Week 06 Landforms, Weathering, Karst (for laptops) PDF

Physical Geography: Landforms, Weathering, Karst 10/7/2024 – 10/9/2024 PROFESSOR PETE PULEO 1 Formation of Landforms 2 Learning Objectives Describe the major processes that shape landforms and landscapes Explain the importance of gravity as a driving for...

Physical Geography: Landforms, Weathering, Karst 10/7/2024 – 10/9/2024 PROFESSOR PETE PULEO 1 Formation of Landforms 2 Learning Objectives Describe the major processes that shape landforms and landscapes Explain the importance of gravity as a driving force for erosion and how gravity-driven erosion is influenced by the slope and relief of the land surface Summarize the interactions among tectonic activity, weathering, and erosion 3 Landforms Features of Earth's topography that can be distinguished and studied as a single unit Examples: riverbed, glacial outwash plain, plateau 4 Landscapes A combination of landforms Often described as where the landscape exists and the processes that formed it (E.g., coastal landscape) 5 Landforms vs. Landscapes Identify the landforms in this mountainous landscape (Rocky Mountains) 6 Landforms vs. Landscapes Landforms: Mountains, lake basin, ridge, beach 7 Weathering vs. Erosion Weathering – The physical or chemical breakdown of rock in place Erosion – The breakdown of rock and movement of rock/sediment Earlier rain weathering/eroding granite 8  Weathering vs. Erosion https://www.substrata.us/blog/types-of-soil-erosion-and-environmental-impact 9 Mass Movement The downslope movement of materials on Earth's surface under the force of gravity (E.g., lahars, landslides) 10  Running Water The most influential agent of weathering and erosion https://knowablemagazine.org/content/article/physical-world/2019/deeper- understanding-grand-canyon 11  Running Water Streams can carry massive amounts of sediment over long distances https://www.nesdis.noaa.gov/news/sediment-flows-along-the-mississippi-river- delta 12  Flowing Ice Glaciers and ice sheets of the past scour the surface, shape valleys, and transport rock https://www.nps.gov/articles/valleyandpiedmontglaciers.htm 13 Wind Gusts can effectively move sediments like sand, silt, and clay but only very slowly weather rock 14  Coastal Waves Waves move loose rock/sediment and bash it against solid rock on the shoreline, but they are not very effective at breaking rock alone https://www.interlochenpublicradio.org/news/2019-10-11/lake-michigan- homeowners-wait-in-quiet-terror-as-high-water-levels-eat-away-property 15  Deposition When sediments in motion are left in place after being carried by water, wind, ice, etc. https://www.usgs.gov/media/images/sediment-diagram-source-sink 16  What Determines Where Eroded Material is Deposited? Force of gravity on sediment in relation to force from moving water, ice, or wind https://www.aplusphysics.com/courses/honors/ucm/gravity.html 17  Relief The local range in elevation (highest - lowest) A high relief is often associated with steep slopes https://project.geo.msu.edu/geogmich/relief.html 18 Relief and Erosion High relief and steep slopes are associated with higher rates of erosion due to greater exposure and faster moving water, ice, or wind 19 https://kmalexander.com/2024/02/28/we-need-to-talk-about-your-rivers/ 20  Tectonics and Erosion: Uplift Uplift at continental – continental crust collisions leads to rock being more exposed to water/wind/ice for erosion https://www.geo.fu- berlin.de/en/v/geolearning/mountain_building/weathering/Erosion7/index.html 21 Tectonics and Erosion: Subsidence Land falling at continental rift margins and subduction zones leads to large basins that can accumulate sediments deposited via gravity 22 Tectonics and Erosion 23  Activity 1 Description Work with a partner to identify the landforms in the following image and describe how they may have formed https://episcodon.net/@jnmast/110242941242198172 24  Activity 1 Solution Mountains: tectonic uplift, erosion from wind/water/ice Valley: erosion from glaciers and rivers River Islands/Bars: sediment deposited by braided stream https://episcodon.net/@jnmast/110242941242198172 25 Activity 2 Description Independently read through the list of landforms on this website (https://worldlandforms.com/landforms/list-of-all-landforms/) and select one to answer the following questions before sharing your answers with a partner: 1) What is the name of the landform you chose? 