BEBERAPA PENGERTIAN DASAR

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BEBERAPA

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I. Geomorphology

is the study of landforms

(Lobeck, 1939)

II. Geomorphology

is the science of landforms

(Thornbury, 1954)

III. Geomorphology

is the study which describes landforms and the process which their

formation, and investigates the interrelationship, of these forms and

process and their special arragement

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F f P M dt : : : : : Landform (bentuklahan) Fungsi dari Proses Material

Perubahan menurut waktu

IV. Geomorphology

• Studi mengenai bentuk bumi (Derbyshire, 1979, p. 15)

• Studi tentang bentuk lahan (landform)

Lingkup studi

• Derbyshire, 1979, p. 17

F = f(P,M) dt

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Derbyshire membedakan 4 level dari studi geomorfologi

Level 1 : study of elements of the equation

(studi tentang bentuklahan, proses, dan material, masing-masing

secara terpisah)

Level 2 : Balancing the equation

Mencari hubungan timbal balik antara bentuklahan, proses, dan

material pada suatu daerah tertentu pada saat tertentu pula

Level 3 : Differenciating the equation

Termasuk dalam hal ini pengujian cara-cara mengetahui hubungan

timbal balik antara ketiga elemen tersebut dan variasinya menurut

waktu

Level 4 : Applying the equation

Penggunaan manfaat dari ketiga level tsb di atas untuk maksud

pengelolaaan lingkungan

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V. Geomorphology

is the study of landforms, and in particular of their nature,

origin, processes of development, and material

composition.

(Cooke, et. al., 1974)

VI. Geomorphology

Dalam lingkup studi geomorofologi tercakup:

• Bentuk lahan (landform)

• Proses-proses geomorfologi

• Genesis (asal-usul/perkembangan jangka panjang)

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VII. Geomorphology

is the scientific study of landscapes and the processes that

shape them. The science of geomorphology has two major

goals.

1. One is to organize and systematize the description of

landscapes by intellectually acceptable schemes of

classification.

2. The other is to recognize in landscapes evidence for

changes in the processes that are shaping them and

have shaped them (Arthur Bloom)

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Karmono Mangunsukardjo (1986) menjabarkan 4 aspek geomorfologi :

1. Studi mengenai bentuklahan, atau disebut dengan morfologi,

mempelajari relief secara umum yang meliputi aspek :

a). Morfologi

Yakni aspek-aspek yang bersifat pemerian suatu daerah, antara

lain teras sugai, beting pantai, kipas aluvial dan plato

b). Morfometri

Yakni aspek-aspek kuantitatif dari suatu daerah seperti

kemiringan lereng, bentuk lereng, ketinggian, beda tinggi,

kekerasan medan, bentuk lembah, tingkat pengikisan dan pola

aliran

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2. Studi mengenai proses geomorfologi,

Yakni proses yang mengakibatkan perubahan bentuklahan dalam

waktu pendek serta proses terjadinya bentuklahan yang mencakup

morfogenesa, dengan aspek-aspek :

a). Morfo-struktur pasif

meliputi litologi (tipe dan struktur batuan) yang

berhubungan dengan pelapukan

b). Morfo-struktur aktif

berupa tenaga endogen

c). Morfo-dinamik

berupa tenaga eksogen yang berhungan dengan tenaga

angin, air, es, gerak masa batuan dan volkanisme

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3. Studi geomorfologi yang menekankan pada evolusi pertumbuhan

bentuklahan atau morfo-kronologi, menentukan dan memerikan

bentuklahan dan proses yang mempengaruhinya dari segi umur relatif

dan umur mutlak

4. Geomorfologi yang mempelajari hubungannya dengan lingkungan,

studi ini mempelajari hubungan antara bentuklahan dengan

unsur-unsur bentangalam seperti batuan, struktur geologi, tanah, air,

vegetasi dan penggunaan lahan

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Geomorphology should not be viewed as a product of lithosphere

processes but as part of an integrated earth-surface system of

interacting "sphere": lithosphere, hydorsphere, atmosphere, and

biosphere. Geomorphology is an environmental science as much

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Landform (bentuklahan)

Bentukan alam di permukaan bumi yang terjadi karena proses pembentukan tertentu dan melalui serangkaian evolusi tertentu pula.

