Short-term Episodes Research Articles

Sexuality and reproduction in bulimia nervosa patients over 10 years

The reproductive and sexual histories of women who had recovered or were recovering from bulimia nervosa were examined. Of 48 consecutive female patients, 43 were studied 10–15 years after first presenting for treatment. At follow-up, 74% were considered recovered and 26% still had an eating disorder. Only 2 women fulfilled the criteria for bulimia nervosa. A history of amenorrhea was common (81% of women), 63% of women being without their menstrual periods for more than 12 months. Menstruation was present in women at a body mass index of 19 or more who were no longer using the weight loss practices of self-induced vomiting, laxative abuse, and starvation. Bulimia nervosa women are more likely to be investigated for infertility when their eating disorder is active. Bulimia sufferers are sexually active, but have times of withdrawing from their partners and ceasing sexual behavior. They associate their sexual feeling with body weight, pregnancy, breastfeeding, and status of their relationships. Marital breakdown is also more common but only if the eating disorder was active at the time of marriage. Forty-five percent felt their relationship had a negative effect on their eating disorder. Short-term episodes of bulimic-free behavior are associated with pregnancy and breastfeeding in some pregnancies. Termination of pregnancy occurs more often. The prevalence of miscarriage, hyperemesis gravidarum, and postnatal depression was greater among women who had not recovered from their eating disorder at the time of their pregnancy. Recovery from eating disorder behavior before attempting conception reduces the prevalence of the gynecologic, obstetric, and psychiatric problems associated with eating disorder behavior.

Hypoxia adaptation in fish of the Amazon: a never-ending task

In addition to seasonal long-term changes in dissolved oxygen and carbon dioxide, water bodies of the Amazon present periodic short-term episodes of hypoxia and even anoxia. To preserve gas exchange and acid base balance, fish of the Amazon have developed multiple adaptive solutions which occur at all biological levels. These solutions are thought to represent adaptive convergence rather than phylogenetic relatedness. Fish of the Amazon exposed to different experimental conditions adjust, for example, several parameters to improve oxygen transfer from the gas-exchange site to the tissues. These parameters include morphological changes such as the development of the lower lip in Colossoma, changes in ventilation rates, changes in circulatory parameters, increased circulating red blood cells, decreased levels of intraerythrocytic phosphates, and adjustments of intraerythrocytic pH (pHi). These adjustments that allow fish to survive both short- and long-term hypoxia occur in different degrees in different fi...

Evidence of episodic fluid, gas, and sediment venting on the northern Gulf of Mexico continental slope

Surficial sediments and sea-floor features of the northern Gulf of Mexico continental slope record dramatic episodic venting and slower seepage of formation fluids, brines, crude oil, gases, and fine-grained sediments. Faults, activated by massive sediment input during periods of Plio-Pleistocene falling to low sea levels accompanied by compensating salt movement, provide avenues of vertical transport to the continental slope surface. Many of these faults cut thick sedimentary sequences that frequently contain geopressured zones which provide the driving force for fluid and gas expulsion. Flux rate and fluid characteristics are interpreted as important determinants of modern sea-floor geology and biology. Qualitatively, under conditions of rapid flux of sediment-rich fluids, mud volcanoes (up to 1 km wide and 50 m high) and extensive sheets of extruded mud result. These sediments contain old and displaced microfaunas. Muds are frequently extruded with large volumes of crude oil and gas (both biogenic and thermogenic). In water depths greater than approximately 500-m rapid to moderate vertical flux of hydrocarbon gases and fluids results in the construction of relief features composed of gas hydrates, ejected mud, and authigenic carbonates. Areas with near-surface hydrates frequently support complex chemosynthetic communities with associated hardgrounds containing calcareous remains of mussels, clams, and associated gastropods. Slow flux (seeps) promotes the formation of 13 C-depleted carbonate hardgrounds, stacked carbonate slabs, and moundlike carbonate buildups (frequently >20-m relief). Barite along with carbonate has been found in areas where rapid flux of sediment-carrying fluids has waned in the recent past and mineral-rich brines are now being ejected. Crests, chimneys, and cones of these minerals are found in such settings. Both recent numerical simulations of fluid release from geopressured zones and direct observations at the sea floor support a pattern of episodic venting. Short-term episodes of venting are probably regulated by fault movement, perhaps controlled by local salt adjustment. Destabilization of gas hydrates by oceanographic processes also causes short-term episodic gas expulsion. These events occur with interannual to intra-annual frequencies. Longer gas hydrate stabilization-destabilization cycles in continental margin settings are forced by hydrostatic loading and unloading at the frequency of sea-level change. Radiometric dating suggests that other long-term episodes of venting and major venting expulsion events are also probably modulated by sea- level change, time scales of thousands of years in response to low-stand sedimentary loading. Results of this summary of vent-seep-related phenomena suggest that sediment input from the shelf margin associated with cyclic Plio-Pleistocene falling to low sea-level periods, followed by major listic fault and salt adjustments to a new sediment load have activated venting-seepage throughout this period and perhaps longer.

