Areal Patterns Research Articles

The influence of through-thickness reinforcement geometry and pattern on delamination of fiber-reinforced composites: Part II – Modeling

This article reports modeling techniques and results based on experimental Mode I characterization of a layered woven GFRP material with tufting reinforcement. Standard tuft and loop-less geometries are investigated on three different areal patterns to evaluate their effects on fracture resistance. The experiments reveal that tow/ply and tuft bridging phenomena are present during delamination. The numerical modeling comprises cohesive elements for tow/ply bridging and 1D connector elements for discrete tufts. The traction separation relations for the cohesive model are acquired using an inverse scheme based on strain measurements and the force-separation relations of tuft’s failure mechanisms from uniaxial pulling tests on a reference tufting pattern. Results show that tuft’s failure mechanism is strongly affected by tufting pattern and geometry while tow/ply bridging contributes 20–30% of the overall fracture energy. The energy absorbed by pull-out of loop-less tufts is approximately twice the fracture energy of standard ones with pull-out triggering much more extensive tow/ply bridging phenomena.

Cultural patterns within and outside of the post-contact Great Plains as revealed by parfleche characteristics: Implications for areal arrangements in artifactual data

For some time it has been recognized that areal arrangements in ethnographic data might help archaeologists understand equivalent arrangements in artifactual data, especially in anthropologically relevant terms. Equally, ethnographic data have shown that material-culture patterns do not necessarily conveniently map discrete “peoples” or ethnolinguistic communities. However, the question still persists as to whether areal patterns in artifactual data represent anthropologically important information, and if so, how. Ethnographically, studies of these issues have tended to adopt two approaches. Some studies have examined areal patterning across broad geographic areas in terms of presences and absences of particular artifacts or suites of artifacts. Alternatively, studies have looked at variation in the stylistic traits of particular artifacts, but over a relatively more discrete geographic range, typically a sub-region defined on the basis of other cultural and/or ecological distinctions. Here, in this study a different approach is taken, whereupon variations in the inter-tribe attributes of a singular artifact class (post-contact-era “parfleches” or decorated rawhide bags) are examined over a wide geographic area (western North America). Multivariate statistical analyses demonstrate that among-tribe variation in parfleche characteristics most strongly conforms to three geographic stylistic regions and, moreover, that these three stylistic regions disregard linguistic affiliations and “culture area” designations. These trait-level patterns conform to documented trade patterns across the study area, explaining why these areal patterns disregard distinctions made on other criteria. Ultimately, the study demonstrates ethnographically the value of contrasting areal patterns based on discrete artifactual distinctions (i.e., presence and absence of particular artifacts) versus broader-scale, but trait-level, patterns in artifacts common across these different areas.

Profiling Indo-Aryan in the Hindukush-Karakoram: A preliminary study of micro-typological patterns

Abstract The study is a typological profile of 31 Indo-Aryan (IA) languages in the Hindukush-Karakoram-Western Himalayan region (covering NE Afghanistan, N Pakistan, and parts of Kashmir). Native speakers were recruited to provide comparative data. This data, supplemented by reputable descriptions or field notes, was evaluated against a number of WALS- or WALS-like features, enabling a fine-tuned characterization of each language, taking different linguistic domains into account (phonology, morphology, syntax, lexicon). The emerging patterns were compared with global distributions as well as with characteristic IA features and well-known areal patterns. Some features, mainly syntactic, turned out to be shared with IA in general, whereas others do have scattered reflexes in IA outside of the region but are especially prevalent in the region: large consonant inventories, tripartite pronominal case alignment, a high frequency of left-branching constructions, and multi-degree deictic systems. Yet other features display a high degree of diversity, often bundling subareally. Finally, there was a significant clustering of features that are not characterizing IA in general: tripartite affricate differentiation, retroflexion across several subsets, aspiration contrasts involving voiceless consonants only, tonal contrasts and 20-based numerals. This clustering forms a “hard core” at the centre of the region, gradually fading out toward its peripheries.