atau

Bagian dari permukaan bumi yang mempunyai bentuk khas sebagai akibat pengaruh dari proses, struktur geologi, dan batuan selama periode waktu tertentu. Oleh karena itu bentuklahan ditentukan oleh faktor-faktor topografi, struktur geologi, batuan, dan proses eksogen.

atau

merupakan bentangan permukaan lahan yang mempunyai relief khas karena pengaruh kuat dari struktur kulit bumi dan akbibat dari proses alam yang bekerja pada batuan di dalam ruang dan waktu tertentu. Masing-masing bentuklahan dicirikan oleh adanya perbedaan dalam hal struktur dan proses geomorfologi, relief/topografi dan material penyusun/litologi (Strahler, 1983 dan Whiton, 1984).

Misal :

Teras sungai : proses sedimentasi oleh aktivitas sungai dan berkembang sampai terbentuknya (evolusi)

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Landscape (bentanglahan)

Panorama atas suatu hamparan daratan yang terdiri dari berbagai keadaan alam baik alami maupun buatan manusia (artifisial).

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Topografi

Menyatakan ketinggian tempat di permukaan bumi dengan ukuran

satuan ketinggian tertentu

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Terrain

Merupakan istilah yang diperuntukkan guna menyatakan keadaan medan suatu wilayah di permukaan bumi, baik keadaan reliefnya, vegetasi/

penggunaan lahan, adanya sungai-sungai, rawa-rawa, sifat-sifat umum batuan dan lahan, dll.

Istilah ini digunakan terutama untuk keperluan militer (PD I, II)

The collection, analysis, evaluation, and interpretation of geographic information on the natural and manmade features of the terrain, combined with other relevant factors, to predict the effect of the terrain on military operations. Military Dictionary (DOD, NATO)

Digital Geomorphometry based on the use of DEMs is nowadays covered by the concept of terrain analysis (Wilson dan Gallant, 2000)

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Digital Terrain Analysis

The use ofremote sensing satellite data for mapping various aspects of terrain, such as land cover, land use, and soils. Software may then be utilized to derive terrain parameters, such as aspect, catchment area, and wetness index, which are then used to describe the morphology of the landscape and the influence of topography on environmental processes.

C:/Sleman/3_D/m obil_3D.sxd

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Imagery

Digital

Terrain Data

(DEM)

3D

Digital Model

D:/Military/

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Morphometric parameters

• elevation change gradients (slope)

• orientation gradients (aspect, steepest downhill slope, viewshed) • curvature gradients (horizontal or tangent curvature)

• vertical or profile curvature (mean curvature • combined gradients (tangential curvature).

3D Analyst

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Generic landforms

– Stream channel (Valley bottom) - Locations of water accumulation and transition; high number of upstream elements and concave shapes.

– Ridge (Peak) - Locations of water run-off; lowest upstream contributing area and convex shapes. – Slope - Sloping part with generally higher shape complexity.

– Plain (Terrace) - Flat areas of low relief and low shape complexity. – Pit - Conical concave landform.

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Topographic attributes: elevation (meters), slope (degree) aspect (degree), planform curvature, topographic wetness and stream power

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Topographic wetness

and stream power indices were used to quantify flow

intensity and accumulation potential. Topographic wetness (also known as Compound Topographic Index [CTI] or topographic moisture index) at a particular point on the

landscape is the ratio between the catchment area contributing to that point and the slope at that point (Wilson and Gallant, 2000). Higher positive values are wetter and lower

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The Stream Power Index (SPI) is closely related to the topographic wetness index and is used to estimate the erosive power of the terrain. Areas with large stream power indices have a great potential for erosion. If total stream power is greater than that required to transport the sediment available (supply limited), then there will be a net loss in sediment and the stream will erode. If stream power is less (transport limited) than that required, then there will be a net gain in sediment and the stream will aggrade. Values are calculated as:

Stream power index = Catchment areaxtan β (Moore et al., 1993)

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GIS-Based Automated Landform Classification and Topographic, Landcover and Geologic Attributes of Landforms Around the Yazoren Polje, Turkey

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Perencanaan dan Operasi Militer

Pemahaman karakteristik medan menentukan akses yang efektif

Drop Zone 1

Drop Zone 2 Target Objective

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a. Relief

Bentuk wilayah : keadaan tinggi rendah suatu wilayah di permukaan

bumi ditinjau dari segi perbedaan tinggi dan kemiringannya (lereng)

atau

Bentuk ketidakteraturan secara vertikal, baik dalam ukuran besar

maupun kecil dari permukaan litosfer.

