1 Shoreline Landforms 2. 2 Emergent v. Submergent 2. 3 Wavecutting 3. 4 Planview 4. 5 Marine Terraces 5. 6 California 7. 7 Tombolos, Sea Stacks 8

Size: px

Start display at page:

Download "1 Shoreline Landforms 2. 2 Emergent v. Submergent 2. 3 Wavecutting 3. 4 Planview 4. 5 Marine Terraces 5. 6 California 7. 7 Tombolos, Sea Stacks 8"

Myles Jennings
5 years ago
Views:

1 Shorelines November 9, 2008 Contents 1 Shoreline Landforms 2 2 Emergent v. Submergent 2 3 Wavecutting 3 4 Planview 4 5 Marine Terraces 5 6 California 7 7 Tombolos, Sea Stacks 8 8 Active Processes 9 9 Emergence and Subduction 9 1

2 10 Submergent Shoreline Deposits and Landforms Bars and Spits Beaches Intertidal Mud Flats and Marshes Shoreline Processes Waves Gravity Waves Littoral Drift Tidal currents 17 1 Shoreline Landforms Shoreline types Emergent shorelines that form in regions of relative uplift of the land Submergent shorelines in regions of relative sea level rise 2 Emergent v. Submergent 2

3 Emergent shorelines are often relatively straight with few wave/tide landforms, whereas submergent are often embayed and irregular with many wave/tide landforms 3 Wavecutting 3

4 Wave cutting can predominate on emergent shorelines... 4 Planview 4

5 Cutting may be concentrated on headlands, while deposition occurs in embayments 5 Marine Terraces 5

6 Marine terraces are typical on emergent shorelines, as land uplifts out of the surf zone 6

7 6 California Wavecut terraces and steep cliffs on the California coast 7

8 7 Tombolos, Sea Stacks Tombolos occur where small amounts of deposition occur between the coast and sea stacks or shipwrecks, as in this case 8

9 8 Active Processes Emergent shorelines may arise because of active tectonic or volcanic processes at the shore, however, this is not always the case... 9 Emergence and Subduction 9

as in subduction zones, where vast regions are emergent, but not near the plate boundary 10 Submergent Shoreline Deposits and Landforms Submergent shorelines generally have more depositional features

10 as in subduction zones, where vast regions are emergent, but not near the plate boundary 10 Submergent Shoreline Deposits and Landforms Submergent shorelines generally have more depositional features than do emergent shorelines Shoreline deposits are predominantly wellsorted, stratified sand and gravel bodies with cross-bedding and planar bedding very similar to that in deltas In planform view, trend of deposits is parallel to the shoreline so that landforms generally parallel the coastline Bars and spits 10

11 Beach birm 11 Bars and Spits Landforms resulting from longshore drift are bars, barrier islands and spits Rip current Cross current caused by focussing of ebbing wave energy through the offshore bar i.e., bars have breaks in them 12 Beaches 11

12 Beach berms develop in wave-dominated environments with good sediment supply 12

13 13 Intertidal Mud Flats and Marshes Intertidal mud flats and marshes are common in tide-dominated coastal environments 13

14 At low tide, especially during the slack water interval before the tide reverses, fine sediment is stirred by the surf and deposited by streams on the intertidal flats The fine sediment flocculates in the salt water (cemented by Na+) and resists erosion during the rising tide Mudflats are colonized by salt-tolerant plants that reduce wave and tidal energy and trap sediment 14 Shoreline Processes Main process transporting material along the shoreline to develop landforms Tidal currents and longshore drift are the two main types of currents. Drift is related to waves. 14

15 15 Waves Eternal Reefs from Surfer magazine Caused by wind Most important controlling factor of wave size is fetch, the length of water over which the wind blows Windspeed and duration are also factors 16 Gravity Waves 15

$Wave refraction is caused by oblique impingement of waves on the shoreline 17 Littoral Drift One component of the wave motion makes breaking waves,$

16 Wave refraction is caused by oblique impingement of waves on the shoreline 17 Littoral Drift One component of the wave motion makes breaking waves, the other makes the longshore drift or littoral drift Result of the longshore drift is the continuous transport of sand parallel to the shoreline 16

17 18 Tidal currents In some parts of the world, the tidal range might be several meters in amplitude 17

18 The amplitude does vary through the year as the geometry of the Earth-Sun-Moon system evolves. Amplitude also varies with coastal geometry. Because of the funnelling effect of some estuaries (drowned river valleys), a tidal bore can develop 18

19 If tidal amplitude is greater than wave amplitude, coast and shoreline features can be tide-dominated 19

The Coast: Beaches and Shoreline Processes

The Coast: Beaches and Shoreline Processes 1 2 3 4 5 6 7 8 9 The Coast: es and Shoreline Processes Trujillo & Thurman, Chapter 10 Oceanography 101 Chapter Objectives Recognize the various landforms characteristic of beaches and coastal regions.