Writing PD: accounting for socially-engaged research

As participants in participatory process, PD academics report on the practices and outcomes of their work and thereby shape what is known of individual projects and the wider field of participatory design. At present, there is a dominant form for this reporting, led by academic publishing models. Yet, the politics of describing others has received little discussion. Our field brings diverging sensibilities to co-design, conducting experiments and asking what participation means in different contexts. How do we match this ingenuity in designing with ingenuity of reporting? Should designers, researchers and other participants all be writing up participatory work, using more novel and tailored approaches? Should we write more open and playful collaborative texts? Within some academic discourse, considerable value is placed on reflexivity, positionality, inclusivity and auto-ethnography as part of reflecting. Yet, PD spends no time in discussing its written outputs. Drawing on the results of a PDC’16 workshop, I encourage us to challenge this silence and discuss “Writing PD”

Proximal Air-Fall Deposits of Eruptions Between May 24 and August 7, 1980 -- Stratigraphy and Field Sedimentology. U.S. Department of the Interior, Geological Survey

During each of the magmatic eruptions of Mount St. Helens on May 25, June 12, and August 7, a vertical eruptive column rose intermittently to altitudes of 12-15 km, from which pumice, lithic fragments, and crystals settled downwind in lobes that generally become thinner and finer away from the volcano. Each ejecta lobe is asymmetric according to several criteria, including (1) the axes of maximum thickness and of maximum pumice size are not midway between the two margins of the lobe, (2) the axis of maximum pumice size does not correspond to the axis of thickness, and (3) the median size of particles grades through several grain-size intervals from one lateral margin to the other. The fining in grain size across the lobe is due to the rotation of wind directions with altitude, so material falling from a high-level airborne plume is winnowed as it falls through transverse low-level winds. Wind directions that rotate clockwise with increasing altitude effect an air-fall lobe whose axis of maximum coarseness is clockwise of the axis of maximum thickness; wind directions that rotate counterclockwise with increasing altitude effect an air-fall lobe whose trend of maximum coarseness is counterclockwise of the axis of maximum thickness. The thickness of air-fall deposits from eruptions on May 25 through August 7 range variously from one-third to one-fortieth that of the May 18 air-fall deposit at a given distance from the volcano. The post-May 18 deposits are an order of magnitude thinner than Mount St. Helens pumice layer T (A.D. 1800) and two orders of magnitude thinner than Mount St. Helens pumice layer Yn (3400 yr B.P.), which is similar in thickness to the most voluminous air-fall deposits of other Cascade Range volcanoes. The maximum size of pumice within the May 18 air-fall lobe is 5-10 times that of the post-May 18 lobes. The overlapping air-fall lobes of May 25, June 12, July 22, and August 7 form a stratigraphic layer that in most places is indivisible into deposits of the separate eruptions

Decentring watersheds and decolonising watershed governance: Towards an ecocultural politics of scale in the Klamath Basin

The watershed has long captured political and scientific imaginations and served as a primary sociospatial unit of water governance and ecosystem restoration. However, uncritically deploying watersheds for collaborative environmental governance in indigenous territories may inappropriately frame sociocultural, political-economic, and ecological processes, and overlook questions related to power and scale. We analyse how members of the Karuk Tribe’s Department of Natural Resources have leveraged and critiqued collaborative watershed governance initiatives to push for 'ecocultural revitalisation' – the linked processes of ecosystem repair and cultural revitalisation – in Karuk Aboriginal Territory in the Klamath River Basin. We argue for decentring watersheds in relation to other socio-spatial formations that are generated through indigenous-led processes and grounded in indigenous knowledge and values. We explore two scalar frameworks – firesheds and foodsheds – that are emerging as alternatives to the watershed for collaborative natural resources management, and consider their implications for Karuk ecocultural revitalisation. We attempt to bring watersheds, firesheds, and foodsheds together through an ecocultural approach to scale in which water is one among many cultural and natural resources that are interconnected and managed across multiple socio-spatial formations and temporal ranges. We emphasise 'decolonising scale' to foreground indigenous knowledge and to support indigenous sovereignty and self-determination

Areal Distribution, Thickness, Mass, Volume, and Grain Size of Air-Fall Ash from the Six Major Eruptions of 1980