Gravity currents down canyons: effects of rotation

The flow of dense water in a V-shaped laboratory-scale canyon is investigated by using a non-hydrostatic numerical ocean model with focus on the effects of rotation. By using a high-resolution model, a more detailed analysis of plumes investigated in the laboratory (Deep-Sea Res I 55:1021–1034 2008) for laminar flow is facilitated. The inflow rates are also increased to investigate plume structure for higher Reynolds numbers. With rotation, the plumes will lean to the side of the canyon, and there will be cross-canyon geostrophic currents and Ekman transports. In the present study, it is found that the cross-canyon velocities are approximately 5 % of the down-canyon velocities over the main body of the plume for the rotational case. With rotation, the flow of dense water through the body of the plume and into the plume head is reduced. The plume head becomes less developed, and the speed of advance of the head is reduced. Fluid parcels near the top of the plume will to a larger extent be left behind the faster flowing dense core of the plume in a rotating system. Near the top of the plume, the cross-canyon velocities change direction. Inside the plume, the cross-flow is up the side of the canyon, and above the interface to the ambient there is a compensating cross-flow down the side of the canyon. This means that parcels of fluid around the interface become separated. Parcels of fluid around the interface with small down-canyon velocity components and relative large cross-canyon components will follow a long helix-like path down the canyon. It is found that the entrainment coefficients often are larger in the rotational experiments than in corresponding experiments without rotation. The effects of rotation and higher inflow rates on the areal patterns of entrainment velocities are demonstrated. In particular, there are bands of higher entrainment velocities along the lateral edges of the plumes in the rotational cases.

Revealing the natural complexity of topographic change processes through repeat surveys and decision‐tree classification

AbstractTopographic change processes (TCPs) are the mechanisms by which a landscape is interpreted to be experiencing landform deformation, and are defined by the specific actions occurring within a contiguous, localized region that cause sediment to be either deposited or eroded. Past topographic change studies have mostly been focused at the site scale. The goal of this study was to identify and delineate spatially explicit TCP types across the valley width in a 34‐km long cobble‐gravel river at the scale of one‐tenth of the bankfull channel width over a period of seven to nine years. To accomplish this, a new procedure was developed that analyzes spatial patterns of topographic change evident from differencing two raster digital elevation models and accounting for sources of uncertainty, then identifying and classifying those changes using a decision tree framework that invokes the locations of those changes as they relate to the locations of specific geographic characteristics. Once mapped, TCP polygons were analyzed for areal patterns and volumetric rates of change. Results showed that 19 unique TCP types occurred and that they have organized but complex spatial patterns. Within this study segment, overbank storage processes occurred over the most area and displaced the most net volume of sediment, while cohesive bank retreat created the largest net change in topographic elevations. Analyses of the TCPs reveal that the regulated lower Yuba River (LYR) is not experiencing the expected combination of channel incision and floodplain deposition commonly reported below dams. Instead, the LYR is a dynamic valley that is still adjusting valley‐wide to the upstream dam with a diverse suite of processes that cause the channel and floodplains to scour and fill in concert. Copyright © 2015 John Wiley & Sons, Ltd.

Detecting volcanic resurfacing of heavily cratered terrain: Flooding simulations on the Moon using Lunar Orbiter Laser Altimeter (LOLA) data

Early extrusive volcanism from mantle melting marks the transition from primary to secondary crust formation. Detection of secondary crust is often obscured by the high impact flux early in solar system history. To recognize the relationship between heavily cratered terrain and volcanic resurfacing, this study documents how volcanic resurfacing alters the impact cratering record and models the thickness, area, and volume of volcanic flood deposits. Lunar Orbiter Laser Altimeter (LOLA) data are used to analyze three different regions of the lunar highlands: the Hertzsprung basin; a farside heavily cratered region; and the central highlands. Lunar mare emplacement style is assumed to be similar to that of terrestrial flood basalts, involving large volumes of material extruded from dike-fed fissures over relatively short periods of time. Thus, each region was flooded at 0.5km elevation intervals to simulate such volcanic flooding and to assess areal patterns, thickness, volumes, and emplacement history. These simulations show three primary stages of volcanic flooding: (1) Initial flooding is largely confined to individual craters and deposits are thick and localized; (2) basalt flows breach crater rim crests and are emplaced laterally between larger craters as thin widespread deposits; and (3) lateral spreading decreases in response to regional topographic variations and the deposits thicken and bury intermediate-sized and larger craters. Application of these techniques to the South Pole-Aitken basin shows that emplacement of ∼1−2km of cryptomaria can potentially explain the paucity of craters 20–64km in diameter on the floor of the basin relative to the distribution in the surrounding highlands.

