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Drainage Pattern (drainage + pattern)

Distribution by Scientific Domains

Earth and Environmental Science	35%
Medical Sciences	23%
Life Sciences	23%
Humanities and Social Sciences	11%

Selected Abstracts

Drainage patterns and tectonic forcing: a model study for the Swiss Alps

BASIN RESEARCH, Issue 2 2001
A. Kühni
ABSTRACT A linear surface process model is used to examine the effect of different patterns of rock uplift on the evolution of the drainage network of the Swiss Alps. An asymmetric pattern of tectonic forcing simulates a phase of rapid retrothrusting in the south of the Swiss Alps (,Lepontine'-type uplift). A domal pattern of tectonic forcing in the north of the model orogen simulates the phase of the formation of the ,Aar massif', an external basement uplift in the frontal part of the orogenic wedge (,Aar'-type uplift). Model runs using the ,Lepontine'-type uplift pattern result in a model mountain chain with a water divide in the zone of maximum uplift and orogen-normal rivers. Model runs examining the effect of ,Lepontine'-type uplift followed by ,Aar'-type uplift show that the initially formed orogen-normal river system and the water divide are both very stable and hardly affected by the additional uplift. This indifference to changes in tectonic forcing is mainly due to the requirement of a high model erosion capacity for the river systems in order to reproduce the exhumation data (high-grade rocks in the south of the Swiss Alps point to removal of a wedge-shaped nappe stack with a maximum thickness of about 25 km). The model behaviour is in agreement with the ancestral drainage pattern of the Alps in Oligocene and Miocene times and with the modern pattern observed in the Coast Range of British Columbia; in both cases river incision occurred across a zone of rapid uplift in the lower course of the rivers. The model behaviour does not, however, explain the modern drainage pattern in the Alps with its orogen-parallel rivers. When the model system is forced to develop two locally independent main water divides (simultaneous ,Lepontine'- and ,Aar'-type uplift), a zone of reduced erosional potential forms between the two divides. As a consequence, the divides approach each other and eventually merge. The new water divide remains fixed in space independent of the two persisting uplift maxima. The model results suggest that spatial and temporal changes in tectonic forcing alone cannot produce the change from the orogen-normal drainage pattern of the Swiss Alps in Oligocene,Miocene times to the orogen-parallel drainage observed in the Swiss Alps today. [source]

Venous Infarction of Brainstem and Cerebellum

JOURNAL OF NEUROIMAGING, Issue 4 2001
Yakup Krespi MD
ABSTRACT The authors describe 2 cases of posterior fossa venous infarction. A 56-year-old woman with essential thrombocytemia presented with fluctuating complaints of headache, nausea, vomiting, left-sided numbness-weakness, and dizziness and became progressively stuporous. Cranial magnetic resonance imaging (MRI) showed bilateral parasagittal frontoparietal and left cerebellar contrast-enhancing hemorrhagic lesions. On magnetic resonance venography, the left transverse and sigmoid sinuses were occluded. The second patient, a 39-year-old woman, presented with acute onset of diplopia, numbness of the tongue, vertigo, and right-sided weakness following a gestational age stillbirth. MRI revealed lesions in the right half of midbrain and pons and in the superior part of the right cerebellar hemisphere. Digital subtraction angiography showed right transverse and sigmoid sinus occlusion. The authors suggest that one should investigate the possibility of venous infarction in the presence of posterior fossa lesions that are often hemorrhagic and are not within any arterial territory distribution but respect a known venous drainage pattern. Recognition of the observed clinical and neuroimaging features can lead to earlier diagnosis and, potentially, more effective management. [source]

Moraine development at a small High-Arctic valley glacier: Rieperbreen, Svalbard

JOURNAL OF QUATERNARY SCIENCE, Issue 6 2001
Astrid Lyså
Abstract Ice-cored lateral and frontal moraine complexes, formed at the margin of the small, land-based Rieperbreen glacier, central Svalbard, have been investigated through field observations and interpretations of aerial photographs (1936, 1961 and 1990). The main focus has been on the stratigraphical and dynamic development of these moraines as well as the disintegration processes. The glacier has been wasting down since the ,Little Ice Age' (LIA) maximum, and between 1936 and 1990 the glacier surface was lowered by 50,60 m and the front retreated by approximately 900 m. As the glacier wasted, three moraine ridges developed at the front, mainly as melting out of sediments from debris-rich foliation and debris-bands formed when the glacier was polythermal, probably during the LIA maximum. The disintegration of the moraines is dominated by wastage of buried ice, sediment gravity-flows, meltwater activity and some frost weathering. A transverse glacier profile with a northward sloping surface has developed owing to the higher insolation along the south-facing ice margin. This asymmetric geometry also strongly affects the supraglacial drainage pattern. Lateral moraines have formed along both sides of the glacier, although the insolation aspect of the glacier has resulted in the development of a moraine 60 m high along its northern margin. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Tailoring donor hepatectomy per segment 4 venous drainage in right lobe live donor liver transplantation

