Transform-margin development around the Arctic Ocean is a predictable geometric outcome of multi-stage spreading of a small, confined ocean under radically changing plate vectors. Recognition of several transform-margin stages in the development of the Arctic Ocean enables predictions to be made regarding tectonic styles and petroleum systems. The De Geer margin, connecting the Eurasia Basin (the younger Arctic Ocean) and the NE Atlantic during the Cenozoic, is the best known example. It is dextral, multi-component, features transtension and transpression, is implicated in microcontinent release, and thus bears close comparison with the Equatorial Shear Zone. In the older Arctic Ocean, the Amerasia Basin, Early Cretaceous counterclockwise rotation around a pole in the Canadian Mackenzie Delta was accommodated by a terminal transform. We argue on geometric grounds that this dislocation may have occurred at the Canada Basin margin rather than along the more distal Lomonosov Ridge, and review evidence that elements of the old transform margin were detached by the Makarov–Podvodnikov opening and accommodated within the Alpha–Mendeleev Ridge. More controversial is the proposal of transform along the Laptev–East Siberian margin. We regard an element of transform motion as the best solution to accommodating Eurasia and Makarov–Podvodnikov Basin opening, and have incorporated it into a three-stage plate kinematic model for Cretaceous–Cenozoic Arctic Ocean opening, involving the Canada Basin rotational opening at 125–80 Ma, the Makarov–Povodnikov Basin opening at 80–60 Ma normal to the previous motion and a Eurasia Basin stage from 55 Ma to present. We suggest that all three opening phases were accompanied by transform motion, with the right-lateral sense being dominant. The limited data along the Laptev–East Siberian margin are consistent with transform-margin geometry and kinematic indicators, and these ideas will be tested as more data become available over less explored parts of the Arctic, such as the Laptev–East Siberia–Chukchi margin.

It is only in the last 100 years or so that most of Britain has been covered by accurate, published, topographic and geological maps. Although travellers’ guides were available from the late seventeenth century, they lacked adequate maps. Whilst fairly accurate maps of the major roads were published in the early seventeenth century as strip maps, topographic maps were not generally available until the nineteenth century. Cartographers, usually when preparing county maps, struggled with the representation of Britain’s varied topography. In the nineteenth century, medium-scale (1-inch-to-the-mile) topographic maps initially developed through the agency of the prizes offered by the Royal Society of Arts but primarily due to the Ordnance Survey. Geological maps benefitted from improved base maps – those of John Cary and the Ordnance Survey. This paper especially explores and illustrates the development of maps and the role they played in the depiction and understanding of landscape and promotion of the major early geotourism region of the Peak District from 1780 to 1930.

Sealed, submerged palaeoenvironmental deposits date the time range for lithic technologies and enable inferences about cultural change – potentially more accurately than radiometric methods. Sea-level rises triggered by global warming reduce available land, and change the availability of flora, fauna, geological resources, rivers and wetlands. Australian archaeological studies on human adaptation to climate change focus mainly on terrestrial sites, coastal intensification and the few archaeological sites that were not inundated.The South West Arm project at Port Hacking, south of Sydney, looks at the potential for rock shelters to survive inundation and expand the sites available for studying human adaption to climate change.Site prediction was based on recorded terrestrial rock-shelter landforms at South West Arm. Underwater surveys were conducted by divers who located, photographed and mapped similar formations. No excavation was conducted.The pre-disturbance survey examined approximately 1800 m of seabed, between water depths of 0 and 9 m, primarily along the eastern shoreline of South West Arm where the seabed emulates the steep slope, with sandstone rock outcrops that form terraces and rock overhangs above water.Twelve submerged rock overhangs were recorded and confirmed the potential for rock-shelter sites to survive the process of inundation.

Thermal observations of volcanic activity when the volcano is partially covered by clouds or observed under a wide-scan angle are often removed from further analyses. In the event of a volcanic crisis, such a reduced set of data is not adequate. Even when the observation conditions are favourable, the full observation set is still required to provide decision-makers with quality information about the data. Automatic quality estimation and outlier detection was not estimated in the past. We propose to analytically define the uncertainty for individual observations based on the measurement circumstances. To additionally reduce the temporal noise of the radiant power (RP) time series we apply a Kalman Filter (KF). The KF is able to recursively analyse an unevenly sampled time series. Based on some proposed rules, it can also detect outliers. We apply the proposed methodology to the 2008–09 Etna eruption monitored by MODIS (Moderate Resolution Imaging Spectroradiometer). The analysis of the results shows that the topography has a greater influence on RP than previously considered.