Prevention of ischemic disturbances of contractile function of isolated heart by short-term total ischemia episodes

Short-term total ischemia episodes restrict the drop in the force and rate of contractions of isolated rat heart during long-term reperfusion period after long-term ischemia.

Short-term physiological responses of mosses to atmospheric ammonium and nitrate

Many bryophytes rely to a large extent on atmospheric deposition for their nutrient uptake. However, increasing levels of atmospheric ammonium (NH 4 + ) and nitrate (NO 3 - ) attract concern as to the possible harmful effects on bryophytes from these two nutrient sources. Changes in nitrate reductase (NR) activities, cation (Ca, K and Mg), total nitrogen (N) and organic acid concentrations were investigated for the mosses,Racomitrium lanuginosum, Rytidiadelphus loreus andPhilonotis fontana, in response to a single field misting with 3 mol−3 NH 4 + and NO 3 - . Increases of 20% were recorded for tissue N content, 48 hr after misting with N containing solutions. When labelled15NH 4 + or15NO 3 - were applied toR. Lanuginosum at 1, 3 and 6 mol m−3 concentrations, partitioning of incorporated15N between different tissue regions occured, with the highest N uptake in the upper stem and leaves. High concentrations of applied N resulted in reduced efficiency of N uptake. NH 4 + applications caused declines in NR activities, organic acids and cations, whereas, NO 3 - treatments caused the reverse response. Changes in cation contents, organic acids and NR activity reflect short-term regulation of N metabolism in the presence of defined N sources, as well as potential mechanisms of regulating cell pH homoeostasis. The consistency of physiological responses, especially NR activities, over short-term pollution episodes, provides evidence for their use as indicators of both NH 4 + and NO 3 - pollution.

Archeological Testing of Sites 41WB437 and 41WB438 Webb County, Texas

Archeological sites 41WB437 and 41WB438 are two prehistoric sites situated on opposing terraces of San Idelfonso Creek at the crossing of U.S. Highway 83, approximately 7.5 km south of Laredo, Texas, and 0.6 km upstream from the confluence of the stream and the Rio Grande River. Site 41 WB438 is characterized by a relatively dense accumulation of lithic debris and occasional groundstone fragments scattered across a broad alluvial terrace on the south side of the stream. Site 41WB437 is characterized by a much sparser scatter of cultural material on the north terrace. Both sites, but in particular 41WB438, have been heavily modified at the surface by historic activity. Archeological significance testing of the portion of these two sites in the R-O-W of US Highway 83 was conducted by TxDOT personnel in late March and early April, 1997, using a combination of mechanically-excavated and hand-excavated units. The results of testing indicate that site 41WB437 is underlain by thick, silty late Holocene alluvial unit that contains a number of ephemeral, relatively high integrity cultural strata to depths of at least 2 m below the ground surface. While the cultural material associated with these occupations is not particularly abundant, the presence of preserved burned rock features with associated charcoal, bone, shell, and lithic debris suggests that the site has the potential to yield important subsistence and technological information relevant to discrete, short term episodes of cultural activity. Therefore, the site is considered eligible for nomination to the National Register of Historic Places and for designation as a Texas State Archeological Landmark. Because avoidance is impractical, a mechanically-assisted block excavation focused on exposure and documentation of one or more broad occupation surfaces in the upper 1.5 m of the deposit is recommended to mitigate impacts to the site. Site 41WB438, in contrast, consists of a thin veneer of the same late Holocene alluvial fill resting on a much older, culturally sterile alluvial fill. Cultural material is lightly dispersed through the upper 50 cm of the terrace fill, but appears to be in poor stratigraphic context. However, it is possible that intact deposits are preserved in the unexamined portion of the site, which lies to the west of the R-O-W. Therefore, while the site cannot be ruled ineligible, no significant impact to the site's data potential will occur as a result of planned construction activities, and no further archeological work is recommended within the R-O-W.