LIVER TRANSPLANTATION, Issue 6 2004
See Ching Chan
Including the middle hepatic vein (MHV) in the right lobe liver graft for adult-to-adult live donor liver transplantation provides more functional liver by securing adequate venous drainage. Donor outcome of this procedure in relation to different venous drainage patterns of segment 4 is unknown. Modification of graft harvesting technique by preserving segment 4b hepatic vein (V4b) in theory compensates for unfavorable venous drainage patterns. Consecutive 120 right lobe live donors were included. Computed tomography was studied in detail to assign each donor to one of the three types of the Nakamura classification of venous drainage pattern of segment 4. Type I drainage was mainly via the left hepatic vein (LHV), type II drainage was equally into the MHV and LHV, and type III drainage was predominantly into the MHV. Any distinct umbilical vein was also noted. In the early part of the series, the V4b draining into the MHV was divided to provide a long MHV stump in the graft. In the later part of the series, prominent V4b draining into the MHV was preserved in the donor as far as possible. Donor outcomes were measured by peak values of prothrombin time (PT), serum bilirubin and transaminases levels. There was no donor mortality. Type I donors (n=69) had the best outcome with peak PT of 17.9 sec (range 12.3,23.3 sec). Type II donors (n=44) had peak PT of 18.5 sec (range 15.4,24.4 sec). When V4b was preserved in type II donors (n=19), the peak PT (18.0 sec, range 15.4,20.7 sec) became significantly lower than that of type II donors who had V4b sacrificed (20.3 sec, range 16.2,24.4 sec) (P=0.001). A distinct umbilical vein (n=91, 75.8%) was insignificant for donor outcome measured by peak PT. Multivariate analysis identified that type II donors with V4b sacrificed (n=25), type III donors (n=7), and the first 50 cases had less favorable outcomes. In conclusion, unfavorable venous drainage patterns were one of the independent factors compromising postoperative donor liver function, but was circumvented by preservation of V4b. (Liver Transpl 2004;10:755,762.) [source]

The Lymph Drainage Pattern of the Mammary Glands in the Cat: A Lymphographic and Computerized Tomography Lymphographic Study

ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 4 2009
P. L. Papadopoulou
Summary Seventy-three clinically normal, lactating cats were used to investigate the lymph drainage of 73 mammary glands. In 50 cats of the first group, the number of lymphatic vessels emerging from the examined mammary gland, their course and the lymph nodes into which they are drained were studied by indirect lymphography (IL) after intramammary injection of an oily contrast medium. In 23 cats of the second group, the lymph drainage of the mammary glands was studied by computerized tomography indirect lymphography (CT-IL) after intramammary injection of a water soluble contrast medium. The following day, the lymph drainage of the mammary gland examined by CT-IL was studied by IL, as it was described in the first group, for comparison purposes. The main conclusions drawn after this study were as follows: lymph drains from the first and second mammary glands with one or rarely two or three lymphatic vessels to the accessory axillary lymph nodes. Lymph drains from the third mammary gland with one or two and rarely three lymphatic vessels usually to the accessory inguinal lymph nodes or to the accessory axillary lymph nodes. In some cases, it drains to both lymph nodes simultaneously or it may rarely drain only to the medial iliac lymph nodes. The fourth mammary gland with one or two and rarely three lymphatic vessels usually drains to the accessory inguinal lymph nodes. It may rarely drain only to the medial iliac lymph nodes. Mammary lymphatic vessels that cross the midline and lymphatic connection between the mammary glands were not demonstrated. No differences in the mammary lymph drainage pattern between IL and CT-IL were found. [source]

Dynamics of extinction of a small population of the three-spined stickleback (Gasterosteus aculeatus L) caused by habitat modification