VolcFlow is a finite-difference Eulerian code based on the depth-averaged approach and developed for the simulation of isothermal geophysical flows. Its capability for reproducing lava flows is tested here for the first time. The field example chosen is the 2010 lava flow of Tungurahua volcano (Ecuador), the emplacement of which is tracked by projecting thermal images onto a georeferenced digital topography. Results show that, at least for this case study, the isothermal approach of VolcFlow is able to simulate the velocity of the lava through time, as well as the extent of the solidified lava. However, the good fit between the modelled and the natural flow may be explained by the short emplacement time (c. 20 h) of a thick lava (c. 5 m), which could limit the influence of cooling on the flow dynamics, thus favouring the use of an isothermal rheology.

GPUSPH is a fully three-dimensional model for the simulation of the thermal and rheological evolution of lava flows that relies on the Smoothed Particle Hydrodynamics (SPH) numerical method. Thanks to the Lagrangian, meshless nature of SPH, the model incorporates a more complete physical description of the emplacement process and rheology of lava that considers the free surface, the irregular boundaries represented by the topography, the solidification fronts and the non-Newtonian rheology with temperature-dependent parameters. GPUSPH follows the very general Herschel–Bulkley rheological model, which encompasses Newtonian, power-law and Bingham flow behaviours, with both constant and temperature-dependent parameters, and can thus be used to explore in detail the impact of rheology on the behaviour of lava flows and on their emplacement. To illustrate this possibility, we present some preliminary applications of the model for studying the rheology of lava flows with different constitutive relationships and thermal regimes using the real topography of the Mt Etna volcano.

A new shallow-depth approximation model for lava flow advance and cooling on a quantized topography is presented in this paper. To apply the model, lava rheology is described using a non-isothermal three-dimensional viscoplastic fluid in which the rheological properties are assumed to be temperature dependent. Asymptotic analysis allows a three-dimensional flow scenario to be reduced to a two-dimensional problem using depth-averaged equations. These equations are numerically approximated by an autoadaptive finite element method, based on the Rheolef C++ library, which allows economy of computational time. Here, the proposed approach is first evaluated by comparing numerical output with non-isothermal experimental results for a flow of silicon oil. Finally, the December 2010 eruption of Piton de la Fournaise (La Réunion Island) is numerically reproduced and compared with available data.

The surficial geology of the Baraboo area is very important because it includes the transition from a glaciated region to the Driftless Area. The eastern portion of this area was glaciated as part of the Green Bay lobe of the ice sheet in this area. The terminal moraine is present and is characterized by sandy till. No valid information that substantiates glacial activity exists west of the city of Baraboo. The Driftless Area includes a site of the earliest Wisconsin habitation.

South-central Utah’s prominent sandstones and deeply dissected landscapes are the focus of this four-day trip, which begins and ends in Grand Junction, Colorado. Studies of the apatite grains in sandstones adjacent to igneous intrusions are revealing new information on the timing and rate of Cenozoic erosion. Iron-oxide cemented concretions in other rocks record how reduced-iron carbonates and subsurface microbes interacted when near-surface, oxygenated waters started to flush the reducing, CO2-rich waters from Colorado Plateau aquifers. New geochronologic techniques that are being applied to the plateau rocks have the potential to expand our knowledge of how diagenetic episodes relate to the evolving topography of this classic geologic setting.

The San Luis Basin encompasses the largest structural and hydrologic basin of the Rio Grande rift. On this field trip, we will examine the timing of transition of the San Luis Basin from hydrologically closed, aggrading subbasins to a continuous fluvial system that eroded the basin, formed the Rio Grande gorge, and ultimately, integrated the Rio Grande from Colorado to the Gulf of Mexico. Waning Pleistocene neotectonic activity and onset of major glacial episodes, in particular Marine Isotope Stages 11–2 (~420–14 ka), induced basin fill, spillover, and erosion of the southern San Luis Basin. The combined use of new geologic mapping, fluvial geomorphology, reinterpreted surficial geology of the Taos Plateau, pedogenic relative dating studies, 3He surface exposure dating of basalts, and U-series dating of pedogenic carbonate supports a sequence of events wherein pluvial Lake Alamosa in the northern San Luis Basin overflowed, and began to drain to the south across the closed Sunshine Valley–Costilla Plain region ≤400 ka. By ~200 ka, erosion had cut through topographic highs at Ute Mountain and the Red River fault zone, and began deep-canyon incision across the southern San Luis Basin. Previous studies indicate that prior to 200 ka, the present Rio Grande terminated into a large bolson complex in the vicinity of El Paso, Texas, and systematic, headward erosional processes had subtly integrated discontinuously connected basins along the eastern flank of the Rio Grande rift and southern Rocky Mountains. We propose that the integration of the entire San Luis Basin into the Rio Grande drainage system (~400–200 ka) was the critical event in the formation of the modern Rio Grande, integrating hinterland basins of the Rio Grande rift from El Paso, Texas, north to the San Luis Basin with the Gulf of Mexico. This event dramatically affected basins southeast of El Paso, Texas, across the Chisos Mountains and southeastern Basin and Range province, including the Rio Conchos watershed and much of the Chihuahuan Desert, inducing broad regional landscape incision and exhumation.