Increased contribution of N-methyl-D-aspartate receptors to synaptic transmission inCA1 area of the rat hippocampus after short-term episodes of hypoxia/aglycemia

Effect of hypoxia/aglycemia episodes on excitatory postsynaptic currents (EPSC) evoked in pyramidal neurons of the rat hippocampalCA1 area by electrical stimulation of Schaffer collaterals was studied using voltage-clamp and intracellular perfusion techniques. By 60–80 min after a 10-min-long hypoxia/aglycemia episode, the EPSC amplitude increased and the EPSC decay was considerably slowed down, if compared with control. In contrast to control conditions, under which EPSC decay kinetics did not depend on the stimulus strength, hypoxia/aglycemia was followed by slowing down of the EPSC decay when stimulus intensity increased. The stimulus-dependent posthypoxic “slow” EPSC component was depressed both by D-(−)-2-amino-5-phosphonovaleric acid, an NMDA receptor blocker, and by 6-cyano-7-nitroquinoline-2,3-dion, a non-NMDA receptor blocker, which suggested possible polysynaptic origin of the above EPSC component. We suggest that short-term hypoxia/aglycemia transforms into an active state the NMDA receptors in the synapses of excitatory reccurrent collaterals of theCA1 hippocampal area, which had not functioned before. An increase in the intracellular calcium concentration from 1.5 to 5.0 mM resulted in the effect similar to that produced by hypoxia/aglycemia, which suggests that calcium channels play an important role in the mechanisms responsible for hypoxia-related activation of “silent” NMDA receptors.

Winter oceanographic conditions and water mass balance in the Northern Adriatic (February 1993)

Abstract In February 1993 a hydrographic campaign was undertaken in the northern Adriatic on a station network with 5 nM resolution. An interval of more than two weeks, prior to and during the campaign, was characterized by calm weather and small variability in air temperature and atmospheric pressure. The Po river run-off, which can also strongly affect the northern Adriatic circulation pattern, in January 1993 was lower than the long-term average without any short-term high run-off episodes. In the horizontal distribution of temperature and salinity two parallel N-S fronts were observed: one about 20 km from the Italian coast separating colder and fresher surface water of the Po origin from the sea ambient waters, the other frontal zone separates saltier and warmer water advected from south from waters of the basin interior. In the density field only the western surface front, associated with the freshwater inflow, is evident. From the Brunt-Vaisala frequency profiles internal Rossby radii of deformation were calculated for each CTD station. Horizontal distribution of internal radii of deformation closely follows surface isopycnals suggesting that horizontal scales are determined mainly by the freshwater induced stability of the water column. The first Rossby radius of deformation varies from about 1 km in the basin interior to 17 km near the Po estuary where the vertical stability reaches maximum. The vertical structure of the first mode eigenfunction is closely related to the freshwater spreading and saltier water advection from the south. An attempt was made to estimate the water inflow from the south assuming the geostrophic balance. A return flow driven by compensating mechanisms to the geostrophically balanced outflow was found to be of the same order of magnitude as the Po discharge.

Distinct modes of melatonin secretion in normal men

As for many hormones, melatonin levels in the blood suggest that it is discharged from the pineal gland in a pulsatile manner. Recently, the existence of short-term episodes, superimposed on the circadian pattern of circulating melatonin, has been questioned. Because plasma melatonin levels reflect not only the secretory process, but also the effects of distribution and degradation, secretory rates were estimated from peripheral levels, using a deconvolution procedure. Fourteen healthy volunteers were studied during the night, while sleeping in the dark (2300-0700), and seven of them subsequently were used in a replicate study. Plasma melatonin levels were measured at 10-min intervals by a direct, specific radioimmunoassay. Pulse analysis was performed using the computer program ULTRA. Approximately 30% more pulses were detected on the overall secretory were often superimposed on tonic basal secretion. Their number, amplitude, and distribution over time were variable depending on subjects. Also the mean melatonin secretory rate varied more than threefold across individuals. Despite the large interindividual variability, the subjects, who were used in replicate experiment, displayed a rather similar secretory profile. We conclude that in normal adult men, melatonin secretion undergoes two distinct secretory modes, in which episodic secretion is superimposed on tonic secretion in subject-dependent variable proportions.

