive to state authority and therefore have developed a unique capability to serve directly the geological needs of the public.
A history of geology at the University of Pennsylvania
Authors: Faul Carol
Published: April 2015

A survey of the study of geology and geologists at the University of Pennsylvania up to the end of the nineteenth century provides a kaleidoscope of the development of American geology. The topics emphasized and the work of Penn faculty elsewhere show the evolution of state and national surveys and organizations.

Geology at the University of Pennsylvania began in 1749 when Benjamin Franklin aided in establishing a formal academy of study. At first, geology was taught peripherally to other fields, mainly by botanists, chemists, and physicians. There was discussion about a professorship of geology and mineralogy in 1816 but the subject was diffused among other professorships. In 1835 geology was formally established at the University of Pennsylvania and Henry Darwin Rogers was appointed Professor of Geology and Mineralogy.

A succession of geologist-administrators dominated Penn geology through much of the nineteenth century; among them, Alexander D. Bache, who left Penn to head the U.S. Coast Survey in 1843; Henry Darwin Rogers, director of the New Jersey Geological Survey and the First Geological Survey of Pennsylvania while a Penn professor; Ferdinand V. Hayden, director of the U.S. Geological and Geographical Survey of the Territories; and J. Peter Lesley, director of the Second Geological Survey of Pennsylvania. Joseph Leidy and Edward D. Cope were renowned vertebrate paleontologists who worked on Hayden’s Survey material.

Beginning around the turn of the century, students succeeded their teachers as heads of the Department and geology declined, with intermittent, unsuccessful attempts to revive it, until 1963, when the present reconstruction began. It is a task which Henry Faul, one of its architects, estimated would take 25 years to complete.
The early development of archaeological geology in North America
Authors: Gifford John A. , Rapp George
Published: April 2015

As in Europe, in North America the origins of archaeological geology stemmed from discoveries of artifacts and fossil mammal bones together, and the bearing of such associations on the antiquity of humans in the New World. After 1870 the expansion of American and Canadian federal government surveys into the western portions of North America fostered a tradition of geologists undertaking archaeological field studies as a contingent part of their primary work. This informal collaboration ended around the turn of the century (with a few notable exceptions), as both sciences crystallized into more strictly defined fields. Debate over the antiquity of humans in the New World continued into the 1920s, only ending when definitive geological and paleontological evidence was presented to date artifacts to the end of the last glaciation.

While the initial link between archaeology and geology in North America concerned the question of human entry, other fields of research during the late nineteenth and early twentieth century included petrography of stone artifacts as a means of determining their origin, and geomorphic studies of archaeological sites as an indication of landform modification and environmental change. From such “informal” interdisciplinary research, often accomplished by individual initiative, the connection between geology and archaeology grew, slowly in the pre-World-War-II period and almost explosively in postwar decades due to a general realization by archaeologists of the natural environment’s importance in understanding cultural development.
Application as stimulus in geology
Authors: Jordan William M.
Published: April 2015

The Geological Society of America was conceived in 1881 and bom in 1888 as part of an era of unprecedented mineral-based prosperity that has continued, with wartime and business cycle fluctuations, to the present. From its earliest days, geology and its practical applications, particularly industrial, have been intimately connected. This paper examines the mutual relationship of practical need and geology during the first halfcentury of the GSA, focusing particularly on how practical needs stimulated theoretical developments. Three specific examples of this relationship are given: G. K. Gilbert’s studies of hydraulic mining-induced aggradation of streams in California; the influence of iron and other mining in the Lake Superior region on the early development of Precambrian stratigraphy; and geology’s rediscovery of the concept of facies as a consequence of exploration for coal in Utah and the search for petroleum in the Permian of West Texas.
Seismic exploration of the crust and upper mantle of the Basin and Range province
Authors: Pakiser L. C.
Published: April 2015

