GAYA, PROSES, DAN MORFOLOGI PERMUKAAN

BUMI

AKHMAD ZAMRONI

Landslide event in Shiaoling Village during Morakot Typhoon in 2009 E-TEC2

Proses Geomofologi

• Proses geomorfologi adalah seluruh perubahan

baik secara fisik maupun kimiawi yang dialami

permukaan bumi.

• Penyebab proses geomorfologi (geomorphic agent)

terdiri dari tenaga asal luar (eksogen) dan tenaga

asal dalam (endogen).

Tenaga dan

proses

geomorfologi

Tenaga dan proses

Eksogen

Tenaga dan proses

Endogen

Pelapukan

(weathering)

Erosi

Gerak masa batuan

(masswasting)

Diatrofisme

(tektonisme)

Vulkanisme

Gaya Endogen

• Gaya endogen adalah gaya dan proses geomorfologi

yang berasal dari dalam bumi, gaya ini muncul akibat

adanya perubahan-perubahan yang terjadi di bagian

bawah dari kerak bumi.

• Proses endogen membentuk perubahan relief bumi

dengan proses volkanisme, plutonisme dan tektonik

(diatrofisme).

A. Endogenous Processes

Endogenous Processes are large-scale landform

building and transforming processes

– they create relief.

1. Igneous Processes

a. Volcanism: Volcanic eruptions Volcanoes

b. Plutonism: Igneous intrusions

2. Tectonic Processes (Also called Diastrophism)

a. Folding: anticlines, synclines, mountains

b. Faulting: rift valleys, graben, escarpments

c. Lateral Faulting: strike-slip faults

Earthquakes evidence of present-day tectonic activity

B. Exogenous Processes

Also called Gradational Processes, they comprise degradation

and aggradation – they modify relief

a continuum of processes – Weathering Mass

Wasting Erosion Transportation Deposition

these processes are carried through by Geomorphic

Agents: gravity, flowing water (rivers), moving ice

(glaciers), waves and tides (oceans and lakes), wind,

plants, organisms, animals and humans

1. Degradation Processes Also called Denudation Processes

a. Weathering , b. Mass Wasting and c. Erosion and

Transportation

2. Aggradation Processes

a. Deposition – fluvial, eolian, glacial, coastal

Degradation Processes:

Weathering, Mass Wasting,

Erosion and Transportation

Relationship:

Weathering

Mass Wasting

Erosionand

Transportation

Together,

these processes are

responsible for

Denudationof Earth’s surface

Pelapukan (Weathering)

• Pelapukan adalah segala macam perubahan sifat batuan

baik secara fisik maupun kimiawi karena perubahan

cuaca (temperatur dan kelembaban). Hasil akhir dari

proses pelapukan adalah terbentuknya tanah.

• Proses pelapukan dibedakan menjadi :

1. Pelapukan fisis/ mekanis

2. Pelapukan kimia

3. Pelapukan biologi

Physical or Mechanical Weathering Disintegration and decay of rocks via weather elements: high

temperatures, extreme cold and freeze-thaw cycles

No change in chemical composition of rocks

• Exfoliation – due to thermal expansion/contraction and/or release of

pressure when buried rocks are uplifted and exposed

e.g., Exfoliation Dome (Stone Mountain, GA) and Exfoliation Sheets (Sierra Nevada)

• Frost Wedging

• Salt Wedging

Chemical Weathering decomposes rocks through a chemical change in its minerals

Oxidation – important in iron-rich rocks – reddish coloration like rust

Hydrolysis – igneous rocks have much silica which readily combines with water

Carbonation and Solution – carbon dioxide dissolved in water reacts with carbonate rocks to create a solubleproduct (calcium bicarbonate)

Biological Weathering

– plants and animals contribute to weathering.

Roots physically break or wedge rock

Lichens (algae and fungi living as single unit), remove minerals and weaken rock by releasing acids

Burrowing animals can increase weathering.

Lichens

Erosi

• Erosi adalah pengikisan dan pemindahan hancuran

masa batuan secara alami dari suatu tempat ke

tempat yang lain oleh suatu kekuatan pengangkut di

atas permukaan bumi.

• Faktor-faktor yang mempengaruhi terjadinya erosi:

1. Iklim

2. Relief

3. Tutupan vegetasi

4. Sifat batuan

5. Pelaku erosi

EROSION and TRANSPORTATION

– Various Geomorphic Agents, associated Processes,

and resulting Erosional Features

• Flowing Water – Fluvial Morphology

Humid regions:

Perennial streams and entrenched

channels, rapids, waterfalls, plunge

pools, potholes, meandering streams,

bank erosion, oxbow lakes, etc.

• Wind – Eolian Landscapes

deflation hollows, ventifacts, yardang, etc

• Tides and Waves – Coastal Morphology

Sea cliffs, sea caves, sea arches, sea stacks, wave-cut

beaches, etc..

• Moving Ice – Glacial Morphology

glacial troughs (U-shaped valleys), hanging valleys, glacial

lakes,.

(sumber : glencoe earthsience)Agen utama erosi

Erosi oleh kegiatan konsruksi

Gerak Masa Batuan (masswasting)

• Gerak Masa Batuan (masswasting) disebut juga

gerakan massa (mass movement) adalah berbagai

jenis gerakan masa menuruni lereng (jatuh, runtuh

atau meluncur ke bawah) sebagai akibat gaya tarik

gravitasi.

• Menurut Goudie (2004) proses gerakan masa ini

tidak memerlukan medium transport seperti air, angin

atau es.

Bentuk dan Roman Bumi

• Gaya dan proses asal dalam (endogen) dan asal luar (eksogen),

menyebabkan bentuk muka bumi berubah sepanjang sejarah

geologi.

• Sebagai akibat dari gaya endogen dan eksogen tersebut

mengakibatkan terjadinya perbedaan antara luas samudera dan

daratan serta perbedaan elevasi morfologi permukaan bumi.