Water quality requirement of Atlantic salmon (Salmo salar) in water undergoing acidification or liming in Norway

Atlantic salmon are severely affected by acidification in Norway. Water quality criteria for the salmon have to be based on the most sensitive stage, the smolt stage. The sensitivity to acidic water increases enormously during smolting, the seawater tolerance being especially vulnerable. Even moderately acidic water (pH about 6) with low inorganic monomeric aluminium (LA1) concentrations (<20μg. L−1) and short-term episodes may be harmful. Mixing zones in limed or unlimed rivers may also represent a problem for seaward migrating smolts. In limed salmon rivers, the national liming goal has been increased to pH 6.5 during smolting (1 February to 1 July) and to 6.2 the rest of the year as a result of our experiments. In contrast to what has been found for brown trout, salmon strains originating from watercources undergoing acidification were not more tolerant than those from non-acidic watercourses. At the moment no such “tolerant” strains are available for restocking limed rivers in Norway.

Outpatient psychotherapy in the United States, II: Patterns of utilization

The purpose of this article is to characterize the use of psychotherapy based on episode duration. Data were analyzed from the household section of the 1987 National Medical Expenditure Survey. The authors determined the demographic characteristics, provider and reason for visit distribution, mental and physical health status, and expenditures associated with very short-term (one to two sessions), short-term (three to 10 sessions), intermediate-term (11 to 20 sessions), and long-term (> 20 sessions) psychotherapy. Long-term psychotherapy accounted for 15.7% of psychotherapy users and 62.9% of total psychotherapy expenditures. Age above 65 years, black race, and less than 12 years of education decreased the likelihood of receiving long-term psychotherapy. Whereas long-term psychotherapy episodes tended to be provided by the specialty sector (65.7%) for specific mental conditions (53.8%), very short-term episodes were predominantly provided by the general medical sector (72.2%) for general medical or unspecified conditions (68.3%). Psychotropic medication use and, to less extent, psychiatric hospitalization tended to be more common among longer- as opposed to shorter-term users. Long-term and short-term psychotherapy tend to be provided by different health care professionals for the treatment of different types of health conditions. To help ensure the future of third-party payment for long-term psychotherapy, research is needed to better define the conditions under which long-term psychotherapy achieves benefits that equal or surpass those of other medical services or procedures of similar cost.

Tidal wetland record of holocene sea-level movements and climate history

Paleontological, geochemical, and lithological indicators of former marine and nonmarine influence are correlated between 13 cores from a tidal wetland (Wolfe Glade) on the southeast coast of Delaware Bay. Twenty new radiocarbon dates are used to establish the chronostratigraphy of marsh facies. Sediment iron content, weight loss on ignition, and remains of plants, diatoms and foraminifera (known to tolerate specific tidal inundation cycles) are used to describe cored facies originating from supratidal, intertidal and subtidal salt marsh subenvironments. Pollen assemblages are used to infer local Holocene climate fluctuations and to reconstruct paleoenvironments during marsh evolution. The record of paleoclimatology suggests the Atlantic Chron was warm with variable humidity in the region, whereas the Subboreal was dominated by cool and humid conditions. The Subatlantic was warmer, and initially dryer, with a cool humid phase prior to about 1 ka, returning to warmer, humid conditions in the last several centuries. Local relative sea-level movements are characterized by five rapid, short-term episodes when the rate of sea-level rise accelerated relative to the rate of marsh aggradation. These episodes are recorded by transgressive facies contacts at 5.3 ± 0.2 ka, 4.4 ± 0.2 ka, 3.25 ± 0.2 ka, and 1.8 ± 0.2 ka, sidereal years. An earlier transgressive facies contact dated 6.9 ± 0.2 ka is probably not the product of a true sea-level movement. Sea-level movements are recorded throughout the marsh as palustrine or high marsh peats or peaty overlain by lower intertidal or subtidal marine deposits. Several features suggest that these episodes are local relative transgressions produced by short-term accelerations in the rate of sea-level rise relative to marsh aggradation: the contemporaneity and apparent suddenness of marine inundations: the sequence of facies indicating marine drowning; the presence of similar events in marshes elsewhere in Delaware Bay; and the marsh-wide extent of indicative facies transitions. We propose that the rapid and frequent sea-level movements observed in Wolfe Glade are the result of surges and relaxations in the Gulf Stream (and associated spin-up and partial collapse of the North Atlantic gyre) in response to winds generated by changes in the North Atlantic atmospheric thermal gradient associated with Holocene climate fluctuations.

