Analysis Of Drainage Patterns Research Articles

Quaternary landscape evolution in the Western Argentine Precordillera constrained by 10Be cosmogenic dating

Alluvial fans of the western piedmont of the Western Argentine Precordillera developed during the Early-Middle Pleistocene are excellently preserved markers of Quaternary-active structures, such as the N-S strike-slip El Tigre Fault and minor piedmont faults and folds. A temporal model was obtained to evaluate the Quaternary tectonic and climatic control on the landscape evolution by integrating alluvial fan exposure ages (10Be), topographic scarp measurements, fluvial morphometry data, and slip rates. Geomorphic features and cosmogenic dating (10Be) allowed identification of five alluvial abandonment events: 1) Q5: 926 ± 38 ka; 2) Q4: 767 ± 29 ka; 3) Q3: 592 ± 54 ka; 4) Q2: 352 ± 27 ka; and 5) Q1: 258 ± 23 ka. This chronology suggests that alluvial fan systems typically became inactive at the beginning of or during interglacial periods. Thus, aggradation seems to have occurred during glacial stages and dissection during interglacial ones. Inset alluvial fan surfaces suggest a sustained base-level lowering linked to low-rate regional uplift superimposed onto the climatic control. Topographic scarp measurements and 10Be exposure ages allowed estimation of intermediate-term (105–106 y) slip rates linked to six neotectonic events during the Pliocene and Early-Middle Pleistocene. Longitudinal river profiles and drainage pattern analysis constrained by 10Be exposure ages confirmed that the El Tigre Fault has tectonically controlled the fluvial network since the Middle-Pleistocene. A Holocene tectonic event was recorded by the presence of a current rectangular drainage pattern, numerous knickpoints and highest channel steepness index (Ksn), spatially associated and controlled by the minor piedmont scarps. The current drainage pattern and main river profiles show a stable and mature configuration. However, the landscape is still developing, being rejuvenated by piedmont structures and by the Quaternary activity of the Sierra del Tigre backthrust. Uplifts and shortenings for the El Tigre Fault scarp ranged from 0.454 ± 0.088 to 0.661 ± 0.130 and 0.122 ± 0.024 to 0.241 ± 0.047 mm/a, respectively, in agreement with estimates from similar structures of the Precordillera. Uplifts and shortenings for minor piedmont fault and fold scarps ranged from 0.009 ± 0.001 to 0.049 ± 0.005 and from 0.004 to 0.028 ± 0.003 mm/a, respectively. Our results confirm that the alluvial fan surfaces and the current fluvial landscape are driven by both tectonic and climatic controls. Finally, we propose that Quaternary-active structures accommodate part of the crustal shortening in the Pampean flat-slab segment, although the study area represents a backthrust zone of the current deformation front.

Water resources exploration and management based on remote sensing and geophysical data analysis: Al-Naqab Watershed, East Central Sinai, Egypt

This study integrates remote sensing and geophysical data to identify the hydrological conditions of the Naqab reservoir watershed. The main objectives of this study are identification and the interpretation of subsurface structures and their impact on groundwater flow, the relationships between structures and groundwater and the optimum way for watershed management in this sub-basin. Geophysical data including, ground magnetic survey and 1D electrical resistivity sounding helped in identifying the lithology and delineating zones of groundwater occurrence. The magnetic data delineated the basement rock, aided in characterizing the geometry of the subsurface structures that control the land surface features and constrain groundwater flow system. The interpreted subsurface structure elements include six sets of faults trending NE-SW, NW-SE, NWW-SEE, NEE-SWW, N-S and E-W. The basement depth was estimated at zero at the southern part and about 5187 m at the northern part. Two aquifer systems were characterized, the shallow aquifer of the Wata Formation (Upper Cretaceous) and the deep aquifer of the Malha Formation (Lower Cretaceous). The probability of groundwater occurrence increases towards the central part of the study area to north direction, where the thickness of the sedimentary basin reaches its maximum at the center of the study area. Different trends of faults were interpreted from are the geo-electrical cross-sections along two transects. Three patterns of faults were characterized including step faults, graben faults and horst faults. These faults could be indicated on the geo-electrical section by a marked difference in the layers` thicknesses. The magnetic data confirmed the locations of the faults delineated by the electrical resistivity profiles. The outlined faults are trending mainly in NE-SW, NW-SE, NWW-SEE, NEE-SWW and E-W directions. Lineament structures delineation and drainage pattern analysis were evaluated and interpreted from the analysis of remote sensing (RS) data and geographic information system (GIS) technique. The SRTM-DEM (Shuttle Radar Topographic Mission-Digital Elevation Model) was also utilized to automatically identify and extract drainage network. Interpretation and analysis of the inferred lineament structures indicate the presence of a number of main lineament populations that trends: NE-SW, NW-SE, NNW-SSE, NWW-SEE, E-W and N-S. Meanwhile, the interpretation and analysis of drainage pattern network indicate the presence of three main lineament structures that trends: NW-SE, NE-SW and NWW-SEE. Azimuth distribution analysis of both the measured structures and drainage channels shows similar trends, except for very few differences in the prevailing trends. Similarity in orientation of lineament structures, drainage system, and subsurface structural trends were recognized in the area under study. In conclusion, the integration between remote sensing and geophysical data revealed a close matching between the surface structural lineaments and subsurface structural trends could be verified. The preferred conduits of surface run-off and groundwater flow, as well as, the proper locations for groundwater exploitation could be determined.