Integration of linear and areal hierarchies for continuous multi-scale representation of road networks

Spatial data can be represented at different scales, and this leads to the issue of multi-scale spatial representation. Multi-scale spatial representation has been widely applied to online mapping products (e.g., Google Maps and Yahoo Maps). However, in most current products, multi-scale representation can only be achieved through a series of maps at fixed scales, resulting in a discontinuity (i.e., with jumps) in the transformation between scales and a mismatch between the available scales and users' desired scales. Therefore, it is very desirable to achieve smoothly continuous multi-scale spatial representations. This article describes an integrated approach to build a hierarchical structure of a road network for continuous multi-scale representation purposes, especially continuous selective omission of roads in a network. In this hierarchical structure, the linear and areal hierarchies are constructed, respectively, using two existing approaches for the linear and areal patterns in a road network. Continuous multi-scale representation of a road network can be achieved by searching in these hierarchies. This approach is validated by applying it to two study areas, and the results are evaluated by both quantitative analysis with two measures (i.e., similarity and average connectivity) and visual inspection. Experimental results show that this integrated approach performs better than existing approaches, especially in terms of preservation of connectivity and patterns of a road network. With this approach, efficient and continuous multi-scale selective omission of road networks becomes feasible.

Rate/state Coulomb stress transfer model for the CSEP Japan seismicity forecast

Numerous studies retrospectively found that seismicity rate jumps (drops) by coseismic Coulomb stress increase (decrease). The Collaboratory for the Study of Earthquake Prediction (CSEP) instead provides us an opportunity for prospective testing of the Coulomb hypothesis. Here we adapt our stress transfer model incorporating rate and state dependent friction law to the CSEP Japan seismicity forecast. We demonstrate how to compute the forecast rates of large shocks in 2009 using the large earthquakes during the past 120 years. The time dependent impact of the coseismic stress perturbations explains qualitatively well the occurrence of the recent moderate size shocks. Such ability is partly similar to that of statistical earthquake clustering models. However, our model differs from them as follows: the off-fault aftershock zones can be simulated using finite fault sources; the regional areal patterns of triggered seismicity are modified by the dominant mechanisms of the potential sources; the imparted stresses due to large earthquakes produce stress shadows that lead to a reduction of the forecasted number of earthquakes. Although the model relies on several unknown parameters, it is the first physics based model submitted to the CSEP Japan test center and has the potential to be tuned for short-term earthquake forecasts.

Dual Mechanism of Neuronal Ensemble Inhibition in Primary Auditory Cortex

Inhibition plays an essential role in shaping and refining the brain's representation of sensory stimulus attributes. In primary auditory cortex (A1), so-called "sideband" inhibition helps to sharpen the tuning of local neuronal responses. Several distinct types of anatomical circuitry could underlie sideband inhibition, including direct thalamocortical (TC) afferents, as well as indirect intracortical mechanisms. The goal of the present study was to characterize sideband inhibition in A1 and to determine its mechanism by analyzing laminar profiles of neuronal ensemble activity. Our results indicate that both lemniscal and nonlemniscal TC afferents play a role in inhibitory responses via feedforward inhibition and oscillatory phase reset, respectively. We propose that the dynamic modulation of excitability in A1 due to the phase reset of ongoing oscillations may alter the tuning of local neuronal ensembles and can be regarded as a flexible overlay on the more obligatory system of lemniscal feedforward type responses.

Calibration of uncertain flood inundation models using remotely sensed water levels

Summary A traditional method of validating the performance of a flood model when remotely sensed data of the flood extent are available is to compare the predicted flood extent to that observed. The performance measure employed often uses areal pattern-matching to assess the degree to which the two extents overlap. Recently, remote sensing of flood extents using synthetic aperture radar (SAR) and airborne scanning laser altimetry (LiDAR) has made more straightforward the synoptic measurement of water surface elevations along flood boundaries (waterlines), and this has emphasised the possibility of using alternative performance measures based on height. This paper considers the advantages that can accrue from using a performance measure based on waterline elevations rather than one based on areal patterns of wet and dry pixels. The two measures were compared for their ability to estimate flood inundation uncertainty maps from a set of LISFLOOD-FP model runs carried out to span the acceptable model parameter range. A 1-in-5-year flood on the Thames in 1992, observed in an ERS-1 SAR image, was used as a test event. Waterlines were delineated in fused SAR and LiDAR data using an active contour model (snake). The performance measure based on height differences of corresponding points along the observed and modelled waterlines was found to be significantly more sensitive to the channel friction parameter than the measure based on areal patterns of flood extent. A result of this was that there was less uncertainty in the final flood hazard map. The height-based measure was found to be more sensitive when increased heighting accuracy was achieved by requiring that observed waterline heights varied slowly along the reach. The technique was shown to allow the decomposition of the reach into sections, with different effective channel friction parameters used in different sections. However, an evaluation of the modelled inundation uncertainty using the calibration event showed significant differences between the uncertainty map and the observed flood extent, especially for the height-based measure. This was probably due to the conceptually simple flood inundation model and the coarse application resolution employed in this case. The increased sensitivity of the height-based measure may lead to an increased onus being placed on the model developer in the production of a valid model.