The Shatsky Rise is one of the largest oceanic plateaus, a class of volcanic features whose formation is poorly understood. It is also a plateau that was formed near spreading ridges, but the connection between the two features is unclear. The geologic structure of the Shatsky Rise can help us understand its formation. Deeply penetrating two-dimensional (2-D) multichannel seismic (MCS) reflection profiles were acquired over the southern half of the Shatsky Rise, and these data allow us to image its upper crustal structure with unprecedented detail. Synthetic seismograms constructed from core and log data from scientific drilling sites crossed by the MCS lines establish the seismic response to the geology. High-amplitude basement reflections result from the transition between sediment and underlying igneous rock. Intrabasement reflections are caused by alternations of lava flow packages with differing properties and by thick interflow sediment layers. MCS profiles show that two of the volcanic massifs within the Shatsky Rise are immense central volcanoes. The Tamu Massif, the largest (~450 km × 650 km) and oldest (ca. 145 Ma) volcano, is a single central volcano with a rounded shape and shallow flank slopes (<0.5°–1.5°), characterized by lava flows emanating from the volcano center and extending hundreds of kilometers down smooth, shallow flanks to the surrounding seafloor. The Ori Massif is a large volcano that is similar to, but smaller than, the Tamu Massif. The morphology of the massifs implies formation by extensive and far-ranging lava flows emplaced at small slope angles. The relatively smooth flanks of the massifs imply that the volcanoes were not greatly affected by rifting due to spreading ridge tectonics. Deep intrabasement reflectors parallel to the upper basement surface imply long-term isostasy with the balanced addition of material to the surface and subsurface. No evidence of subaerial erosion is found at the summits of the massifs, suggesting that they were never highly emergent.

The evolution of surface topography in an orogen provides information about the dynamics of the deep lithosphere. Within the high-elevation Altiplano-Puna Plateau of the central Andes, there are several local basins (~100 km wide) that sit >500 m lower than the surrounding plateau. These areas correspond to positive isostatic gravity anomalies, indicating high density in the lithosphere. There are also examples of former basins that are now at high elevation (e.g., the Miocene Arizaro Basin), suggesting that the basins are transient features that may be related to convective removal of lithosphere. Two-dimensional numerical models are used to investigate the topographic expression associated with removal of a high-density lithosphere root. A key result is that the presence of thick orogenic crust, as found in the Altiplano-Puna Plateau, can greatly affect the surface deflection above the detaching root. Three types of deflection are observed: (1) >500 m subsidence, followed by uplift, (2) little subsidence, and (3) uplift followed by collapse. The main control on the deflection is the viscous coupling between the root and surface, which decreases with increased root depth or weaker crust. If the crust is weak, the dense root induces crustal flow, resulting in thickened crust and either limited subsidence or uplift above the dripping lithosphere. Significant subsidence only occurs if the deep crust is relatively strong and the density anomaly is located within the crust. To produce surface deflection over a width of ~100 km, the near-surface rocks must be relatively weak.