The airborne-ash plume front from the Mount St. Helens eruption of May 18 advanced rapidly to the northeast at an average velocity of about 250 km/hr during the first 13 min after eruption. It then traveled to the east-northeast within a high-velocity wind layer at altitudes of 10-13 km at an average velocity of about 100 km/hr over the first 1,000 km. Beyond about 60 km, the thickest ash fall was east of the volcano in Washington, northern Idaho, and western Montana. A distal thickness maximum near Ritzville, Wash., is due to a combination of factors: (1) crude sorting within the vertical eruptive column, (2) eruption of finer ash above the high-velocity wind layer at altitudes of 10-13 km, and (3) settling of ash through and below that layer. Isopach maps for the May 25, June 12, August 7, and October 16-18 eruptions show distal thickness maximums similar to that of May 18. A four-unit tephra stratigraphy formed by the May 18 air fall within proximal areas east of the volcano changes to three units, two units, and one unit at progressively greater distances downwind. Much of the deposits beyond 200 km from the volcano has two units. A lower thin dark lithic ash is inferred to represent products that disintegrated from the volcano\u27s summit in the initial part of the eruption and early juvenile pumice and glass. An upper, thicker, light-gray ash rich in pumice and volcanic-glass shards represents the later voluminous eruption of juvenile magma. The axis of the dark-ash lobe in eastern Washington and norther Idaho is south of the axis of the light-gray ash lobe because the high-velocity wind layer shifted northward during the eruption. The areal distribution of ash on the ground is offset to the north relative to the mapped position of the airborne-ash plume, because the winds below the high-velocity wind layer were more northward. Except for the distal thickness near Ritzville, Wash., mass per area, thickness, and bulk density of the May 18 ash decrease downwind, because larger grains and heavier lithic and crystal grains settled out closer to the volcano than did the lighter pumice and glass shards. A minimum volume of 1.1 km3 of uncompacted tephra is estimated for the May 18 eruption; this volume is equivalent to about 0.20-0.25 km3 of solid rock, assuming an average density of between 2.0 and 2.6 g/cm3 for magma and summit rocks. The estimated total mass from the May 18 eruption is 4.9 x 1014 g, and the average uncompacted bulk density for downwind ash is 0.45 g/cm3. Masses and volumes for the May 24 and June 12 eruptions are an order of magnitude smaller than those of May 18, but average bulk densities are higher (about 1.00 and 1.25), owing to compaction by rain that fell during or shortly after the two eruptions. Volume and mass of the July 22 eruption are two orders of magnitude smaller than those of May 18, and those of the August 7 and October 16-18 eruptions are three orders of magnitude smaller. The eruption of May 18, however, is smaller than five of the last major eruptions of Mount St. Helens in terms of volume of air-fall tephra produced, but probably is intermediate if the directed-blast deposit is included with the air-fall tephra

THE STYLE OF LATE CENOZOIC DEFORMATION AT THE EASTERN FRONT OF THE CALIFORNIA COAST RANGES

The 1983 Coalinga earthquake occurred at the eastern boundary of the California Coast Ranges in response to northeast directed thrusting. Such movements over the past 2 Ma have produced Coalinga anticline by folding above the blind eastern tip of the Coalinga thrust zone. The 600-km length of the Coast Ranges boundary shares a common structural setting that involves westward upturn of Cenozoic and Cretaceou strata at the eastern front of the Coast Ranges and a major, southwest facing step in the basement surface beneath the western Great Valley. Like Coalinga anticline, Pliocene and Quaternary folding and faulting along the rest of the boundary also result from northeast-southwest compression acting nearly perpendicular to the strike of the San Andreas fault. We suggest that much of this deformation is related to active thrusts beneath the eastern Coast Ranges. The step in the basement surface beneath the Great Valley seems to have controlled the distribution of this deformation and the shape of the Coast Ranges boundary

The Masaya Triple Layer: a 2100 year old basaltic multi-episodic Plinian eruption from the Masaya Caldera Complex (Nicaragua)