Methodology and the empirical base of typology

A significant part of the debate over the practice of “good” linguistic typology is concerned with the issue of methodology that can produce generalizations at a satisfactory depth based on a satisfactory sample size. As the articles in this collection themselves attest, there is no single goal for typology: the inventory of possible human language structures, variation within a phenomenon, the diffusion of particular phenomena, areal patterns, as well as the stability of linguistic phenomena over time are just a sampling of the concerns which typologists have had. Even given such diverse goals – where methodological differences might be take for granted as necessary – the debate over typological methodology persists.

Toward a geotypology of EAT-expressions in languages of Asia: Visualizing areal patterns through WALS

Many of the languages of Asia have families of expressions in which a verb meaning EAT exhibits Janus-faced behavior. In some cases the subject of EAT bears the semantic role of an agent while in others it bears the role of a theme, patient, or experienccr. A central concern of this paper is to characterize the geographic distribution in Asia of the semantic extensions of the experientially basic verb EAT in selected languages. We graph the areal distribution of representative EAT expressions as sets of data points on WALS maps and show that while some metaphoric extensions of usage of the verb EAT are probably found in every language, other particular types of extensions are found only in a specific area whose languages share a number of typological characteristics as shown by Masica (1976) in his seminal work on the SOV linguistic area of South, Central, and Northeast Asia. While language contact certainly has played and continues to play a significant role, we propose the independent operation of a radial network of semantic extensions as a possible complementary factor in the proliferation and convergence of EAT-expressions.

Shallow soil CO2 flow along the San Andreas and Calaveras Faults, California

We evaluate a comprehensive soil CO2 survey along the San Andreas fault (SAF) in Parkfield, and the Calaveras fault (CF) in Hollister, California, in the context of spatial and temporal variability, origin, and transport of CO2 in fractured terrain. CO2 efflux was measured within grids with portable instrumentation and continuously with meteorological parameters at a fixed station, in both faulted and unfaulted areas. Spatial and temporal variability of surface CO2 effluxes was observed to be higher at faulted SAF and CF sites, relative to comparable background areas. However, δ13C (−23.3 to −16.4‰) and Δ14C (75.5 to 94.4‰) values of soil CO2 in both faulted and unfaulted areas are indicative of biogenic CO2, even though CO2 effluxes in faulted areas reached values as high as 428 g m−2 d−1. Profiles of soil CO2 concentration as a function of depth were measured at multiple sites within SAF and CF grids and repeatedly at two locations at the SAF grid. Many of these profiles suggest a surprisingly high component of advective CO2 flow. Spectral and correlation analysis of SAF CO2 efflux and meteorological parameter time series indicates that effects of wind speed variations on atmospheric air flow though fractures modulate surface efflux of biogenic CO2. The resulting areal patterns in CO2 effluxes could be erroneously attributed to a deep gas source in the absence of isotopic data, a problem that must be addressed in fault zone soil gas studies.

Interdialect contact of Czech (and Slovak) Romani varieties

Diaspora and coexistence of various dialect layers within an area are general features of the Romani dialect situation. Focusing on aspects of interdialect contact, the paper describes the dialect situation of Romani in Czechia and Slovakia. A basic survey is presented of historical, demographic, sociocultural, and linguistic data about different subethnic Rom groups (the Central Roms, the Vlax Roms, and the Sinti) in the two countries. After an analysis of the role of subethnic, kin, and status particularism for linguistic contact, the determinants for various contact strategies (accommodation, bidialectism, common contact language) are identified. The difference between the basically areal patterns of Slovak Central Romani and the prevalently transplanted character of Czech Romani dialects is highlighted, and mixed varieties are briefly discussed. Finally, two types of contact between subethnic dialects with differing consequences for linguistic interference are distinguished.