2) How is that landform defined/described? 3) Where on Earth is an example of your landform (find a picture)? 4) How and when did that example form? 26 Weathering Processes 27 Learning Objectives Explain the major processes of mechanical weathering Describe the reactions involved in chemical weathering and the nature of the products of weathering Summarize the concept of biological weathering List the general environmental controls over weathering processes and discuss how they influence the geography of weathering 28 Mechanical/Physical Weathering The destruction of rock from stress being applied 29  Wind Weathering and erosion https://www.geo.fu- berlin.de/en/v/geolearning/mountain_building/weathering/Erosion/index.html 30  Wind Deflation Erosion https://www.geo.fu- berlin.de/en/v/geolearning/mountain_building/weathering/Erosion/index.html 31  Salt Wedging Salty waves break up rock by physical action and when salt precipitates in cracks https://www.twinkl.nl/teaching-wiki/mechanical-weathering 32  Freeze-Thaw or Frost Action https://www.researchgate.net/figure/Process-of-freeze-thaw-weathering-of- rock_fig1_320735092 33  Temperature Change Heating expands and cooling contracts rocks which can lead to weathering https://www.twinkl.nl/teaching-wiki/mechanical-weathering 34 Erosional Features: Blockfield Rock fragments near original site of weathering 35 Erosional Features: Talus Rock fragments near original site of weathering moved by mass wasting down cliffs 36 Erosional Features: Exfoliation 37 Erosional Features: Exfoliation Outer layer of rock breaking due to thermal expansion and contraction 38 Chemical Weathering The process of breaking down rock by chemical reactions 39 Types of Chemical Weathering 40 Types of Chemical Weathering 41  Types of Chemical Weathering Silicate Mineral -> Clay https://link.springer.com/chapter/10.1007/978-3-319-66444-6_7 42 Types of Chemical Weathering 43  Chemical Weathering and Surface Area As the surface area of exposed rock increases, so does the rate of chemical weathering https://flexbooks.ck12.org/cbook/ck-12-middle-school-earth-science-flexbook- 2.0/section/13.3/primary/lesson/chemical-weathering-ms-es/ 44  Resistance to Chemical Weathering Different rocks have different minerals which are susceptible to chemical weathering at different rates Example: In granite, quartz resists chemical weathering while feldspar is more chemically reactive due to their differing chemistry and bond strength https://en.wikipedia.org/wiki/Granite 45 What Landform of Eroded Sediments Shows that Quartz is Highly Resistant to Weathering? 46 What Landform of Eroded Sediments Shows that Quartz is Highly Resistant to Weathering? 47 Biological Weathering Physical or chemical weathering mediated by organisms 48  Examples of Biological Weathering Root wedging https://bbc.co.uk/bitesize/guides/zt6r82p/revision/2 49 Examples of Biological Weathering Root wedging 50  Examples of Biological Weathering Burrowing animals https://en.wikipedia.org/wiki/Burrow 51  Examples of Biological Weathering Human land use change https://studentassembly.org/weathering-and-erosion-how-are-they-different/ 52  Geography of Weathering Frost wedging can only occur in locations with below freezing temperatures https://www.weather5280.com/2021/02/22/the-last-week-was-quite-cold- across-much-of-the-u-s-but-was-it-extreme 53  Geography of Weathering Salt wedging is concentrated near ocean and hypersaline lake environments https://www.usgs.gov/media/images/study-saline-lakes-great-basin-desert-area 54  Geography of Weathering Salt wedging can occur anywhere where there are high rates of evaporation (like deserts) https://www.usgs.gov/media/images/study-saline-lakes-great-basin-desert-area 55  Geography of Weathering Bedrock type influences weathering rates (E.g., granite is resistant while limestone is not) https://geologictimepics.com/2020/03/27/touring-the-geologic-map-of-the- united-states/ 56  Geography of Weathering Chemical weathering is increased with wetter conditions https://learn.weatherstem.com/modules/learn/lessons/85/13.html 57  Geography of Weathering Chemical weathering is increased with hotter conditions https://www.climate.gov/news-features/featured-images/new-maps-annual- average-temperature-and-precipitation-us-climate 58 Activity 3 Description Work independently to draw salt wedging in action on a boulder. Have three different diagrams of three different stages in the process (before, during, after). Be sure to describe what is happening in each step. Then, compare your drawing with a neighbor and discuss. 