Venous drainage pattern analysis of medial sphenoid wing meningiomas related to surgical planning

Venous drainage pattern analysis of medial sphenoid wing meningiomas related to surgical planning

Groundwater quality assessment in the Lower Ganga Basin using entropy information theory and GIS

Mapping and managing groundwater resources are essential for socio-economic and sustainable development. Analysis of hydrogeochemical parameters of the groundwater for the Lower Ganga basin is presented to identify the contamination zones and also to understand the groundwater quality in this region. Drainage pattern analysis identifies five sub-basins in the region. Shannon’s entropy information theory has been performed to compute the water quality index (WQI) without having any subjective bias in the analysis. The analysis of the WQI shows that sub-basin 2 (WQI = 38.35) has excellent quality of groundwater, whereas sub-basin 1 (WQI = 52.43), 3 (WQI = 63.94), and 5 (WQI = 82.79) are having good groundwater quality. On the other hand, sub-basin 4 (WQI = 102.99), which covers mostly the central part of the main stream, is found to be most contaminated and having a medium quality of the groundwater. Analysis of the groundwater parameters using the PCA indicates that the quality of groundwater in the study area is controlled mainly by three main factors, which are geogenic process (weathering and leaching of rocks), seawater intrusion (natural process), and anthropogenic activities. Furthermore, hydrometeorological analysis shows a gradual drop in precipitation, water level depth, and the percolation index (PI). This indicates an over exploitation of groundwater resources in the study region under the present circumstances of climate variability, population and industrialization.The results obtained in this paper are useful for identifying suitable sites for tube-wells and bore-wells for drinking and agricultural purposes, and also for developing an effective strategy to avoid further contamination of groundwater aquifers in the region. Results are extremely useful for government agencies and policymakers in achieving the United Nations (SDG-6) goals of suitable planning and sustainable development of groundwater resources by 2030.

Active tectonics in the Moulay Idriss Massif (South Rifian Ridges, NW Morocco): New insights from geomorphic indices and drainage pattern analysis

The Moulay Idriss Ramp anticlines of the South Rifian Ridges are located in the front of the Moroccan Rif Belt (southern branch of the Arc of Gibraltar) and have accommodated the tectonic escape of this Alpine chain as an active edge, in response to the converging Eurasian and African plates. Nevertheless, recent evidences of this landscape tectonic activity remain poorly defined. We investigated the variations in tectonic activity and evaluated its influence on the landscape evolution, through the application of geomorphic indices including: the mountain front sinuosity, valley floor width-to-height ratio, drainage basin asymmetry factor, hypsometric curves, normalized steepness index, longitudinal river profile, and χ as an indicator of drainage network disequilibrium. Morphotectonic study shows that fault related folds, in the area, produce differential uplift with a relatively high degree of tectonic activity along the eastern part of the massif. The doming process accounts for the elevation of the area, in the Dehar en Nsour salt dome, and this in turn, could be explained as being promoted by the Nzala des Oudayas fault system. On the other hand, the Moulay Idriss fault exerts a strong influence on the morphology of the Fert El Bir anticline inducing the Khoumane river deflection, while other streams exhibit rejuvenation and water divide migration. These new data elucidate the recent tectonic evolution of folds and strike-slip fault systems in the southern front of the Gibraltar-Rif southern edge, which contributes to the movement of the Rif belt with respect of the stable Africa, and sheds new light on the ‘‘Meknes’’ earthquake, confused with the contemporaneous 1755 Lisbon earthquake.