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2010
R. J. Wootton
Abstract 1.Abundance of a population of three-spined stickleback, Gasterosteus aculeatus L., in a small backwater of Afon Rheidol in mid-Wales (UK) was estimated annually each October from 1972 to 1999 by mark,recapture. 2.The population became extinct in 2000, because of land-use changes in 1995, which modified the drainage pattern through the backwater, causing the backwater to eventually dry up. 3.The final decline to extinction started from an estimated abundance of 1550 in 1998 and the abundance in 1999, the year before extinction, was 85. The smallest abundance from which the population showed an increase was 670. 4.Two years before extinction (1998), the population was characterized by an anomalously high proportion of small fish. 5.There was a significant power relationship between the years to extinction and population size, but if the data were analysed in two periods, 1972,1989 and 1990,1999, the relationship was only significant for the second period. 6.There was no relationship between time to extinction and per capita annual rate of increase (k), although values of k were unusually low in the last two years before extinction. 7.Time to extinction was not related to mean length, mean mass or the condition of the fish. 8.The results suggest that the indicators of impending extinction may vary with the causes of extinction and may be ambiguous, even when a long time-series of demographic data is available. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Drainage patterns and tectonic forcing: a model study for the Swiss Alps

Modern and ancient fluvial megafans in the foreland basin system of the central Andes, southern Bolivia: implications for drainage network evolution in fold-thrust belts

BASIN RESEARCH, Issue 1 2001
B. K. Horton
ABSTRACT Fluvial megafans chronicle the evolution of large mountainous drainage networks, providing a record of erosional denudation in adjacent mountain belts. An actualistic investigation of the development of fluvial megafans is presented here by comparing active fluvial megafans in the proximal foreland basin of the central Andes to Tertiary foreland-basin deposits exposed in the interior of the mountain belt. Modern fluvial megafans of the Chaco Plain of southern Bolivia are large (5800,22 600 km2), fan-shaped masses of dominantly sand and mud deposited by major transverse rivers (Rio Grande, Rio Parapeti, and Rio Pilcomayo) emanating from the central Andes. The rivers exit the mountain belt and debouch onto the low-relief Chaco Plain at fixed points along the mountain front. On each fluvial megafan, the presently active channel is straight in plan view and dominated by deposition of mid-channel and bank-attached sand bars. Overbank areas are characterized by crevasse-splay and paludal deposition with minor soil development. However, overbank areas also contain numerous relicts of recently abandoned divergent channels, suggesting a long-term distributary drainage pattern and frequent channel avulsions. The position of the primary channel on each megafan is highly unstable over short time scales. Fluvial megafans of the Chaco Plain provide a modern analogue for a coarsening-upward, > 2-km-thick succession of Tertiary strata exposed along the Camargo syncline in the Eastern Cordillera of the central Andean fold-thrust belt, about 200 km west of the modern megafans. Lithofacies of the mid-Tertiary Camargo Formation include: (1) large channel and small channel deposits interpreted, respectively, as the main river stem on the proximal megafan and distributary channels on the distal megafan; and (2) crevasse-splay, paludal and palaeosol deposits attributed to sedimentation in overbank areas. A reversal in palaeocurrents in the lowermost Camargo succession and an overall upward coarsening and thickening trend are best explained by progradation of a fluvial megafan during eastward advance of the fold-thrust belt. In addition, the present-day drainage network in this area of the Eastern Cordillera is focused into a single outlet point that coincides with the location of the coarsest and thickest strata of the Camargo succession. Thus, the modern drainage network may be inherited from an ancestral mid-Tertiary drainage network. Persistence and expansion of Andean drainage networks provides the basis for a geometric model of the evolution of drainage networks in advancing fold-thrust belts and the origin and development of fluvial megafans. The model suggests that fluvial megafans may only develop once a drainage network has reached a particular size, roughly 104 km2, a value based on a review of active fluvial megafans that would be affected by the tectonic, climatic and geomorphologic processes operating in a given mountain belt. Furthermore, once a drainage network has achieved this critical size, the river may have sufficient stream power to prove relatively insensitive to possible geometric changes imparted by growing frontal structures in the fold-thrust belt. [source]

Three-dimensional Evolutionary Models of the Qiongxi Structures, Southwestern Sichuan Basin, China: Evidence from Seismic Interpretation and Geomorphology