Intraplate earthquakes, like the recent moment magnitude, Mw 5.8 Mineral, Virginia (USA), earthquake of 23 August 2011, are sobering reminders of how little we know about the lithosphere and active tectonics of plate interiors, including passive continental margins. Unlike plate boundaries, plate interiors typically lack clear geologic evidence of the tectonic stresses that lead to earthquakes, the deformation of rocks, and the building of topography. Inspired by the Mineral earthquake, preliminary geophysical and geomorphic work in the Central Virginia seismic zone, centered in Louisa County, resolves apparent surface deformation expressed in geomorphic markers and river channel patterns. This deformation is consistent with the location and sense of slip of the reverse fault that ruptured in the Mineral earthquake. Surface deformation is recorded by the modern and ancient longitudinal profile of the South Anna River that flows above the epicenter of the earthquake and orthogonal to the structural grain of the Appalachian Piedmont. Sinuosity of the South Anna River channel is greatest in the uplifted hanging wall of the fault that ruptured in the Mineral earthquake. More dramatically, preliminary correlations of terrace deposits of the paleo–South Anna River suggest that they are several meters higher above the modern channel in the hanging wall with respect to the footwall of the Mineral fault rupture plane. The implication is that persistent faulting in the vicinity of the Mineral earthquake, over many millennia, has resulted in several meters of cumulative rock and surface uplift of the eastern hanging-wall block with respect to its western footwall. This is a rare example of crustal and surface deformation directly linked to observed seismicity in eastern North America, where earthquakes have long been observed to cluster spatially. If confirmed by ongoing mapping, these results serve as a surface deformation field constraint for geodynamic models of intraplate earthquake generation and associated hazards in a passive margin setting.

This one-day field trip highlights research into the late Cenozoic evolution of topography in the Appalachian Mountains through geomorphic observations in the Cullasaja River basin, located in Macon County, North Carolina. Herein we present observations, data, and modeling results that challenge the paradigm of the Appalachians as a dead and slowly decaying orogen. Previous studies on the Cenozoic evolution of topography in the Appalachians are reviewed, showing that the post-orogenic history of eastern North America is best described by spatial and temporal changes in topographic relief, erosion rate, and sediment flux. When these data sets are placed in the context of other geologic and geophysical studies, they indicate that the Appalachians are a dynamic mountain range. We review previous studies in the Cullasaja basin that document and characterize the magnitude of base-level fall, relief production, and ensuing landscape response to such changes. These studies show that topographic relief within the basin was relatively subdued in the Miocene and subsequently has been rejuvenated ~160%, transforming the landscape into the rugged mountains we recognize today. We highlight hillslope and fluvial geomorphic observations that show landscape disequilibrium associated with ongoing adjustment to ~500 m of late Cenozoic base-level fall. Potential mechanisms for topographic rejuvenation of the Appalachians, such as climate change and epeirogenic uplift, are discussed using available field observations.

In 2014, the geomorphology community marked the 125th birthday of one of its most influential papers, ‘The Rivers and Valleys of Pennsylvania’ by William Morris Davis. Inspired by Davis’s work, the Appalachian landscape rapidly became fertile ground for the development and testing of several grand landscape evolution paradigms, culminating with John Hack’s dynamic equilibrium in 1960. As part of the 2015 GSA Annual Meeting, the Geomorphology, Active Tectonics, and Landscape Evolution field trip offers an excellent venue for exploring Appalachian geomorphology through the lens of the Appalachian landscape, leveraging exciting research by a new generation of process-oriented geomorphologists and geologic field mapping. Important geomorphologic scholarship has recently used the Appalachian landscape as the testing ground for ideas on long- and short-term erosion, dynamic topography, glacial-isostatic adjustments, active tectonics in an intraplate setting, river incision, periglacial processes, and soil-saprolite formation.This field trip explores a geologic and geomorphic transect of the mid-Atlantic margin, starting in the Blue Ridge of Virginia and proceeding to the east across the Piedmont to the Coastal Plain. The emphasis here will not only be on the geomorphology, but also the underlying geology that establishes the template and foundation upon which surface processes have etched out the familiar Appalachian landscape. The first day focuses on new and published work that highlights Cenozoic sedimentary deposits, soils, paleosols, and geomorphic markers (terraces and knickpoints) that are being used to reconstruct a late Cenozoic history of erosion, deposition, climate change, and active tectonics. The second day is similarly devoted to new and published work documenting the fluvial geomorphic response to active tectonics in the Central Virginia seismic zone (CVSZ), site of the 2011 M 5.8 Mineral earthquake and the integrated record of Appalachian erosion preserved on the Coastal Plain. The trip concludes on Day 3, joining the Kirk Bryan Field Trip at Great Falls, Virginia/Maryland, to explore and discuss the dramatic processes of base-level fall, fluvial incision, and knickpoint retreat.