The Masaya Caldera Complex has been the site of three highly explosive basaltic eruptions within the last six thousand years. A Plinian eruption ca. 2 ka ago formed the widespread deposits of the Masaya Triple Layer. We distinguish two facies within the Masaya Triple Layer from each other: La Concepción facies to the south and Managua facies to the northwest. These two facies were previously treated as two separated deposits (La Concepción Tephra and the Masaya Triple Layer of Pérez and Freundt, 2006) because of their distinct regional distribution and internal architectures. However, chemical compositions of bulk rock, matrix and inclusion glasses and mineral phases demonstrate that they are the product of a single basaltic magma batch. Additionally, a marker bed containing fluidal-shaped vesicular lapilli allowed us to make a plausible correlation between the two facies, also supported by consistent lateral changes in lithologic structure and composition, thickness and grain size. We distinguish 10 main subunits of the Masaya Triple Layer (I to X), with bulk volumes ranging between 0.02 and 0.22 km3, adding up to 0.86 km3 (0.4 km3 DRE) for the entire deposit. Distal deposits identified in two cores drilled offshore Nicaragua, at a distance of ∼ 170 km from the Masaya Caldera Complex, increase the total tephra volume to 3.4 km3 or ∼ 1.8 km3 DRE of erupted basaltic magma. Isopleth data of five major fallout subunits indicate mass discharges of 106 to 108 kg/s and eruption columns of 21 to 32 km height, affected by wind speeds of < 2 m/s to ∼ 20 m/s which increased during the course of the multi-episodic eruption. Magmatic Plinian events alternated with phreatoplinian eruptions and phreatomagmatic explosions generating surges that typically preceded breaks in activity. While single eruptive episodes lasted for few hours, the entire eruption probable lasted weeks to months. This is indicated by changes in atmospheric conditions and ash-layer surfaces that had become modified during the breaks in activity. The Masaya Triple Layer has allowed to reconstruct in detail how a basaltic Plinian eruption develops in terms of duration, episodicity, and variable access of external water to the conduit, with implications for volcanic hazard assessment

The worldwide marine radiocarbon reservoir effect: definitions, mechanisms, and prospects

When a carbon reservoir has a lower radiocarbon content than the atmosphere, this is referred to as a reservoir effect. This is expressed as an offset between the radiocarbon ages of samples from the two reservoirs at a single point in time. The marine reservoir effect (MRE) has been a major concern in the radiocarbon community, as it introduces an additional source of error that is often difficult to accurately quantify. For this reason, researchers are often reluctant to date marine material where they have another option. The influence of this phenomenon makes the study of the MRE important for a broad range of applications. The advent of Accelerator Mass Spectrometry (AMS) has reduced sample size requirements and increased measurement precision, in turn increasing the number of studies seeking to measure marine samples. These studies rely on overcoming the influence of the MRE on marine radiocarbon dates through the worldwide quantification of the local parameter ΔR, that is, the local variation from the global average MRE. Furthermore, the strong dependence on ocean dynamics makes the MRE a useful indicator for changes in oceanic circulation, carbon exchange between reservoirs, and the fate of atmospheric CO2, all of which impact Earth's climate. This article explores data from the Marine Reservoir Database and reviews the place of natural radiocarbon in oceanic records, focusing on key questions (e.g., changes in ocean dynamics) that have been answered by MRE studies and on their application to different subjects

A comparison of biomarker records of northeast African vegetation from lacustrine and marine sediments (ca. 3.40 Ma)

Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Organic Geochemistry 38 (2007): 1607-1624, doi:10.1016/j.orggeochem.2007.06.008.Integrated terrestrial and marine records of northeast African vegetation are needed to provide long, high resolution records of environmental variability with established links to specific terrestrial environments. In this study, we compare records of terrestrial vegetation preserved in marine sediments in the Gulf of Aden (DSDP Site 231) and an outcrop of lacustrine sediments in the Turkana Basin, Kenya, part of the East African Rift System. We analyzed higher plant biomarkers in sediments from both deposits of known equivalent age, corresponding to a ca. 50 – 100 ka humid interval prior to the β-Tulu Bor eruption ca. 3.40 Ma, when the Lokochot Lake occupied part of the Turkana Basin. Molecular abundance distributions indicate that long chain n-alkanoic acids in marine sediments are the most reliable proxy for terrestrial vegetation (Carbon Preference Index, CPI, = 4.5), with more cautious interpretation needed for n-alkanes and lacustrine archives. Marine sediments record carbon isotopic variability in terrestrial biomarkers of 2 – 3‰, roughly equivalent to 20% variability in the C3/C4 vegetation contribution. The proportion of C4 vegetation apparently increased at times of low terrigenous dust input. Terrestrial sediments reveal much larger (2 – 10‰) shifts in n-alkanoic acid δ13C values. However, molecular abundance and isotopic composition suggest that microbial sources may also contribute fatty acids, contaminating the lacustrine sedimentary record of terrestrial vegetation.Funding was provided by the U.S. National Science Foundation HOMINID Grant 0218511