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2009
Qiupeng JIA
Abstract: Fold terminations are key features in the study of compressional fault-related folds. Such terminations could be due to loss of displacement on the thrust fault or/and forming a lateral or oblique ramp. Thus, high-quality seismic data would help unambiguously define which mechanism should be responsible for the termination of a given fault-related fold. The Qiongxi and Qiongxinan structures in the Sichuan Basin, China are examples of natural fault-propagation folds that possess a northern termination and a structural saddle between them. The folds/fault geometry and along-strike displacement variations are constrained by the industry 3-D seismic volume. We interpret that the plunge of the fold near the northern termination and the structural saddle are due to the loss of displacement along strike. The fault geometry associated with the northern termination changes from a flat-ramp at the crest of the Qiongxinan structure, where displacement is the greatest, to simply a ramp near the northern tip of the Qiongxi structure, without forming a lateral or oblique ramp. In this study, we also use the drainage pattern, embryonic structure preserved in the crest of the Qiongxinan structure and the assumption that displacement along a fault is proportional to the duration of thrusting to propose a model for the lateral propagation of the Qiongxinan and Qiongxi structures. Specifically, we suggest that the structure first initiated as an isolated fault ramp within brittle units. With increased shortening, the fault grows to link with lower detachments in weaker shale units to create a hybridized fault-propagation fold. Our model suggests a possible explanation for the lateral propagation history of the Qiongxinan and Qiongxi structures, and also provides an alternative approach to confirming the activity of the previous Pingluoba structure in the southwestern Sichuan Basin in the late Cenozoic. [source]

Palynological evidence for Pennsylvanian (Late Carboniferous) vegetation change in the Sydney Coalfield, eastern Canada

GEOLOGICAL JOURNAL, Issue 4 2010
Tatyana K. Dimitrova
Abstract The palynology of clastic samples from seven stratigraphical levels in the late Moscovian Sydney Mines Formation, exposed along the shore at Bras d'Or, Nova Scotia, has been investigated. Most of the samples were from roof shales of major coals; the one sample that was not yielded a much higher proportion of pollen derived from extra-basinal vegetation. The four stratigraphically lower roof shale samples yielded essentially similar palynological spectra, with 39,±,4% lycophytes, 9,±,4% sphenophylls, 23,±,4% tree-ferns, 12,±,4% other ferns and 5,±,3% cordaites. The palynology of the upper part of the investigated succession suggests a shift in vegetation towards one favouring more marattialean tree-ferns, cordaites and conifers, and fewer lycophytes. This correlates with changes in drainage patterns as the alluvial plain migrated seawards and thus changed water tables. No evidence was found to suggest significant climate change at this time. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Evaluating interactions between soil drainage and seedling performance in a restoration of Pinus sylvestris woodland, Scotland

GLOBAL ECOLOGY, Issue 2 2001
M. D. Crowell
Abstract 1,This paper evaluates the role of soil drainage in tree seedling performance at a site being restored from Calluna vulgaris moorland to Pinus sylvestris woodland, in Glen Affric, Scotland. The investigation focuses on the relationships between height of planted seedlings, type of ground vegetation and drainage conditions. 2,Slope, aspect, and soil depth were assessed as potential surrogates for direct measures of soil drainage, all of which were derived from digital terrain data. 3,Six variables related to drainage were recorded at 58 seedling locations and used in a factor analysis to understand links between soil moisture conditions, topographic variables and soil depth characteristics. 4,Factor analysis generated two factors that accounted for 70.5% of the variance in the correlation matrix of these variables: Factor 1 correlated strongly with variables that controlled peat accumulation and Factor 2 correlated strongly with topographic controls upon drainage patterns. 5,These two factors explained a significant amount of the variance in height of the Pinus seedlings planted at these locations. Significant differences were found between the factor scores associated with different types of ground vegetation, as well as between the seedling heights observed at locations with different vegetation types. 6,Multiple regressions were developed that indicated that slope, aspect, and soil depth were significant as independent variables in models where soil moisture content and aerobic soil depth were the dependent variables. [source]

Soil piping and catchment response

HYDROLOGICAL PROCESSES, Issue 12 2010
J. A. A. Jones
Abstract Over the 40 years, since soil piping was first considered to be a potential factor in the hydrological response of catchments, research has revealed a considerable amount about its hydrological role and its geographical, climatic and pedological distribution. Piping has been shown to be a major factor supporting the hypothesis that subsurface flow can be a significant contributor to quickflow by field experiments ranging from the United Kingdom to Canada, India and China. This research has demonstrated that, at least in some areas, soil pipes may contribute up to nearly 50% of stormwater discharge. Piping processes therefore merit inclusion within rainfall,runoff simulation models, but this has yet to be achieved. Some progress has been made in modelling pipeflow itself, but integration within a catchment model presents major problems, not least in quantifying or parameterizing the nature and distribution of pipe networks. The wider environmental implications of soil piping are also only just beginning to be recognized. These range from the effects of changing residence times on water chemistry, especially on the acidification of surface waters, to the effects of hillslope drainage patterns on soil development and vegetation diversity. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Biogeography and molecular phylogeny of the genus Schizothorax (Teleostei: Cyprinidae) in China inferred from cytochrome b sequences