REGIONAL PATTERNS OF DECOMPOSITION AND PRIMARY PRODUCTION RATES IN THE U.S. GREAT PLAINS*

Warmer regions generally exhibit greater rates of soil respiration and organic matter decomposition than colder regions. In the Great Plains of the United States, soil organic matter declines from the northern part of the region to the south, suggesting greater decomposition rates in areas with warmer temperatures. Our study used a regional data set of aboveground net primary production, soil organic carbon, soil texture, and climate to evaluate the environmental controls over areal patterns in decomposition rates, (k; expressed as grams per year per gram of initial mass), throughout the U.S. Great Plains. We conducted multiple regression analyses of steady-state k with respect to mean annual temperature, mean annual precipitation, and percentage soil clay content to examine both the combined and individual effects of these independent variables on regional decomposition rates. Our results indicated that precipitation contributes more than either temperature or soil texture to areal patterns of decomposition rates in the U.S. Great Plains, explaining >30% of the areal variability in k. Decomposition rates increased with increasing precipitation and with decreasing soil clay content. Temperature explained <8% of the regional variability in k. Ancillary analyses that related temperature and aboveground net primary production in the region indicated that plant productivity declines with increasing temperatures. This suggests that the reduction in soil organic matter to the south in the U.S. Great Plains may be due to reduced plant inputs rather than to increases in decomposition rates. The response of decomposition to temperature is probably constrained by moisture in this water-limited region. Therefore, changes in decomposition rates resulting from temperature dynamics are likely to be minimal unless they are accompanied by sufficient changes in precipitation.

Neurofilament protein: a selective marker for the architectonic parcellation of the visual cortex in adult cat brain.

In this immunocytochemical study, we examined the expression profile of neurofilament protein in the cat visual system. We have used SMI-32, a monoclonal antibody that recognizes a nonphosphorylated epitope on the medium- and high-molecular-weight subunits of neurofilament proteins. This antibody labels primarily the cell body and dendrites of pyramidal neurons in cortical layers III, V, and VI. Neurofilament protein-immunoreactive neurons were prominent in 20 visual cortical areas (areas 17, 18, 19, 20a, 20b, 21a, 21b, and 7; posteromedial lateral, posterolateral lateral, anteromedial lateral, anterolateral lateral, dorsal lateral, ventral lateral, and posterior suprasylvian areas; anterior ectosylvian, the splenial, the cingulate, and insular visual areas; and the anterolateral gyrus area). In addition, we have also found strong immunopositive cells in the A laminae of the dorsal part of the lateral geniculate nucleus (dLGN) and in the medial interlaminar nucleus, but no immunoreactive cells were present in the parvocellular C (1-3) laminae of the dLGN, in the ventral part of the LGN and in the perigeniculate nucleus. This SMI-32 antibody against neurofilament protein revealed a characteristic pattern of immunostaining in each visual area. The size, shape, intensity, and density of neurofilament protein-immunoreactive neurons and their dendritic arborization differed substantially across all visual areas. Moreover, it was also obvious that several visual areas showed differences in laminar distribution and that such profiles may be used to delineate various cortical areas. Therefore, the expression of neurofilament protein can be used as a specific marker to define areal patterns and topographic boundaries in the cat visual system.

Graded and Areal Expression Patterns of Regulatory Genes and Cadherins in Embryonic Neocortex Independent of Thalamocortical Input

The differentiation of areas of the mammalian neocortex has been hypothesized to be controlled by intrinsic genetic programs and extrinsic influences such as those mediated by thalamocortical afferents (TCAs). To address the interplay between these intrinsic and extrinsic mechanisms in the process of arealization, we have analyzed the requirement of TCAs in establishing or maintaining graded or areal patterns of gene expression in the developing mouse neocortex. We describe the differential expression of Lhx2, SCIP, and Emx1, representatives of three different classes of transcription factors, and the type II classical cadherins Cad6, Cad8, and Cad11, which are expressed in graded or areal patterns, as well as layer-specific patterns, in the cortical plate. The differential expression of Lhx2, SCIP, Emx1, and Cad8 in the cortical plate is not evident until after TCAs reach the cortex, whereas Cad6 and Cad11 show subtle graded patterns of expression before the arrival of TCAs, which later become stronger. We find that these genes exhibit normal-appearing graded or areal expression patterns in Mash-1 mutant mice that fail to develop a TCA projection. These findings show that TCAs are not required for the establishment or maintenance of the graded and areal expression patterns of these genes and strongly suggest that their regulation is intrinsic to the developing neocortex.