River redirected

Glaciers and ice sheets are retreating in response to climate warming. An analysis of drainage patterns of a huge glacier in Yukon, Canada shows that glacier retreat has led to a drastic change in the destination of its meltwater in spring 2016.

Morphotectonics of the Jamini River basin, Bundelkhand Craton, Central India; using remote sensing and GIS technique

Morphological and morphotectonic analyses have been used to obtain information that influence hydrographic basins, predominantly these are modifications of tectonic elements and the quantitative description of landforms. Discrimination of morphotectonic indices of active tectonics of the Jamini river basin consists the analyses of asymmetry factor, ruggedness number, basin relief, gradient, basin elongation ratio, drainage density analysis, and drainage pattern analysis, which have been completed for each drainage basin using remote sensing and GIS techniques. The Jamini river is one of the major tributaries of the Betwa river in central India. The Jamini river basin is divided into five subwatersheds viz. Jamrar, Onri, Sainam, Shahzad and Baragl subwatershed. The quantitative approach of watershed development of the Jamini river basin, and its four sixth (SW1-SW4) and one fifth (SW5) order subwatersheds, was carried out using Survey of India toposheets (parts of 54I, 54K, 54L, 54O, and 54P), Landsat 7 ETM+, ASTER (GDEM) data, and field data. The Jamini river has low bifurcation index which is a positive marker of tectonic imprint on the hydrographic network. The analyses show that the geomorphological progression of the study area was robustly influenced by tectonics. The analysis demonstrates to extensional tectonics system with the following alignments: NE–SW, NW–SE, NNE–SSW, ENE–WSW, E–W, and N–S. Three major trends are followed by lower order streams viz. NE–SW, NW–SE, and E–W directions which advocate that these tectonic trends were active at least up to the Late Pleistocene. The assessment of morphotectonic indices may be used to evaluate the control of active faults on the hydrographic system. The analysis points out westward tilting of the drainage basins with strong asymmetry in some reaches, marked elongation ratio of subwatersheds, and lower order streams having close alignment with lineaments (active faults). The study facilitated to considerate the function of active tectonism in the advancement of the basin.

Hydro-Morphometric characterization of Wadi Khumal Basin, Western Coast of Saudi Arabia

The aim of this study is to assess the hydro-morphometric and flow characteristics (include: morphology, analysis of drainage patterns, and drainage morphometry) and its influence on hydrology of Wadi Khumal Basin, North Saudi Arabia, which is considered as an additional strategic future water supply for ground water reservoirs and for planning rainwater harvesting and watershed management. For detailed study we used Shuttle Radar Topographic Mission (SRTM) data for preparing Digital Elevation Model (DEM), aspect grid and slope maps, Geographical information system (GIS) was used in evaluation of linear, areal and relief aspects of morphornetric parameters. The study reveals that the triangular shape of the Wadi Khumal Basin is mainly due to the guiding effect of Scarp-Radwa Mountains and to many of the thrusts, faults and dykes that appear in hard and massive metamorphic and igneous rocks which resists weathering processes to give that shape. Study adopted in hydrological analysis of the Khumal Basin on the model TR-55 to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater reservoirs, where a rainstorm were analyzed its 25 mm, Runoff hydrographs were constructed for four sub-basins of wadi Khumal.

Morphometric analysis of a highland microwatershed in East Khasi Hills District of Meghalaya, India: Using remote sensing and geographic information system (GIS) techniques

Morphometric analysis of a highland microwatershed (Wah Umbah) area was carried out using remote sensing and geographic information system (GIS) techniques. Detailed drainage map of the area was prepared from the high resolution satellite image and Survey of India (SOI) toposheets which was updated using IRS-1D PAN sharpened LISS-III analog data. Updated drainage maps were used for the drainage pattern analysis of the study area, The Wah Umbah microwatershed shows a sub-trellis drainage pattern with moderate drainage texture. High bifurcation ratio indicates a strong structural control on the drainage pattern. Lithological, structural and gemorphological expression of the microwatershed control the flow direction of the entire drainage network. It has been noticed that Wah Shella microwatershed is under the category of creep or tilting and hence it is vulnerable to geohazard. Key words: Morphometry, Wah Umbah, microwatershed, drainage, geographic information system (GIS), remote sensing, hydrological.

