Geomorphology Introduction PDF

GEOMORPHOLOGY PREPARED BY: GO, JAN JESSE V. 201211492 GEOMORPHOLOGY Geomorphology - 'the science dealing with landforms and their development' • Classification, description, nature, origin and development of landforms and their relationship to underlying structures • History of geologic changes a...

GEOMORPHOLOGY PREPARED BY: GO, JAN JESSE V. 201211492 GEOMORPHOLOGY Geomorphology - 'the science dealing with landforms and their development' • Classification, description, nature, origin and development of landforms and their relationship to underlying structures • History of geologic changes as recorded by these surface features It is the study of the relief of the Earth's crust. Basics of Geomorphology • Geomorphology studies Controlling factors: landform: process interactions at many scales. Tectonics Geology • Landforms and processes are affected by the history of the landscape. Time Climate Geomorphology and other Earth and Environmental Sciences Earth observation science IGeophysics 1~ J ~ IHydrology IGeomorphology I ~ -1C-1i-m-a-to_l_o-gy- -1S_e_d_im-e-n-to_l_o-gy--1 / 1Geochemistry I ____ IPedology I I Ecology Forces: Endogenic <--> Exogenic Exogenic processes • T.-a,n spott and Erosion iti o .n ~ ~ ,_ ~ % ....-=-- - - - - - * . , _---=----=--_:_~-~~-=--=~--~ . ~ · .::.... ·_ ....:.:.....~.,--::- ~__;;;--~- 1~~F~~~-- • . ·volcani c acti,v i ty Uplift · and fol ding: eif ·r ocks _s - . -· - · o : . • • ••_ ~~~~~~ f L.ate"r T e - cy.c Ung oT deposits -8!&~edit"neAtary .-o·ck.s IIVl,oun-r.e"i,n o u ·ildi ng 0rocesses - Endogenic processes ' "- • --- Classification of Landforms Geomorphological terrain units can be differentiated on the basis of the main 'diagnostic attributes': 1. Geomorphological origin 2. Relief characteristics 3. Lithology 10 Fundamental Concepts in Geomorphology 1. The same physical processes and laws that operate today operated throughout geologic time, although not necessarily always with the same intensity as now. UNIFORMITARIAN PRINCIPLE 2. Geologic structure is a dominant control factor in the evolution of landforms and is reflected in them. 3. To a large degree the earth's surface possesses relief because the geomorphic processes operate at different rates. 4. Geomorphic processes leave their distinctive imprint upon landforms, and each geomorphic process develops its own assemblage of landforms. I YOUTH 5. As different erosional agents act upon the earth's surface there is produced an II MATURITY III OLD AG£ orderly sequence of landforms. 6. Complexity of geomorphic evolution is more common than simplicity. IV REJUVENATION STAGES I:'\ THE GEOi\lORPHI C CYCLE OF A HDtm REGIO:'\ 7. Little of the earth's topography is older than Tertiary and most of it no older than Pleistocene. 8. Proper interpretation of present-day landscapes is impossible without a full appreciation of the manifold influences of the geologic and climatic changes during the Pleistocene. 9. An appreciation of world climates is necessary to a proper understanding of the varying importance of the different geomorphic processes. Concept 10. Geomorphology, although concerned primarily with present-day landscapes, attains its maximum usefulness by historical extension. AN ANALYSIS OF THE GEOMORPHIC PROCESSES GEOMORPHIC PROCESSES • Epigene or exogenetic processes • Hypogene or endogenetic processes • Extraterrestrial processes EPIGENE OR EXOGENETIC PROCESSES Gradational processes: •!•Aggradation by: running •!•Degradation water; groundwater; • Weathering waves, currents, tides, • Mass wasting or gravitative transfer and tsunami; wind; and • Erosion by: running water; groundwater; waves; currents; tides; and tsunami. glaciers •!•Work of organisms, including man Hypogene or endogenetic processes • Diastrophism • Vulcanism Ext rate rrestri a I processes • Infall of meteorites Gradational Processes • Include all those processes which tend to bring the surface of the lithosphere to a common level • Two categories of gradation: • Degradation - those which level down • Aggradation - those which level up Degradation • Weathering - disintegration or decomposition of rock in place • Mass wasting-bulk transfer of masses of rock debris down slopes under the direct influence of gravity (ex. landslides, debris avalanche, earthflows, mudflows, etc.) • Erosion- refer to various ways by which the mobile agencies obtain and remove rock debris Rock Weathering • Factors that influence the type and rate of rock weathering: 1. Rock structure 2. Climate 3. Topography 4. Vegetation Physical weathering processes: • Expansion resulting from unloading • Crystal growth • Thermal expansion • Organic activity • Colloid plucking Chemical weathering processes: • Hydration - absorption of water • Hydrolysis - formation of hydroxyl • Oxidation - process of combining with oxygen • Carbonation- introduction of carbon dioxide • Solution Mass Wasting • Slow flowage types - ex. Creep (soil, talus, rock, rock-glacier and solifluction) • Rapid flowage types - earthflow, mudflow, debris avalanche • Landslides - (slump, debris slide, debris fall, rockslide, rock fall) • Subsidence Diastrophism Two (2) types of diastrophic • • Includes the movement of molten processes: rock or magma onto or toward the Orogenic - mountain- earth's surface. building with deformation • Vulcan ism Epeirogenic - regional uplift without important deformation Impact of Meteorites • Land forms of this origin are rather rare but approx. 50 well-substantiated meteorite craters are known; unique because they're produced by extraterrestrial agents, although the earth's gravitative attraction was responsible for the infall of the meteorites. Topographic Effects of Organisms • Man-made quarries, road cuts and fills • Bomb craters • Reefs built by corals and other organisms • Mounds built by ants, termites, prairie dogs, gophers, birds, etc. • Vegetation - final filling of a lake with vegetation results in peat bogs and marshes SOME LAND FORMS OF DENUDATIONAL ORIGIN @ Footslopes - gently inclined (pedi-) planated (erosional surfaces; veneered with debris (strewn with rock fragments); occur between mountain fronts and valley or basin bottoms. @ lnselbergs - isolated residual hills; generally bare and rocky surrounded by plains @ Peneplains - nearly flat or broadly undulating plains ; represent the penultimate stage of old age produced by weathering and erosion. SOME AGGRADATIONAL LAND FORMS @ Fans (excluding rock fans) - accumulations of debris brought down by gravity and/or by streams descending through steep ravines. If deposited primarily by gravity the term "scree fan" applies; if by stream activity, the term "alluvial fan" is most appropriate. @ lnfilled valleys - valleys with almost flat bottoms; filled with debris due to inability of the streams to transport the enormous load into the basin, lake or sea, hence, the absence of pronounced runoff