weathering

Information about weathering

Published on January 20, 2008

Author: Urania

Source: authorstream.com

Content

Weathering:  Weathering Weathering is the physical breakdown and chemical alteration of rocks and minerals. Weathering happens on or near the surface. Weathering is caused by Atmospheric gases Water Acids Living organisms There are two types of weathering, mechanical and chemical Slide2:  Why is Weathering important? It produces the raw products for both Sedimentary rocks and soils It also products some important mineral resources like aluminum ores What is erosion? Erosion is the removal of weathered material from the weathering source area. Slide3:  Mechanical Weathering This is the physical breaking of bedrock into smaller pieces. Types of Mechanical weathering include Frost wedging Salt crystal growth Pressure release Thermal expansion & contraction Activities of organisms Slide4:  Frost wedging: This occurs in regions where temperatures fluctuate above and below freezing Slide6:  The material produced by frost wedging accumulates as talus at the base of mountains forming a talus slope. Slide8:  Pressure release: This common in intrusive rocks that were formed deep under ground. E.g. granite batholiths. When this rock is exposed to the surface by uplift and erosion the rock expands and sheet joints form parallel to the rock surface. This is also called exfoliation. Slide9:  Exfoliation domes form as the slabs of rock slip or slide off the bedrock. E.g. Yosemite Slide11:  Thermal expansion and contraction: A common feature in desert environments where temperatures can vary by as much as 30°C (86 °F) Rock is a poor conductor of heat so the outside expands more than the interior. But this is not an important agent of mechanical weathering. Slide12:  Chemical Weathering This is the decomposition of the rocks by chemical alteration of the bedrock. Water (H2O) Acids (H2SO4, HNO3 , H2CO3) atmospheric gases (carbon dioxide and oxygen) and organism are important in chemical weathering. Slide13:  Water: Some minerals will dissolve in water like the mineral halite (NaCl) H2O + NaCl  Na+ + Cl- This minerals are transported as dissolved salts in water. Slide14:  Living organisms: Many minerals will not dissolve in water, but they will in acid. Lichen is a fungi and algae living together. Lichen covered rocks weather faster than rocks not covered by lichen. Why is this? During the process of photosynthesis, lichen removes CO2 from the atmosphere. This gas then reacts with water to form an acid. Slide15:  The chemical reaction: Water + carbon dioxide  Carbonic acid H2O CO2 H2CO3 Carbonic acid  hydrogen ion + bicarbonate ion H2CO3 H+ HCO3- Rocks that dissolve in acid easily are Limestone and marble. CaCO3 + HCl  CO2 + CaCl2 + H2O Slide16:  Another important chemical reaction is oxidation Iron minerals in the rock react with oxygen to form iron oxides This often appears as red stains in the rock Fe 2+ + O2  Fe2O3 Slide17:  Plant action: 1.Tiny root hairs seek out small cracks and pits in rock. 2.Once the root hairs find a place they grow and expand. 3.The expansion causes great pressure and cracks the rock. Slide18:  Factors controlling Chemical Weathering: Surface area of rock Climate Rock type Slide19:  Surface area: The greater the surface area the more area of the rock that is exposed to the elements and so it weathers faster. Rocks with many joints and fractures will weather faster. Slide20:  Climate and the speed of weathering The wetter and warmer the climate the faster chemical weathering will occur. So where in the world we you find the fastest weathering? Tropical regions with high rainfall and warm temperatures. Weathering here can extend to depths of several tens of meters. In cold areas and deserts it will only go down a few centimeters! Slide21:  Soil: What is soil? Soil is a mixture of: Air, water and its solutes, mineral particles from parent bedrock, decaying organic matter, And organism responsible for its decay. Soil is a living skin! Slide22:  Soil Horizons Slide23:  Soil Horizons: O composed mainly of organic material a few centimeter thick not fully decomposed A Top soil organic matter biological activity, bacteria, plant roots, fungi, worms etc. minerals can be leached by water into lower layers B sub-soil fewer organisms soluble minerals build up here C partially altered bedrock with little organic matter Slide24:  The most important factor effecting soil formation is Climate Different climates produce different soils Slide25:  Soils and climate: Tropical climate have laterite soils. These are deep, but not not very fertile as the minerals have been leached out. Nutrients are in the O horizon. The soil is often a deep red color from weathering. If soil is rich in aluminum, then leached aluminum hydroxide may accumulate in the B horizon. as bauxite (aluminum ore). Slide26:  Humid areas form pedalfer soils. usually rich in organic matter abundant water has leached most soluble minerals from A horizon Pedocal soils are found in arid and semi-arid areas Western and southwest regions of the USA Contain less organic matter than pedalfers Slide27:  Soil Degradation: Soil is one of the most important factors in human civilization. Its mismanagement and destruction has been the collapse of many civilizations in the past. E.g. Sumeria in Iran/Iraq Easter Island Teotihuacan Maya Slide28:  The decrease in soil productivity or loss of soil to erosion is called soil degradation