Active tectonics of NE Gujarat (India) by morphometric and morphostructural studies of Vatrak River basin

Landscape owes its shape to the combination of tectonic and climatic forces. Differential displacement of land by tectonic processes changes the elevation of earth’s surface locally and in turn affects the rate of geomorphic processes which are altitude dependent. The tectonic and geomorphic processes are very tightly coupled and their results are intertwined. To extract the tectonic signal, the numerical modelling of the landscape of the Vatrak River basin, part of which falls in the northern part of the Gujarat Alluvial Plains of western India, has been undertaken applying morphometric and morphostructural approach. The study helped in understanding the role of tectonic elements in the evolution of the basin. Demarcation of geomorphic indicators of active tectonics (which include the analyses of asymmetry factor, valley floor ratio, gradient, basin elongation ratio, long profile and related parameters, pseudo hypsometric integral, drainage basin asymmetry), drainage pattern analysis and azimuthal distribution of stream channels have been performed for each drainage network and associated basin. The morphological field evidence of tectonics combined with the results of morphometric analysis has been used to obtain information about the orientation of tectonic elements and the possible reconstruction of their activity in recent times. The analyses indicate eastward tilting of the drainage systems, strong asymmetry in some reaches, pronounced elongation of certain tributaries, long profiles indicating base level lowering, poor organisation of the hydrographic network, and close alignment between lower order streams and active faults. All these analyses point towards the active tectonism in the area. Data obtained through the statistical analysis of preferred stream orientations confirm that the old tectonic directions markedly influenced the drainage network development of the older order streams, whereas, streams of lower order which preferentially follow the N–S and NE–SW directions suggest that these tectonic trends were active until very recent times.

Active tectonics in the Sierra Nevada (Betic Cordillera, SE Spain): Insights from geomorphic indexes and drainage pattern analysis

The Sierra Nevada of the central Betic Cordillera is a 3000 m-high mountain range surrounded by Neogene–Quaternary sedimentary basins, having been uplifted since Late Miocene times. The southern and western mountain fronts of the Sierra Nevada are fault-bounded, while the northern one is an unconformity between the Neogene–Quaternary sediments of the Guadix–Baza basin and the metamorphic rocks of the Nevado–Filabride complex. We have carried out a geomorphic study by examining drainage patterns and characteristics of mountain fronts in order to reveal areal variations and styles of rock uplift. Mountain front sinuosity ( S mf), area–altitude relations (hypsometric curves), and valley floor entrenchment differ significantly between the northern, western, and southern mountain fronts. The lack of important faults along the northern Sierra Nevada mountain front, together with the elevated topographic position of the Guadix–Baza basin (average altitude is around 1100 m), points to similar uplift of both geomorphic units (sierra and basin) in a single large-scale crustal block. The asymmetry factors show systematic asymmetries at both sides of the Lanjarón River, probably due to the presence of an active NNE–SSW oriented antiform in the western Sierra Nevada. Finally, river profiles indicate maximal river entrenchment in the western part of the Sierra Nevada, probably related to the uplift of the footwall of the Padul–Nigüelas fault-system. Therefore, our geomorphic analysis suggests that the western part of the Sierra Nevada is tectonically active by means of a combination of normal faults along the mountain front and NNE–SSW oriented active folds, which, in turn, likely have a gravitational origin related to the exhumation of the footwall of the normal fault-system.

Active deformation front delineated by drainage pattern analysis and vertical movement rates, southwestern Coastal Plain of Taiwan

Orogenesis in Taiwan results from an arc-continent collision between the Eurasian plate and the Philippine Sea plate. The southwestern part of Taiwan absorbs active shortening as evidenced by rapid crustal deformation and frequent earthquakes. Southwestern Taiwan may be subdivided into three tectonic–geomorphic domains, including the plain (PL), the tilted tableland (TT), and the low hills (LH), based on geomorphology, drainage pattern and stratigraphic records. The PL domain is the westernmost and is characterized by meandering rivers with relatively low surface slope and river gradient, but high river sinuosity. The TT domain has slightly tilted terraces with river meanders and many tributaries are developed on its surface. Anomalous river sinuosity occurs as a result of active tectonics. The LH domain has higher elevation and deformed geomorphic surfaces associated with a dissected landscape. This domain also has high stream gradients with low sinuosity which may indicate active deformation. We define crustal deformation, using Holocene deposits and radiocarbon dating in addition to geomorphic analysis that suggests a blind thrust may exist between the PL and TT domains. This blind thrust may indicate the position of the active deformation front of the orogenic belt of southwest Taiwan.