Expression of brain-derived neurotrophic factor, neurotrophin-3 and their receptor messenger RNAs in monkey rhinal cortex

The primate rhinal cortex, consisting of areas 36 and 35 of the perirhinal cortex and the entorhinal cortex (area 28), plays a crucial role in perception and memory. We investigated the expression of messenger RNAs for brain-derived neurotrophic factor and neurotrophin-3, as well as those for their respective tyrosine kinase receptors, TrkB and TrkC, in the monkey rhinal cortex. Results from in situ hybridization revealed that each of these messenger RNAs was expressed in neurons with distinct laminar and areal patterns of distribution. Brain-derived neurotrophic factor messenger RNA was principally detected in layers V/VI of area 36, and layers II/III and V of the entorhinal cortex. Some of the messenger RNA-positive cells in the deep layers of the rhinal cortex were confirmed to exhibit a pyramidal cell-like morphology. Neurotrophin-3 messenger RNA expression was confined to layers II/III of the entorhinal cortex. In contrast, trkB and trkC messenger RNAs were expressed rather homogeneously and abundantly throughout the rhinal cortex. The laminar and cellular distributions of brain-derived neurotrophic factor and neurotrophin-3 messenger RNAs indicate the predominant expression of these neurotrophins in projection neurons. These results suggest that brain-derived neurotrophic factor and neurotrophin-3 regulate neuronal connectivities of forward and backward projections from the rhinal cortex and contribute to functional reorganization underlying the formation and maintenance of long-term memory in primates.

Predicting the identity and fate of plant invaders: Emergent and emerging approaches

Prediction of the potential for plant species to invade new ranges has long attracted the attention of ecologists motivated by both fundamental and practical considerations. Consequently, a conceptually diverse array of correlative and experimental approaches have been developed to predict the identity and fate of future invaders. The most straightforward approach has long involved simply compiling lists of species known to be aggressive either in their native range or a new range. Although these lists can be encyclopedic, they often fail to include species that have yet to become aggressive anywhere. As a result, much effort has been devoted instead to searching for commonality in the ecological traits of invading species as a predictive tool. Success in using such distillations is hampered by the emphasis on the traits of ruderals, despite the ability of non-ruderals to become naturalized, and the frequent inability to decipher which traits contribute to a species' naturalization from those that are merely coincidental with naturalization. The intuitively-appealing approach of identifying a region's future invaders among species that are aggressive in regions with a similar climate (‘climatic-matching’) fails to account for the often quite different biotic restrictions among regions with similar climates. A fourth correlative tool, predictions of an alien species' future distribution and prominence based on its initial rate of spread, is handicapped by our lack of comprehensive knowledge on the areal patterns and temporal course that invasions may follow. In contrast to these correlative tools, prediction has also been sought by determining the constraints of the physical environment on alien species in controlled-growth facilities and glasshouses. Although such facilities certainly provide instructive results, potential interactions between and among factors, especially biotic factors, are difficult to simulate. Three other experimental approaches offer a higher rate of prediction: simultaneous field comparisons between congeners (e.g. one naturalized, one native), and following the fate of a species deliberately sown in a natural community beyond its current range, with or without environmental manipulation. Evaluation of the efficacy of these last three approaches awaits their wider application. Although the experimental approaches hold greater promise, none is a panacea. Prediction will be the highest when several approaches are combined simultaneously (e.g. manipulating the environment for congeners in the field).

The impact of glaciation on the groundwater regime of Northwest Europe

Growth of mid-latitude ice sheets during the glacial cycles of the Quaternary repeatedly reorganises the pattern of groundwater flow on a continent-wide scale. Relatively small scale non-glacial catchments are replaced by catchments which are integrated on the scale of continental ice sheets. Simulations are presented of the response to glaciation of a large part of the western European groundwater system during the last two (Saalian, Weichselian) glacial cycles. A two-dimensional model along an ice sheet flowline from western Sweden to The Netherlands illustrates the impact of glaciation on flow in the vertical plane, and a vertically integrated model illustrates its impact on areal patterns of flow. Hydraulics heads, hydraulic gradients and flow velocities are increased far above their modern values, and relatively shallow aquifers are completely flushed out during glacial periods. There are significant implications for groundwater chemistry and geological structures. Large seepage pressures generated near to ice sheet margins and major impacts on the distribution of effective pressures will produce structures such as hydrofractures, sediment dykes, sediment volcanoes, loading structures etc. The model can be readily applied to hydrocarbon resorvoirs.