Compromised Hormonal Counterregulation, Symptom Awareness, and Neurophysiological Function After Recurrent Short-Term Episodes of Insulin-Induced Hypoglycemia in IDDM Patients

To test the hypothesis that recurrent short-term hypoglycemic episodes may impair hormonal counterregulation, symptom awareness, and neurophysiological function during subsequent hypoglycemia, we examined two groups of IDDM patients (n = 18), neither of whom exhibited signs of autonomic neuropathy. Two sequential euglycemic-hypoglycemic clamp studies were performed three days apart with stable glycemic plateaus of 5.6, 3.3, 2.2, and 1.7 mM, at which the patients' awareness of and response to hypoglycemia was evaluated. In the intervention group (n = 11), three short-term hypoglycemic episodes preceded the second clamp study. Counterregulatory hormones increased significantly during hypoglycemia, but adrenaline (P < 0.03), cortisol (P < 0.01), and ACTH (albeit not significant) showed a blunted response after repetitive hypoglycemic events. In this group, the perception of hypoglycemic symptoms was significantly reduced and was most evident for the autonomic symptoms of sweating (P < 0.05), heart pounding (P < 0.01), and warmness (P < 0.03). The deterioration of neurophysiological function, as assessed from the middle latency auditory evoked potentials, was more pronounced in the intervention group (latency shift of the Pa component, P < 0.05). These data suggest that alterations of neuroendocrine counterregulation, symptom perception, and certain aspects of cerebral function may occur as a consequence of recurrent short-term hypoglycemic episodes. These adaptation phenomena may contribute to the increased incidence of severe hypoglycemia in IDDM patients on intensive insulin therapy.

Compromised hormonal counterregulation, symptom awareness, and neurophysiological function after recurrent short-term episodes of insulin-induced hypoglycemia in IDDM patients

Compromised hormonal counterregulation, symptom awareness, and neurophysiological function after recurrent short-term episodes of insulin-induced hypoglycemia in IDDM patients

Enhanced particle fluxes in Bay of Bengal induced by injection of fresh water

THE melting of ice sheets during deglaciation results in the injection of large amounts of fresh water into the oceans1. To investigate how such injections might influence particle fluxes in the ocean, and hence the uptake of atmospheric CO2, we deployed three sediment-trap moorings (two traps in each mooring) in the northern, central and southern parts of the Bay of Bengal, respectively. The Bay of Bengal is suitable for such a study, because some of the world's largest rivers2 supply pulses of fresh water and sediment to the bay, resulting in large seasonal changes in surface salinity3. We find that the maximum river discharge, which occurs during the southwest monsoon, coincides with the maximum observed flux of participate matter. From north to south, the carbonate flux increases, whereas fluxes of opal, organic carbon and particulate matter decrease. The overall flux pattern seems to be controlled by the seasonally varying input from the rivers and the accompanying shift in marine biogenic production. We conclude that fresh-water pulses during deglaciation may therefore have caused similar shifts in marine biogenic production, resulting in short-term episodes of increased oceanic uptake of atmospheric CO2.

Review of fetal cardiovascular and metabolic responses to diabetic insults in the pregnant ewe.

Studies with pregnant sheep are reviewed, which were designed to investigate whether short-term episodes of maternal hyperglycemia or hyperketonemia were detrimental to the fetus, whether ketones can cross the ovine placenta, and whether the combination of maternal hyperglycemia and hyperketonemia would contribute to an increased risk of fetal morbidity. It is concluded that acute increases in maternal ketones appear to be more detrimental to the fetus than acute increases in maternal glucose, as assessed by fetal cardiovascular, metabolic, and blood gas changes.