The fundamental features of the seismic-velocity structure of the crust of the Basin and Range province have been known for 30 years. Tatel and Tuve (1955) expressed surprise in finding that the crust is only 28–34 km thick in the Basin and Range/Colorado Plateau transition zone of Arizona, New Mexico, and Utah. From isostatic considerations they had expected the crust of this elevated region to be about 70 km thick. Carder and Bailey (1958) obtained similar results in the Basin and Range province in the vicinity of the Nevada Test Site. Later, Press (1960), Berg and others (1960), and Diment and others (1961) discovered the characteristic low velocity of the upper mantle of the province, although they regarded the 7.6–7.8 km/sec velocities they found at depths of 24–28 km as possibly too low for the upper mantle. Nevertheless, the unexpectedly thin crust and low-velocity upper mantle have been accepted by most investigators as characteristic features of the Basin and Range province since U.S. Geological Survey seismic teams demonstrated that the discontinuity below which the velocity is about 7.8 km/sec is the most prominent one in the province and argued that it should be regarded as the Mohorovičé discontinuity (Pakiser, 1963).

Our knowledge of the gross features of the crustal and upper-mantle structure of the Basin and Range province has changed little in the past 20 years, but many important details have been added. Major problems, however, remain to be resolved. Reexamination of the evidence for extremely low upper-mantle velocities in the vicinity of the Wasatch front (Smith, 1978) suggests that velocities there may not be very different from those in other parts of the province. New, more nearly definitive seismic-refraction and -reflection experiments and reanalysis of existing data using new analytical techniques will be required to resolve such problems.
A basement of melanges
Authors: Hsü Kenneth J.
Published: April 2015

The Franciscan of the California Coast Ranges was considered a lithostratigraphic unit (a formation or group of formations) for more than a century. Normal stratigraphical methodology was practised, and few questioned the applicability of the laws of superposition, lateral continuity, and paleontological dating. Despite evidence to the contrary, researchers portrayed deformation of coherent strata. Metamorphic conditions were deduced on the basis of presumed field relations, and the geosynclinal theory of mountain building was the paradigm. A subjective choice of data allowed researchers to fit the Franciscan into a straight-jacket, and for many years it was described as a Late Jurassic Tithonian formation, deposited in a eugeosyncline on the western margin of the North American continent after the Nevadan Orogeny.

The classical model failed to take into account a number of key observations that challenged accepted beliefs. Micropaleontological evidence for the Cretaceous age of some Franciscan rocks was known but not taken seriously. Finally, however, the discovery of an ammonite of undoubted Cretaceous age in a Franciscan sandstone at the type locality led to a crisis. It became impossible to ignore mounting evidence that the Franciscan contains rocks coeval to the Great Valley Sequence, which ranges in age from Tithonian to Late Cretaceous, despite the fact that rocks of typical Franciscan lithology (e.g., ophiolites) underlie the Knoxville and should therefore be older than the Great Valley Sequence.

The application of the mélange concept and the assumption of underthrusting resolved the Franciscan-Knoxville Paradox, and resulted in a revolutionary change in our thinking on Franciscan geology. At about the same time, a new paradigm in geology, the new plate-tectonic theory, was introduced. With plate tectonics, crises could be overcome, contradictions eliminated, and a period of “normal science” could prevail.

Franciscan research went through five stages: 1) random observations; 2) synthesis; 3) crisis; 4) revolution, or overthrow of the old paradigm and establishment of the new; and 5) mopping up. A history of the process illustrates the theory of scientific revolution advocated by Thomas Kuhn.
The Coon Butte Crater controversy
Authors: Drake Ellen T.
Published: April 2015

G. K. Gilbert's (1891) first assessment of the crater at Coon Butte, Arizona (now called Meteor Crater), was that it was caused by a meteorite impact. His classical paper The Moon's Face (1893) eloquently argued for the impact hypothesis to explain lunar craters. But by 1896 he had changed his mind on the Coon Butte Crater, as he could not find the “buried star,” even though several tons of meteoritic material had been found in the area. The steam explosion explanation, suggested to him by Willard D. Johnson and tentatively adopted by Gilbert, then became the accepted hypothesis for the origin of Coon Butte Crater among most geologists. In spite of a great deal of evidence for the impact idea, the steam explosion explanation, with the exception of a few notable individuals, took root in the geological community, much to the frustration of D. M. Barringer. The latter insisted on the existence of the “main mass” of the meteorite and spent a lifetime and fortune attempting to prove the impact origin of the crater by looking for the meteoritic body. He also had visions of a lucrative mining adventure. Barringer opposed G. P. Merrill, a distinguished scientist within the geological community, who supported the impact idea but explained the absence of a “main mass” of meteoritic material by its volatilization. The modem explanation for the creation of the crater is by shock waves produced from the dissipation of kinetic energy of the meteorite travelling at hypervelocity.