The influence of geological fabric and scale on drainage pattern analysis in a catchment of metamorphic terrain: Laceys Creek, southeast Queensland, Australia

The relationship between geological fabric and drainage patterns in the 81.8 km 2 Laceys Creek sub-catchment of the North Pine River catchment, southeast Queensland, Australia, is analysed using a new channel–ordination system. The Laceys Creek catchment is situated on the South D'Aguilar Block, which underwent metamorphism, faulting and uplift from the Late Carboniferous to Late Triassic. The catchment drains exposures of two main rock units, the Neranleigh–Fernvale Beds and the Bunya Phyllite. Both units are composed of metamorphosed deep-sea sediments that accumulated as an accretionary wedge during late Palaeozoic subduction of the palaeo-Pacific plate under the eastern margin of the Australian craton. The new channel ordination system used in this study allows improved classification of stream segments of equal prominence or rank in comparison to previous schemes. A 10 m contour digital elevation model (DEM) was produced within which drainage channels were digitised. Planar geological features, including bedding, faults, joints and cleavage, were mapped in the field and collated with data from previous geological mapping programs. Regional and local trends of geological fabric are reflected in the variable orientation of channels of different rank in the catchment. Cleavage and fractures are the dominant planar features of the Bunya Phyllite and these correlate most closely with the orientation of middle-order incised stream segments. In contrast, middle-order channels on the Neranleigh–Fernvale Beds most closely correlate with bedding, which dominates the fabric of this unit. Although anthropogenic factors exert local influence and climatic processes exert broad influence on the catchment, this study focuses on structural and lithological fabrics, which are the apparent dominant controls on middle-order channel orientations. Identification of congruent patterns between bedrock fabric and channel ranks is variable, depending on the scale and number of channels included in the analysis. Many low-rank channels correspond closely to the orientation of fine-scale bedding and foliation and these influences may not be detected by coarse-scale mapping. Understanding the extent of geological controls on the morphology of a catchment may assist geo-hazard identification, land-use planning and civil-engineering projects.

Investigation of active faults in Morocco using morphometric methods and drainage pattern analysis

A survey has been done of recently active faults in Morocco. In addition to field observations, morphometric methods were applied and an analysis was made of the drainage pattern. In the morphometric analysis, a map of vertical deformation was established from the elevations of summit level surfaces. This enables the recognition of neotectonic discontinuities and lithological contrasts; the actual discrimination of different rock-types can only be achieved by comparison with field observations. The analysis of drainage patterns — including their perturbations and anomalies — can also reveal the presence of features due to neotectonics, structural control or lithological variation. Certain faults can be detected which correspond to structures known from field geology or remote sensing (NE-SW and NW-SE oriented sets). Some new faults are observed which belong to these sets, as well as others which define a new N-S trending set. The present analysis leads to a distinction between ancient faults and currently active faults. The results of this study are shown on a map of recently active faults where the respective vertical displacements are also indicated.

A study of joints and stress-release buckles in Palaeozoic rocks of the Niagara Peninsula, southern Ontario

Joint sets in Palaeozoic bedrock of the Niagara Peninsula occur at 005, 045, 085, and 135° orientations. There is no consistent change in joint orientation with lithology, rock age, or location within the area. Drainage pattern analysis using airphotos and topographic maps indicates that glacial drift effectively masks underlying joint systems. Rare calcite and gypsum mineralization occurs along joints of 085 and 135° trend. Stress-relief buckles indicate a contemporary maximum principal stress along an 050° trend. Joint systems in the Niagara Peninsula are similar in trend to those on the Appalachian Plateau.