59 Activity 3 Solution 60 Activity 4 Description Independently read through the following article and look through the images (https://education.nationalgeographic.org/resource/weathering/) to answer the questions below: 1) What is a bornhardt? Where is the example in the article from? 2) What country is the Wave Rock photo taken in? 3) What kind of weathering produces a honeycomb pattern on rock? 61 Activity 4 Solution 1) What is a bornhardt? Where is the example in the article from? Tall, domed, isolated rocks formed from exfoliation often in tropical areas Rio de Janeiro, Brazil 62 Activity 4 Solution 2) What country is the Wave Rock photo taken in? Australia 63 Activity 4 Solution 3) What kind of weathering produces a honeycomb pattern on rock? Haloclasty, or weathering from salt 64 Karst 65 Learning Objectives Discuss the processes that produce karst landscapes and the environmental factors that influence them List the landforms that characterize karst landscapes and describe their formation Relate karst processes to the development of extensive underground cave systems 66 Karst Landscapes formed by erosion of carbonate rock from groundwater movement Cenotes (sinkholes) and caves in Mexico 67  Karst Chemistry Dissolution: Material dissolving and being carried in solution (often water) https://www.researchgate.net/figure/Illustration-of-dissolution-and- precipitation-regimes-in-the-karst-system-Figure_fig2_317009377 68  Karst Chemistry Precipitation: Rocks and minerals forming out of their previously dissolved state in water https://www.researchgate.net/figure/Illustration-of-dissolution-and- precipitation-regimes-in-the-karst-system-Figure_fig2_317009377 69 Karst Development Wetness influences karst development Wetter climates allow for more water to percolate into rock and lead to dissolution 70 Karst Development Temperature influences karst development Colder climates cause water to freeze and limits dissolution 71 Karst Development Relief influences karst development Moderate to high relief areas allow for greater groundwater flow and saturated water to be replaced with fresh water 72 Karst Development Rock type influences karst development Highly fractured and easily chemically weathered limestone is very conducive to karst formation 73  Karst Landscape Development https://www.nps.gov/subjects/caves/karst-landscapes.htm 74  Karst Landscape Development https://www.nps.gov/subjects/caves/karst-landscapes.htm 75  Karst Landscape Development https://www.nps.gov/subjects/caves/karst-landscapes.htm 76  Karst Landscape Development https://www.nps.gov/subjects/caves/karst-landscapes.htm 77  Karst Landforms: Caves An opening in bedrock that has interior space and is large enough for a person to enter https://www.nps.gov/places/historic-entrance-of-mammoth-cave.htm 78  Karst Landforms: Cave Features Stalactites – Grow from cave ceiling via calcite precipitating from saturated water Stalagmites – Grow from cave floor via calcite precipitating from saturated water Growth factors: Temperature and rainfall amount https://www.nps.gov/ozar/learn/education/speleothems.htm#:~:text=Stalactites %20grow%20down%20from%20the,through%20cracks%20in%20the%20rock. 79 Karst Landforms: Sinkholes Solution Sinkholes – Depressions from dissolution of surface rock, form slowly Collapse Sinkholes – Depressions from subsurface dissolution of rock and structural failure, can form suddenly 80  Karst Landforms: Sinkholes Uvala – Network of joined sinkholes https://www.researchgate.net/figure/a-The-evolution-of-compound-sinkholes- left-into-a-uvala-right-through-enhanced_fig1_363915051 