JOURNAL OF BIOGEOGRAPHY, Issue 8 2006
Dekui He
Abstract Aim, To test a vicariant speciation hypothesis derived from geological evidence of large-scale changes in drainage patterns in the late Miocene that affected the drainages in the south-eastern Tibetan Plateau. Location, The Tibetan Plateau and adjacent areas. Methods, The cytochrome b DNA sequences of 30 species of the genus Schizothorax from nine different river systems were analysed. These DNA sequences were analysed using parsimony, maximum likelihood and Bayesian methods. The approximately unbiased and Shimodaira,Hasegawa tests were applied to evaluate the statistical significance of the shortest trees relative to alternative hypotheses. Dates of divergences between lineages were estimated using the nonparametric rate smoothing method, and confidence intervals of dates were obtained by parametric bootstrapping. Results, The phylogenetic relationships recovered from molecular data were inconsistent with traditional taxonomy, but apparently reflected geographical associations with rivers. Within the genus Schizothorax, we observed a divergence between the lineages from the Irrawaddy,Lhuit and Tsangpo,Parlung rivers, and tentatively dated this vicariant event back to the late Miocene (7.3,6.8 Ma). We also observed approximately simultaneous geographical splits within drainages of the south-eastern Tibetan Plateau, the Irrawaddy, the Yangtze and the Mekong,Salween rivers in the late Miocene (7.1,6.2 Ma). Main conclusions, Our molecular evidence tentatively highlights the importance of palaeoriver connections and the uplift of the Tibetan Plateau in understanding the evolution of the genus Schizothorax. Molecular estimates of divergence times allowed us to date these vicariant scenarios back to the late Miocene, which agrees with geological suggestions for the separation of these drainages caused by tectonic uplift in south-eastern Tibet. Our results indicated the substantial role of vicariant-based speciation in shaping the current distribution pattern of the genus Schizothorax. [source]

Tailoring donor hepatectomy per segment 4 venous drainage in right lobe live donor liver transplantation

Molecular systematics, biogeography and population structure of Neotropical freshwater needlefishes of the genus Potamorrhaphis

MOLECULAR ECOLOGY, Issue 3 2000
N. R. Lovejoy
Abstract Phylogenetic relationships of populations and species within Potamorrhaphis, a genus of freshwater South American needlefishes, were assessed using mitochondrial cytochrome b sequences. Samples were obtained from eight widely distributed localities in the Amazon and Orinoco rivers, and represented all three currently recognized species of Potamorrhaphis. The phylogeny of haplotypes corresponded imperfectly to current morphological species identities: haplotypes from P. guianensis, the most widespread species, did not make up a monophyletic clade. Geography played a strong role in structuring genetic variation: no haplotypes were shared between any localities, indicating restricted gene flow. Possible causes of this pattern include limited dispersal and the effects of current and past geographical barriers. The haplotype phylogeny also showed a complex relationship between fishes from different river basins. Based on the geographical distribution of clades, we hypothesize a connection between the middle Orinoco and Amazon via rivers of the Guianas. More ancient divergence events may have resulted from Miocene alterations of river drainage patterns. We also present limited data for two other Neotropical freshwater needlefish genera: Belonion and Pseudotylosurus. Pseudotylosurus showed evidence of substantial gene flow between distant localities, indicating ecological differences from Potamorrhaphis. [source]

Lymphatic Mapping and Sentinel Lymphadenectomy for 106 Head and Neck Lesions: Contrasts Between Oral Cavity and Cutaneous Malignancy,