Deep‐tow and sea beam studies of dueling propagating ridges on the East Pacific Rise near 20°40′S

Nontransform ridge axis discontinuities, such as propagating rifts, overlapping spreading centers (OSCs) and saddle points, occur frequently along the mid‐ocean ridge system. We used Sea Beam and deep‐tow to study an example of a relatively large nontransform offset near 20°40′S on the East Pacific Rise (EPR). The two spreading center tips are 15 km apart and separated by a diffuse shear zone. A broad V‐shaped wake of disturbed topography and magnetics occurs on the flanks of the EPR near the offset. On a fine scale, the offset is tectonically much more complex than either the typical OSC or propagating rift structures for two reasons. First, it is a “dueling propagator” in which structures produced by successive short‐term episodes of northward and southward propagation have overprinted each other, with migration toward the south prevailing over the long term. Second, its offset distance is such that its tectonic behavior may be transitional from that of a propagating rift to that of an OSC system. The offset's rate of migration to the south has been ∼20 mm/yr over the last 2 m.y., far less than total opening rate of 162 mm/yr. Distinct propagation events may have been much more rapid, however, surging north and south at rates of 160–230 mm/yr. In the process, several fossil spreading ridges 30–50 km long have been abandoned and rafted to the side. We propose a fine scale tectonic evolution in which a propagating spreading center either curves inside or runs outside of a soon to be abandoned, propagating rift tip. We call this process “self‐decapitation.” Dueling propagation at 20°40′S may be caused by competing magmatic sources at shallow points along the EPR: one to the north near 20°S and one to the south near 21°30′S. The 20°40′S dueling propagator occurs at a long‐wavelength low in the axial depth profile between these competing sources. In general, the division of spreading centers into segments separated by ridge axis discontinuities occurs at low points along the axis and may be caused by the pattern of upper mantle convection and the factors governing flow of magma along the strike of the ridge.

Apprenticing a Career

Anthropology & Education QuarterlyVolume 14, Issue 3 p. 184-187 Free Access Apprenticing a Career Murray L. Wax, Murray L. Wax Professor of Sociology, Visiting Distinguished Professor Social Sciences Washington University, College of St. ThomasSearch for more papers by this author Murray L. Wax, Murray L. Wax Professor of Sociology, Visiting Distinguished Professor Social Sciences Washington University, College of St. ThomasSearch for more papers by this author First published: Fall 1983 https://doi.org/10.1525/aeq.1983.14.3.05x1705oAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Volume14, Issue3Fall 1983Pages 184-187 RelatedInformation

Bone response to phosphate salts, ergocalciferol, and calcitriol in hypophosphatemic vitamin D-resistant rickets.

We treated 11 children with vitamin D-resistant rickets with a phosphate mixture either alone (1.2 to 3.6 g per day) or combined with ergocalciferol (vitamin D2, to 50 x 103 IU per day) or with calcitriol (1,25-dihydroxyvitamin D3, 0.25 to 1 microgram per day). Serum calcitriol concentrations were normal in all patients. Calcitriol therapy circulating levels of the hormone to values above normal and increased intestinal phosphate absorption. In some patients this regimen decreased the need for phosphate supplements. None of the treatment regimens corrected the renal phosphate leak. Radiologic studies and bone histomorphometric analyses showed that phosphate (alone or with ergocalciferol) induced the mineralization of the growth plate but not of the endosteal bone surface. Combined calcitriol and phosphate therapy for a total of 2850 patient-days greatly improved the mineralization of trabecular bone. Short-term episodes of hypercalcemia were easily controlled by changes in calcitriol dosage. The data indicate that the combined calcitriol and phosphate regimen is useful in the treatment of vitamin D-resistent rickets.

The geological evolution of Europe

This address represents a foolhardy and idiosyncratic summary of the geological evolution of Europe from its earliest records in the rocks of the Fenno-Scandian shield to the sediments accumulating in its modern seas. The general theme is the periodic mountain-building episodes, each of which is thought to relate, in general terms, either to the Atlantic line or to the Mediterranean line. Proterozoic movements, the various phases of the Caledonian orogeny and certain later events were clearly related to the Atlantic. The Variscan orogeny was the prelude to the Alpine and both related to the Mediterranean /Tethys. Most of the major lineaments of Europe, and many of the minor ones, are thought to be very ancient features. These in turn relate to the movement of crustal plates which periodically separated and brought together Europe, North America and Africa. Short-term episodes of plate convergence were separated by long-term periods of crustal stability when particular types of sedimentary rocks, especially limestones and continental deposits, were laid down over remarkably large areas. The process continues.