Exploratory Techniques Along Markley Gorge, Sacramento Valley, California: ABSTRACT

The Markley gorge channel, an ancestral Sacramento river channel, is in the central part of the Sacramento Valley of California. This fossil channel was cut subaerially during late Eocene time and filled in a marine to marginal marine environment during late Eocene and Oligocene times. Before the late Eocene transgression, an early mature stage of stream erosion was reached. Terraces, islands, meanders, and tributaries can be delineated by subsurface methods. The slope along the channel banks ranges from 6 to 36°. Variations of the slope along the channel banks depend on the existing faults, structures, and drainage configuration. Because the gorge fill is unconformably overlain by Miocene continental sediments, the original relief is not known, but it at least excee s 3,000 ft. This channel has been traced in the subsurface more than 80 mi and has a maximum width of 10 mi. The north end of the gorge is the Wheatland Formation cropping out at the foot of the Sierra Nevada Mountains near the town of Marysville. The south end of the gorge is in the Montezuma basin where gorge sediments merge with deeper water sediments of the Sidney Shale and shallower water sediments of the Kirker Formation. The gorge fill consists predominately of shale with minor amounts of sandstone and conglomerate which have considerable lateral and vertical lithologic variation. Truncation of the underlying Eocene, Paleocene, and Upper Cretaceous formations by the Markley gorge combine with local structure to form commercial gas accumulations. Examples are: Maine Prairie (75 Tcf, 1,020 BTU); Liberty Island (24 Tcf, 988-996 BTU); Millar (18 Tcf, 980 BTU); Todhunters Lake (57 Tcf, 890-897 BTU); and Greens Lake (8 Tcf, 830-850 BTU). Along the north part of the Markley gorge, in the proximity of the city of Sacramento, gas traps exist in westerly dipping Upper Cretaceous sandstone reservoirs. These reservoirs occur in reentrants and islands within the predominantly shale-filled gorge. These spurlike reentrants were created by easterly trending tributaries which intersected the main southerly trending Markley channel. Techniques in locating Upper Cretaceous reentrants and islands are well control, drainage pattern analysis, gravity profiling and mapping, seismic profiling and mapping, and differential compaction features. An understanding of the geologic history of the gorge and of the truncated sediments is also necessary to locating potential future gas fields along the gorge. End_of_Article - Last_Page 439------------

Comparison of Types of Imagery for Photogeomorphic Studies: ABSTRACT

This discussion is limited strictly to photogeomorphic, End_Page 635------------------------------ not bedrock mapping, applications of airborne imagery. Two factors control the value of a particular image in a particular study--scale and type of imagery. Small scale imagery, less than 1:40,000, is particularly useful in broad, regional studies of structural trends, regional drainage pattern analysis, and lineament mapping. The larger scale imagery is more useful in fracture trace studies, local drainage pattern and single channel feature studies, and local tonal anomaly studies. Large-scale imagery may, of course, be compiled into a mosaic. A wide variety of image types are available today. The most commonly available are black and white photography with many possible filter combinations, black and white infrared photography, color and color infrared (false color) photography, and thermal infrared and radar imagery. These images have a large range in cost and applicability. As a tool of the photogeomorphologist, color aerial photography appears to be the most generally useful for a basic study. Black and white, and black and white infrared, photography are the least expensive and quite useful. The other types of imagery have special, and sometimes very useful, applications. Of value in some cases is sequential imagery showing, for example, variations of vegetation throughout the year. Such time-dependent changes in terrestrial features may have significance in photogeomorphic exploration. End_of_Article - Last_Page 636------------