Misal :

datar, landai , berombak, bergelombang, berbukit kubah

(humocky), berbukit, bergunung.

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HUBUNGAN RELIEF LERENG DAN BEDA TINGGI (US Soil Survey)

Relief Lereng (%) Beda tinggi (m)

Datar/hampir datar 0-2 <5 Berombak/Topografi landai 3-7 5-50 Berombak-bergelombang, topografi miring 8-13 25-75 Bergelombang-berbukit, topografi dengan lereng sedang

14-20 50-200

Perbukitan/topografi terjal 21-55 200-500

Pegunungan/topografi sangat terjal 56-140 500-1000

Pegunungan sangat curam >140 >1000

RELIEF :

1. datar (D) 2. landai (L) 3. berombak (B)

4. bergelombang (Gb)

5. berbukit kubah (humocky)/Bk 6. berbukit (Bt)

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HUBUNGAN RELIEF LERENG DAN BEDA TINGGI (Sunardi J., 1985)

Relief Lereng (%) Beda tinggi (m)

Datar 0-3 <5

Landai/berombak 5-8 5-10

Landai/Miring 8-15 10-25

Miring/berbukit 15-25 25-100

Miring terjal/ berbukit terjal 25-45 100-200

Terjal (berbukit terjal) 45-100 200-500

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Panjang LERENG (US Soil Survey)

Panjang Lereng (m) Keterangan

0 - 15 Sangat pendek

25 - 50 Pendek

50 - 250 Panjang menengah

250 - 500 Panjang

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Landforms evolve through the slow erosional removal of weaker rock, leaving the more resistant rock standing as ridges or mountains. (Drawn by A. N. Strahler.)

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Komponen dari relief yaitu :

a. amplitude (beda tingggi antara lembah dan puncak)

b. bentuk punggung

c. bentuk lereng

d. bentuk lembah

Aspek relief yang lain :

1. hubungan antara unit reliief kemiringan lereng dan

perbedaan tinggi relief

2. kepadatan aliran

3. pola aliran sungai

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The concept of slope gradient. (a) How slope is measured on the landscape and the two ways in which it can be expressed (degrees and percent). (b) Limits and deﬁnitions of slope classes used by the Natural Resources Conservation Service. Map units with complex slopes require the use of more than one term, e.g., “steep and moderately steep.” The overlap of ranges allows them to be speciﬁcally set for each survey area. After the Soil Survey Division Staff (1993).

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Geomorphic components of slopes in a landscape with an open drainage system. After Ruhe (1975b).

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Examples of Simple (S), Compound (C), Complex (Cx) hillslope proﬁles, slope breaks (Br), as viewed in cross-section. After Ahnert (1970).

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The nine basic geometric forms of hillslopes, with ﬂowlines illustrating

how water and debris (theoretically) moves on

them.

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Pediment adalah lapisan tanah dasar / batuan dasar yang sangat landai (kemiringan sekitar 5°).

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• Morfologi Positif:

– Gunung (Mountain)

– Bukit (Hill)

– Kubah (Dome)

– Punggungan (Ridge)

• Morfologi Negatif

– Lembah (Valley)

– Cekungan (Basin)

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Komponen dari relief yaitu :

a. amplitude (beda tingggi antara lembah dan puncak)

b. bentuk punggung

c. bentuk lereng

d. bentuk lembah

Aspek relief yang lain :

1. hubungan antara unit reliief kemiringan lereng dan

perbedaan tinggi relief

2. kepadatan aliran

3. pola aliran sungai

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http://www.sciencedirect.com/science/article/pii/S0016706110003976

: Mountains : Alluvial fans : Valleys

: Wash drainage areas

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Pola aliran merupakan cerminan dari struktur dan tipe/ komposisi

batuan. Sedangkan kerapatan aliran mencerminkan

resistensi

dan

kekedapan batuan

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Studi tentang drainase pada foto udara atau data PJ meliputi 3

aspek :

1. tekstur drainase (drainage texture) atau kerapatan aliran

2. bentuk lembah (valley shape)

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tekstur drainase merupakan kerapatan drainase (rasio

total panjang sungai dalam sebuah DAS) dan frekuensi

drainase (jumlah aliran sungai dalam DAS dibagi

dengan luas DAS).