Several reasons might explain the long delay in acceptance of the impact hypothesis: (1) in the absence of more evidence, the geological community naturally followed the lead of the much-admired Gilbert; (2) to the geologists, Barringer and his associates were outsiders, rich and respected men in other fields and in industry, but not in geology and therefore could be ignored; (3) Barringer was “ahead of his time,” and therefore could not expect much support from his contemporaries. The reasons were probably multiple and complex and may involve fundamental philosophical concepts. For example, as Eugene Shoemaker (1984) suggested, geologists were so imbued with Lyellian uniformitarianism that they could not accept a catastrophic explanation, i.e., the fall of an extra-terrestrial object causing the creation of a terrestrial feature. It is not clear, however, that any one answer explains the puzzle. The Coon Butte Crater controversy also tests two other ideas much touted by geologists, the principle of multiple working hypotheses and the idea of tolerance for unorthodoxy in science. Both concepts seemed to have failed the test.
Development of quantitative geomorphology
Authors: Morisawa Marie
Published: April 2015

Despite numerous precursors, real quantification in geomorphology did not take hold until after Horton's (1945) paper outlining a new approach to the study of drainage basins. The use of quantitative methods in landform analysis has varied for different geomorphic processes.

Quantitative studies in weathering have been done mostly in the fields of geochemistry, pedology, and soil mechanics. Little has been done to quantify weathering forms. Quantitative analyses on slopes and mass movements have included both processes and morphology, leading to geometric and mathematical models. In contrast, quantitative analyses of arid regions and aeolian forms and processes are immature and tentative. Although great strides have been taken in using physics and mathematics for understanding glacier flow, little has been done on morphometry of glacial landforms. Progress in quantitative coastal research has been most rapid since World War II, although the mathematical basis for understanding coastal processes was laid in the 19th century. As a result of Horton's (1945) provocative study, fluvial geommorphology has perhaps made the most advances in quantitative analyses in geomorphology.

The infusion of ideas from physics, chemistry, biology, engineering, pedology, soil mechanics, hydraulics, hydrology, and geography and the application of statistics and mathematics in analysis accomplished the quantitative revolution. In addition to changing techniques of analysis, quantification has altered the fundamental approach to the study of landforms and affected basic concepts. The dynamic approach (Strahler, 1952) became focused on process and mechanics rather than history and description. Landscape units are treated as open systems in equilibrium where any change in the system causes an adjustment to offset effects of the change.

Electronic instrumentation, remote sensing, and advanced methods of data processing and storage by high-tech computers will open even more vistas for exploration by quantitative geomorphologists of the future.
Canadian Shield
Authors: Shilts William W. , Aylsworth Janice M. , Kaszycki Christine A. , Klassen Rodney A.
Published: April 2015

The Canadian Shield* (Fig. 1) is a geologically complex terrain that makes up about one-third of the North American landmass. Its rocks were deposited, formed, and deformed over a time span encompassing about three-quarters of the earth’s known geologic history. Consequently, it includes lithologies, structural elements, and topography as varied as those found on the North American continent as a whole. Because of the complexity of geomorphic features that reflect this geologic diversity, we have decided to focus this chapter on the most obvious geomorphologic elements of its modern landscape, the various landforms produced by the latest geologic events to affect the area, the Pleistocene glaciation. Virtually all of the distinctive landscape elements commonly associated with the Canadian Shield were formed or noticeably modified as a result of the passage of glaciers that coalesced to form the last great continental ice mass, the Laurentide Ice Sheet (Prest, 1970).

Before discussing the glacial geomorphology of the Shield, it is appropriate to make some general observations of the geologic factors that have influenced the nature and distribution of glacial landforms and sediments. Because of the antiquity of the rocks that comprise this “stable” core of the continent, original lithologies have been modified by numerous orogenic and metamorphic events as the earth’s crust evolved and as crustal elements shifted through the agency of plate tectonics. The composition of the oldest rocks, in fact, reflects both sedimentation in a primitive, pre-oxygen atmosphere and igneous events that took place as the