In the easternmost Himalaya and southeastern Tibet, the Namche Barwa–Gyala Peri massif and adjacent Lhasa block host some of the Earth’s most active geologic processes and extreme topography. Synthesis of U-Th/He and Ar-Ar thermochronology, anatectic history, seismicity, and structural geology shows the important role that surface processes have played in this region in both local and orogen-scale crustal dynamics. Basement rocks of the massif underwent an episode of metamorphism, partial melting, and focused deformation that began ca. 10 Ma and likely remains active due to thermally mediated feedbacks between these processes and erosion. Strong differential rock uplift at Namche Barwa established the immense Namche Barwa knickzone on the Yarlung Tsangpo River, which has been stabilized through coupling between erosion driven by high stream power and localized deformation. This knickzone has maintained a high secondary base level of ~3000 m for the upper Yarlung Tsangpo watershed and so has shielded a large region of southeastern Tibet from excavation by the river, which in turn could alter the morphology and so the dynamics of the eastern Himalayan orogenic wedge. The landscape evolution of the southeast Lhasa block involved slow regional unroofing or incision in the Neogene, a significant pulse of ~5 km of rapid exhumation from ca. 10 to 5 Ma, and since then a great reduction in exhumation started once the Namche Barwa knickzone on the Yarlung Tsangpo was established. The low-relief high-elevation surface in the area is a relatively young feature, developed after the rapid 10–5 Ma exhumation pulse.

Spatiotemporal patterns of Cenozoic deformation along the margins of the Tibetan Plateau can provide key evidence with which to investigate the mechanisms of continental deformation and plateau growth as well as their impact on regional climate. Along the northeastern margin of the Tibetan Plateau, Cenozoic deformation and regional aridification have been attributed to the upward and outward growth of the plateau. Analysis of stratigraphic and stable isotopic data shows that, in early to middle Miocene time, intracontinental mountain ranges subdivided a broad foreland basin, which developed on the northern margin of the Tibetan Plateau shortly after collision between India and Eurasia, into smaller intramontane basins. Stratigraphic and stable isotope data collected from a number of subbasins along the northeastern Tibetan Plateau, spanning as much as 30 m.y. in age and ranging to 3 km in thickness, reveal a pattern of deformation and basin isolation that began ca. 22 Ma with the initial unroofing of the eastern Laji Shan near the town of Minhe and partially separated the Xining basin from the Hualong, Linxia, and Xunhua basins to the south. Westward paleoflow indicators on the eastern margin of the Guide basin indicate that the Zamazari Shan had attained topographic relief by ca. 20 Ma and separated the Guide basin from the Jian Zha, Hualong, and Xunhua basins to the east. Deformation of the Laji Shan–Jishi Shan progressed to the south, deforming the Jishi Shan ca. 13 Ma and separating the Linxia Basin from the Hualong and Xunhua basins to the west. Final separation between the Jian Zha and Xining basins occurred at 10–8 Ma with the growth of the western Laji Shan and Riyue Shan. Unique stable isotope records reflect the different hydrologic and tectonic settings of each basin and highlight the importance of local climate conditions in each basin. However, ca. 14 Ma all basins underwent a synchronous change in climate toward more arid conditions, as indicated by a gradual to abrupt positive shift in δ18O values. This climate event corresponds with aridification events to the west near the Qaidam basin and may be related to the reorganization of vapor transport pathways around a growing eastern Tibetan Plateau.

This study investigates the impacts of extratropical cyclones on Lake Michigan dune complexes by integrating field measurements and meteorological data from sites along the southeastern shore. Surface changes and wind velocities were monitored at Hoffmaster State Park, Saugatuck Harbor Natural Area, and Mount Baldy at Indiana Dunes National Lakeshore from October to April in 2010–2011 and 2011–2012. Over 70% of the events with wind speeds at least two standard deviations above the mean were associated with extratropical cyclones. The wind directions depended on the cyclone path, with westerly or southerly components most common. Local conditions moderated the effects of storm winds on surface change. The greatest surface changes measured in a trough blowout at Saugatuck Harbor Natural Area were associated with regional winds with a component blowing up the lee slope that produced bifurcated windflow within the trough. While the orientation of a given dune strongly influences the amount of surface change, it does not always follow a simple pattern deduced from dune geometry. Surface changes at Hoffmaster State Park and Saugatuck Harbor Natural Area during a normal winter (2010–2011) and an unusually warm winter (2011–2012) suggest that colder weather conditions inhibited net transfer of sand from the beach but had less impact away from the shore. Moisture also inhibited sand transport, but strong storm winds moved wet sand, sometimes over long distances at Indiana Dunes National Lakeshore. Overall our results show that winds associated with extratropical cyclones play a vital role in the development of Lake Michigan dune complexes.