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Tekstur drainase atau Kerapatan Aliran terutama dipengaruhi oleh tiga

faktor :

a) Iklim,

b) Relief

c) Karakter dari batuan dasar atau tanah (yaitu porositas dan

permeabilitas).

Kerapatan aliran dapat dideskripsikan sebagai:

• sangat halus (ultra fine),

• halus (fine),

• sedang (medium),

• kasar (coarse)

Kerapatan aliran mencerminkan resistensi dan kekedapan batuan.

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 Batuan kompak dan permeabel

 Batuan lunak dan impermeabel

 Kerapatan aliran jarang

 Kerapatan aliran rapat

Kerapatan aliran

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Drainage density

Texture DD (km/km sq.) Conditions

Coarse (low) <8 • Permeable or resistant

• Humid and well vegetated

Medium 8-20 • Permeable rksh. • Rainfall • well vegetated Fine (high) 20-200 • Impermeable surface • Low rainfall • Little vegetation Ultra fine >200 • Impermeable surface • Low rainfall

• easily erodible rocks • little vegetation

The interpretation of DD varies with map scale. Typically its measured on a scale of 1:24,000.

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C = clayshale

SC = sandy or silty clay

Ss = sand or sandstone

Texture Common

Coarse gravel(ly)

Medium sand(y)

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Drainase dikatakan internal ketika beberapa garis drainase terlihat di

permukaan dan sebagian besar di bawah permukaan (sub-surface),

misalnya batugamping (limestone) dan kerikil (gravel).

Drainase eksternal di mana jaringan drainase terlihat baik di permukaan.

Kerapatan drainase rendah pada batuan permeabel, seperti: tanah liat

(clays), serpih (shales).

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argillaceous = “berlempung”

untuk menentukan batu di mana mineral lempung merupakan komponen sekunder tapi signifikan. Misalnya, batugamping berlempung (argillaceous limestones ) adalah batugamping yang terdiri sebagian besar dari kalsium karbonat, tetapi termasuk 10-40% dari mineral lempung: batugamping tersebut, ketika lembut, sering disebut napal. Demikian pula, argillaceous

sandstones (batupasir berlempung) adalah batupasir yang terutama terdiri

dari biji-bijian kuarsa, dengan ruang interstitial penuh dengan mineral lempung.

Calcareous = “berkapur”

Berkapur adalah kata sifat yang berarti sebagian besar atau sebagian terdiri dari kalsium karbonat, dengan kata lain, mengandung kapur atau menjadi kapur.

Arenaceous = “berpasir”

batuan klastik sedimen dengan ukuran butir pasir antara 0,0625 mm

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Bentuk lembah dapat bervariasi terkait dengan batuan dasar atau tanah.

• Bentuk V sering berkembang di pasir (sands) dan kerikil (gravels),

• Bentuk U berkembang di tanah lanau (silty soils).

• Bentuk lembah yang panjang dengan penampang membulat

menunjukkan tanah lempung (clayey soils) .

2. Bentuk lembah (valley shape)

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3. Pola drainase (Drainage pattern)

adalah “spatial arrangement” dari sungai (streams).

 Batuan miring

 Batuan yang landai dan homogen

 Batuan dengan struktur kekar dan sesar intensif

 Struktur lipatan

 pola aliran pararel

 pola aliran dendritik

 pola aliran rektanguler

 pola aliran trellis

Pola aliran merupakan cerminan dari struktur dan tipe/ komposisi

batuan.

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DENDRITIC • Tree • Uniform Rock TRELLIS • Alternating layers of hard and soft rock

• Parallel

streams

RADIAL

• From highest central

point (butte/conical hill)

RECTANGULER

• Bends 90o

• Tributaries 90o

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Dendritic drainage pattern.-_{Also called trees like or arborescent. Most common}

basic pattern. F is fine texture; C is coarse texture. No structural control. Occurs on fine textured impervious material.

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Modification- _{of dendritic pattern. Tributaries of fourth and third order show Pincer-like}

curved forms. Occurs on igneos intrusions.