81 Karst Landforms: Towers Cone shaped, steep sided hill Form as limestone blocks are fractured and dissolved at different rates Cockpit Karst – Irregular, steep sided depressions between towers 82 Karst Landscapes Temperate Karst – Temperate climates cause karst to slowly form. Characterized by disappearing streams, jagged rocks, sinkholes, and extensive caves 83 Karst Landscapes Tropical Karst – Warm, humid climates cause rapid development and large-scale features (limestone towers in Vietnam) 84 Karst Landscapes Caribbean Karst – Flat, coastal limestone is eroded by groundwater, causing collapse that leaves surface depressions (Florida) 85  Activity 5 Description Look at the following image and determine what kind of karst landscape it fits under (Caribbean, Tropical, or Temperate). Describe the likely climatic conditions and speed of formation. http://www.tropicalbats.com/tropicalbats-blog/cockpit-karst-in-the-dominican- republic 86  Activity 5 Solution Look at the following image and determine what kind of karst landscape it fits under (Caribbean, Tropical, or Temperate). Type: Tropical karst (towers and cockpit karst landscape) http://www.tropicalbats.com/tropicalbats-blog/cockpit-karst-in-the-dominican- republic 87  Activity 5 Solution Describe the likely climatic conditions and speed of formation. Climate: Hot and wet Speed: Relatively fast http://www.tropicalbats.com/tropicalbats-blog/cockpit-karst-in-the-dominican- republic 88 Activity 6 Description Watch this video (https://vimeo.com/363068598) to learn about cave diving and research efforts in Mexican karst landscapes. 89  Multiple Choice Practice Qs Take ~ 1 minute to independently think about and write down an answer to the question on the board. Then, turn to a partner and discuss your reasoning for choosing that answer. Write a second answer after you have discussed your thoughts with a partner (its okay to write the same answer twice or change your answer, just be sure to have two answers per question). Finally, we will discuss the correct answer as a class. Be sure to have your name and date on top and hand in before you leave. 90 Question 1 Areas of high relief tend to have: a. steep slopes b. high rates of erosion c. low rates of erosion d. both (a) and (b) 91 Solution 1 Areas of high relief tend to have: a. steep slopes b. high rates of erosion c. low rates of erosion d. both (a) and (b) 92 Question 2 Weathering begins to wear down rocks: a. after mountain formation b. during and after the mountain formation c. only after glaciers form on the mountains d. when mountains promote higher wind speeds 93 Solution 2 Weathering begins to wear down rocks: a. after mountain formation b. during and after the mountain formation c. only after glaciers form on the mountains d. when mountains promote higher wind speeds 94 Question 3 When weeds and grass break through sidewalks and driveway concrete, it is an example of: a. a biological form of chemical weathering b. a physical form of mechanical weathering c. poor concrete rather than weathering d. a biological form of physical weathering 95 Solution 3 When weeds and grass break through sidewalks and driveway concrete, it is an example of: a. a biological form of chemical weathering b. a physical form of mechanical weathering c. poor concrete rather than weathering d. a biological form of physical weathering 96 Question 4 When rock expands, sheets of outer rock peels off of outcrops or boulders by a. frost action b. oxidation c. salt wedging d. exfoliation 97 Solution 4 When rock expands, sheets of outer rock peels off of outcrops or boulders by a. frost action b. oxidation c. salt wedging d. exfoliation 98 Question 5 Karst topography involves mostly which of the following type of weathering: a. biological b. chemical c. mechanical d. none of these 99 Solution 5 Karst topography involves mostly which of the following type of weathering: a. biological b. chemical c. mechanical d. none of these 100 Question 6 This gas leads to the dissolution of the rock in karst landscapes: a. O2 b. N2 c. H d. CO2 101 Solution 6 This gas leads to the dissolution of the rock in karst landscapes: a. O2 b. N2 c. H d. CO2 102