Geomorphology along the Ichihazama and the Nihazama Rivers

The Ichihazama and the Nihazama rivers originate in the back-bone range of Tohoku, run through hilly area of Pleistocene Pyroclastic-flow deposits, and reach the Snauma lowland in the northern part of the Sendai plain.The results of the author's study on the river terraces and hills along these rivers arc as follows;1) The geomorphological surfaces are classified as in Fig. 1, and the relation between terraces and the lacustrine deposits is shown in Figs. 8, 9 and 10.2) The western part of the hills is composed of dacite and tuff of Pleistocene (Kitamura 1956) and the hilltops in the eastern part of it are covered comformably with gravel bed (Hanzawa, Kitamura 1957). Fujiwara (1958) suggested that the hill surface is subdivided into two levels covered with different gravel layers without detailed description and mapping.The present author has acertained that the eastern part of the hills consists of the remnant surface of terraces in two levels: the upper one 70 to 90m, and the lower 40 to 50m above sea level. The upper covers comformably the pumiceous tuff in the lower half of the middle reaches as was reported by Hanzawa and Kitamura (1957) and others, while in the upper half the surface of pumiceous tuff is terraced and the older alluvium underlies a lower level terrace surface in dendritic pattern. The longitudinal pattern of the older alluvium is shown schematically in Fig. 7. The levels of deposition and erosion on these two, therefore, are about 70m and 50m above sea level.3) The upper Tsukidate surface is distributed widely in the middle reaches. The surface was reported hitherto as that of fluvial origin, however it is fill terrace formed at the time of the high sea level at the hieght less than 20m above sea level. Fujiwara (1958) suggested an uplift of the surface near Tsukidate by means of drainage pattern analysis. The author presumes that the terrace-building was influenced by a regression of sea, and in the development there may have been a tectonic movement.4) Oide (1964) reported that certain deposits upvalley a gorge in the upper reaches of the Ichihazama river is lacustrine deposits lain in a lake basin produced by an uplfit of gorges of Miocene andesite. In his opinion the barrier is shown with the site of present gorges. Imaizumi (1966) supported his opinion. The present author thinks that the lacustrine deposits was lain through violent accumulation of voluminous sandy tuff in a short time, for the deposit scarcely shows lamination and has nodules, erected stumps and pisolite particles in non-stratified material. The heavy-mineral analysis reveals that the lacustrine deposits are same as the Kitagawa formation (dacite and its tuff) and the uppermost volcanic ash on the terrace and hill surfaces along the Eai river.5) The gentle slopes of erosion cut terraces under-lain with so-called lacustrine deposits in the upper reaches of the Ichihazama river. Some of their lower flanks may have been buried beneath the alluvial plain surface in the middle reaches. Drift wood in the so-called lacustrine deposits was dated 27, 000±1, 700yrs B. P. by C-14 method (Oide 1964). Its form is very much akin to cryopediment (Wako 1960).

Geomorphic Expression of Selected Concealed Structures in Western Canada: ABSTRACT

Analysis of drainage patterns can be used to delineate concealed structures. To do this effectively, a thorough understanding of the regional geology and general geomorphic history is necessary. In glaciated areas, air photographs and mosaics can be used to determine the general glacial history so that glacially controlled patterns are not confused with structurally controlled patterns. As with any unconventional technique, drainage pattern interpretation has been misunderstood, misused, and handicapped by the lack of a generally acceptable theory to explain the reflection of buried structures in surface stream patterns. Geomorphic analyses are used in both regional and detailed studies. Regionally, the area between Fort St. John and Fort Nelson in northeastern British Columbia exhibited a pre-Pleistocene trellis drainage pattern, adjusted to structural conditions. Glaciation altered the existing base-level equilibrium. After the ice melted, large-scale stream piracy took place. Due to glaciation and subsequent piracy, non-structurally controlled End_Page 420------------------------------ anomalous drainage patterns exist which must not be confused with structurally controlled patterns. The West Drumheller, Drumheller, Homeglen-Rimbey, and Redwater Devonian reef oil fields, all located in Alberta, were studied in detail. The drainage configuration above the West Drumheller oil field consists of a pronounced arc in the otherwise straight southeasterly course of the Red Deer River, and a repeated right-angular diversion of a tributary. The Drumheller oil field is reflected by a marked diversion and arcuate pattern of Michichi creek. The Homeglen-Rimbey oil field is in the Blindman River system in which the tributaries flow southeasterly. At the oil field all streams are diverted toward the west, resuming the southeasterly flow at the south end of the field. These three drainage anomalies are not related to glacial landforms. Finally, the Redwater oil field is an exampl of a structurally controlled drainage anomaly which has been partly masked by a complex glacial history. Other oil fields exist which are not reflected in the drainage pattern. This does not weaken the technique of drainage analysis, but indicates that in the present state of knowledge not all possible types of drainage anomalies can be recognized. It is only through continued use and research that this technique, proved to be a fast and economical exploration tool in mantled areas, can be refined. End_of_Article - Last_Page 421------------

THE VALUE OF AIR PHOTOGRAPHS IN THE ANALYSIS OF DRAINAGE PATTERNS

ABSTRACTThe object of this paper is to provoke discussion and not to present a finished study. It deals briefly with quantitative analysis of drainage patterns in geomorphological studies and refers to methods that have recently received some attention in the United States. It points to the value of aerial photographs in such studies and asks for discussion of two important points: firstly, whether the mathematical approach is soundly based; and, secondly, whether the analytical method is likely to give useful practical results.