Anak sungai acara urutan keempat dan ketiga bentuk melengkung

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Subparallel-dendritic pattern. Coastal plain type. Flat bottomed broad short channels of limited extent. Elongated tributaries at the right developed due to tilt of the surface (arrow). Broad channels develop in fine sandy material.

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Von Bandat, “Aerogeology”

Dendritic-pinnate pattern.

There is no structural control. P is a plain surface: The material is sandy and clayey silt. (Ripley Cy., Indiana, U. S. Dept. of Agriculture)

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Dendritic-pectinate pattern. Featherlike design typical with loess. Parallel gullies with pearshaped headwater basins. Main stream in flat bottomed valley. P is a loss surface

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Modifications of dendritic pattern. Different designs develop in clayshale (C), sandy or silty clay (SC), and sand or sandstone (Ss). The different is in shape, ramification, type, texture and length of gullies. C is most ramified, tree-like, fine textured. S is more wide spaced, less ramified with short straight gullies. SC is finer textured with longer ramified gullies; a type between C and S (Sweetwater Cy., Wyoming, USGS)

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Angular drainage pattern. This basic type is also called a trellis pattern. A and B_.

are two tilted sandstone blocks. The pattern is fault controlled. It is found on fractured

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Angulate pattern, a modification of the angular pattern. The minor tributaries are parallel,

joining the main tributaries at obtuse angles. The pattern is fracture controlled and is found mostly in granular sediments, like sandstones in near horizontal attitudes.

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Contorted drainage pattern. The streams show reversed flow (arrows). The material is

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Parallel patterns. This basic pattern develops on fine textured material with steep slopes. Also along laminated formations of diffrent resistance, e.g., sand stone-shale belts, or on tilted valley fills. It is most common along steep clay scarps with obsequents streams.

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Subparallel pattern. The parallel tributaries join the main stream at an angle. This type is common coastal plains in fine material, or on lava streams.

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Radial drainage Pattern. The consequent streams flow from a central area in a radial design. The design is from an Indonesian volcano. The material is fine textured tuff and granular tuff at G. This basic pattern can be centrifugal (positive) on domes or uplifts and centripetal (negative) in basins.

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Annular drainage pattern. The rather rare design occurs on domes with concentric hard and soft upturned beds, or basins of similar composition.

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Radial, pincerlike-dendritic and annular drainage pattern on a small granite dome. Dashed lines with arrow are hard upturned bedded sediment, ridges. The central granite ridge with apex is at G. (Meade Cy., South Dakota)

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Sinkhole pattern develops on soluble rocks like limestone, gypsum, dolomite. Sink are usually roundish or oval shaped. Only short rudimentary surface channels develop. The shallow

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Drainage pattern in tropical Karst. Three different types of limestones (A, B, C) show three types of sinkholes and dissolved fractures. The dry surface channel is fracture controlled. The angular

boundary between the limestone types suggests fault contacts. ( After a Bataafsche Petroleum Maatschappij photograph)

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Dichotomic pattern. The streams radiating from a common point in a fan shaped manner depositing granular material by branching and multiple bifurcation (dichotomy). This design is found on alluvial fans and deltas.

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Anastomotic drainage pattern with meandering stream. Oxbow lakes (O) and

meander scars ( M) are on abandoned channels. Because of the collateral

commuting food channels, the pattern is called anastomotic. This depository pattern in common on floodplains may be, in part, structure controlled.

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This photograph shows a __________ stream channel a. meandering b. undercut c. gradient d. straight e. braided

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This image shows an area in the Appalachian Mountains in Pennsylvania. The type of drainage pattern that generally characterizes this region is __________

a. annular

b. Trellis

c. rectangular d. dendritic e. deranged

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This photograph shows part of the Kalahari Desert [Africa]. The drainage pattern is evident as a series of dark and light stripes that follow patterns of fossil sand dunes from an ancient desert. Parallel

channels intersect a larger stream following a fault on the left side of the image. Together, these geologic controls create a __________ drainage pattern.

a. trellis

b. rectangular

c. annular d. radial e. dendritic

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This karst region in Slovenia represents which type of drainage pattern? a. rectangular b. radial c. deranged d. annular e. dendritic f. trellis

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