Related presentations


Other presentations created by Urania

rocks ppt
14. 01. 2008
0 views

rocks ppt

Haydn Shaw presentation
09. 01. 2008
0 views

Haydn Shaw presentation

Cosmetica presentacion gris
10. 01. 2008
0 views

Cosmetica presentacion gris

what is femp 5B1 5D
11. 01. 2008
0 views

what is femp 5B1 5D

private sector
12. 01. 2008
0 views

private sector

S06 Lec5a rocksmet
14. 01. 2008
0 views

S06 Lec5a rocksmet

ma dissertation
14. 01. 2008
0 views

ma dissertation

Chapter 6 day 3
14. 01. 2008
0 views

Chapter 6 day 3

chapt 3 power presentation
14. 01. 2008
0 views

chapt 3 power presentation

Music 2 Powerpoint
15. 01. 2008
0 views

Music 2 Powerpoint

suips
17. 01. 2008
0 views

suips

lead awareness
18. 01. 2008
0 views

lead awareness

4 Rafi Ahmad
19. 01. 2008
0 views

4 Rafi Ahmad

wind
21. 01. 2008
0 views

wind

TheAfterlife
15. 01. 2008
0 views

TheAfterlife

Rahman PPT
23. 01. 2008
0 views

Rahman PPT

biotech
24. 01. 2008
0 views

biotech

gbr07 shen gufg 01
04. 02. 2008
0 views

gbr07 shen gufg 01

SBS UAE Presentation
04. 02. 2008
0 views

SBS UAE Presentation

unit 7
05. 02. 2008
0 views

unit 7

a3
08. 02. 2008
0 views

a3

Color seminar
11. 02. 2008
0 views

Color seminar

Life on a cotton plantation
25. 01. 2008
0 views

Life on a cotton plantation

17xsl
15. 01. 2008
0 views

17xsl

VMB SEMIPLENARY SHEFFIELD 2006
16. 01. 2008
0 views

VMB SEMIPLENARY SHEFFIELD 2006

OB ch03
29. 01. 2008
0 views

OB ch03

The Rosary Prayers
29. 01. 2008
0 views

The Rosary Prayers

Ogilvy Presentation
06. 02. 2008
0 views

Ogilvy Presentation

DENA ozone
20. 02. 2008
0 views

DENA ozone

MAPLD2004 Paper198
28. 02. 2008
0 views

MAPLD2004 Paper198

EdgarSpresentation
25. 01. 2008
0 views

EdgarSpresentation

Manzotti
29. 02. 2008
0 views

Manzotti

Peter Loveland Presentation
17. 01. 2008
0 views

Peter Loveland Presentation

PARQUES TEMÁTICOS
19. 03. 2008
0 views

PARQUES TEMÁTICOS

ae bg sec1
20. 03. 2008
0 views

ae bg sec1

edwards
07. 02. 2008
0 views

edwards

c1 3
24. 03. 2008
0 views

c1 3

ecology collab chapter 5 lesson
03. 04. 2008
0 views

ecology collab chapter 5 lesson

Andean Civilizations
13. 02. 2008
0 views

Andean Civilizations

GEOL3026 3
28. 03. 2008
0 views

GEOL3026 3

Realization of Olympism DR CHANG
14. 04. 2008
0 views

Realization of Olympism DR CHANG

182AWHRETraining
17. 04. 2008
0 views

182AWHRETraining

japan60s
21. 04. 2008
0 views

japan60s

employ scs place shaping 110907
22. 04. 2008
0 views

employ scs place shaping 110907

articles 71023 2
24. 04. 2008
0 views

articles 71023 2

2008 PS Summer
10. 03. 2008
0 views

2008 PS Summer

Michael Payne IOC
30. 04. 2008
0 views

Michael Payne IOC

WLOCHY ETAP 17 04 2007
02. 05. 2008
0 views

WLOCHY ETAP 17 04 2007

JTB260401Singapore2
27. 03. 2008
0 views

JTB260401Singapore2

pps 326
14. 02. 2008
0 views

pps 326

IsiorhoHawii2Group
05. 02. 2008
0 views

IsiorhoHawii2Group

29 Lectures PPT
12. 02. 2008
0 views

29 Lectures PPT

procanal
20. 02. 2008
0 views

procanal

WreckedCenters Philly
15. 03. 2008
0 views

WreckedCenters Philly

Brain sportsconcussion
23. 01. 2008
0 views

Brain sportsconcussion

Semeria history pool
18. 01. 2008
0 views

Semeria history pool

royster
09. 01. 2008
0 views

royster

IT Scenario Orissa
31. 01. 2008
0 views

IT Scenario Orissa

HST353 15
14. 02. 2008
0 views

HST353 15

marshall 25june2007
23. 01. 2008
0 views

marshall 25june2007

Rachel Ellaway Virtual Patients
04. 02. 2008
0 views

Rachel Ellaway Virtual Patients

ep050320m
08. 04. 2008
0 views

ep050320m

heathers green cleaners training
22. 01. 2008
0 views

heathers green cleaners training

Kishan
24. 01. 2008
0 views

Kishan