THE LARYNGOSCOPE, Issue S109 2006
FACS, Francisco J. Civantos MD
Abstract Objectives: The objectives of this prospective series were to present our results in 106 sequential cases of lymphatic mapping and sentinel lymph node biopsy (SLNB) in the head and neck region and contrast the experience in oral cancer with that for cutaneous lesions. Hypotheses: SLNB has an acceptably low complication rate in the head and neck. Lymphatic mapping and gamma probe-guided lymphadenectomy can improve the management of malignancies of the head and neck by more accurate identification of the nodal basins at risk and more accurate staging of the lymphatics. For appropriately selected patients, radionuclide lymphatic mapping may safely allow for minimally invasive sentinel lymphadenectomy without formal completion selective lymphadenectomy. Methods: One hundred six patients underwent intralesional radionuclide injection and radiologic lymphoscintigraphy (LS) on Institutional Review Board-approved protocols and 103 of these underwent successful SLNB. These included 35 patients with malignant melanoma, 10 cutaneous squamous cell carcinomas, four lip cancers, eight Merkel cell carcinomas, two rare cutaneous lesions, and 43 oral cancers. Mean follow up was 24 months. Patients with oral cavity malignancy underwent concurrent selective neck dissection after narrow-exposure sentinel lymph node excision. In this group, the SLNB histopathology could be correlated with the completion neck specimen histopathology. Patients with cutaneous malignancy underwent SLNB alone and only received regional lymphadenectomy based on positive histology or clinical indications. Data were tabulated for anatomic drainage patterns, complications, histopathology, and patterns of cancer recurrence. Results: Surgical complications were rare. No temporary or permanent dysfunction of facial or spinal accessory nerves occurred with sentinel node biopsy. Lymphatic drainage to areas dramatically outside of the expected lymphatic basins occurred in 13.6%. Predictive value of a negative sentinel node was 98.2% for cutaneous malignancies (based on regional recurrence) and 92% with oral cancer (based on pathologic correlation). Gross tumor replacement of lymph nodes and redirection of lymphatic flow represented a significant technical issue in oral squamous cell carcinoma. Sixteen percent of patients with oral cancer were upstaged from N0 to N1 after extended sectioning and immunohistochemistry of the sentinel node. Conclusions: LS and SLNB can be performed with technical success in the head and neck region. Complications are minimal. More accurate staging and mapping of lymphatic drainage may improve the quality of standard lymphadenectomy. The potential for minimally invasive surgery based on this technology exists, but there is a small risk of missing positive disease. Whether the failure rate is greater than that of standard lymphadenectomy without gamma probe guidance is not known. New studies need to focus on refinements of technique and validation of accuracy as well as biologic correlates for the prediction of metastases. [source]

Fold evolution and drainage development in the Zagros mountains of Fars province, SE Iran

BASIN RESEARCH, Issue 1 2008
Lucy A. Ramsey
ABSTRACT A central question in structural geology is whether, and by what mechanism, active faults (and the folds often associated with them) grow in length as they accumulate displacement. An obstacle in our understanding of these processes is the lack of examples in which the lateral growth of active structures can be demonstrated definitively, as geomorphic indicators of lateral propagation are often difficult, or even impossible to distinguish from the effects of varying lithology or non-uniform displacement and slip histories. In this paper we examine, using the Zagros mountains of southern Iran as our example, the extent to which qualitative analysis of satellite imagery and digital topography can yield insight into the growth, lateral propagation, and interaction of individual fold segments in regions of active continental shortening. The Zagros fold-and-thrust belt contains spectacular whaleback anticlines that are well exposed in resistant Tertiary and Mesozoic limestone, are often >100 km in length, and which contain a large proportion of the global hydrocarbon reserves. In one example, Kuh-e Handun, where an anticline is mantled by soft Miocene sediments, direct evidence of lateral fold propagation is recorded in remnants of consequent drainage patterns on the fold flanks that do not correspond to the present-day topography. We suggest that in most other cases, the soft Miocene and Pliocene sediments that originally mantled the folds, and which would have recorded early stages in the growth histories, have been completely stripped away, thus removing any direct geomorphic evidence of lateral propagation. However, many of the long fold chains of the Zagros do appear to be formed from numerous segments that have coalesced. If our interpretations are correct, the merger of individual fold segments that have grown in length is a major control on the development of through-going drainage and sedimentation patterns in the Zagros, and may be an important process in other regions of crustal shortening as well. Abundant earthquakes in the Zagros show that large seismogenic thrust faults must be present at depth, but these faults rarely reach the Earth's surface, and their relationship to the surface folding is not well constrained. The individual fold segments that we identify are typically 20,40 km in length, which correlates well with the maximum length of the seismogenic basement faults suggested from the largest observed thrusting earthquakes. This correlation between the lengths of individual fold segments and the lengths of seismogenic faults at depth suggest that it is possible, at least in some cases, that there may be a direct relationship between folding and faulting in the Zagros, with individual fold segments underlain by discrete thrusts. [source]