Depositional Landforms - Saltmarshes

Question 1

What are mudflats?

Answer 1

• at the edges of estuaries are low energy environments with deposition of fine sediment
• commonly found in river estuaries and in sheltered areas as behind a spit
• deposition is so prevalent in an estuary because of the interaction of the sea and river - both carry lots of fine sediment (clay and silt)

Question 2

What is flocculation?

Answer 2

• interaction of the salt and fresh water encourages flocculation to occur
• as river freshwater (carrying high quantities of sediment) meets salt water, the salt within the ocean will have an electrostatic effect upon the clay particles. This causes the particles to “clump” together, become heavier and be deposited on the mudflat

Question 3

Development of Saltmarsh - Halosere Succession

Answer 3

• low-lying vegetation, such as eelgrass and algae, may begin to grow on the mudflats. This slows down the current further and leads to more deposition
• pioneers begin to colonise the area. These plants are able to tolerate high levels of salt and periodic submergence at high tide.
• pioneers then succeeded by other plants, such as sea asters and sea lavender. These form a dense mat of vegetation up to 15cm high.
• dead organic matter helps to build up the surface, which grows in height at up to 25mm per year, while also improving soil fertility
• as the height of the marsh rises, complex creek systems develop which channel the tides and these get deeper as the marsh gets higher
• as the land rises above sea level, rushes and reeds become established as rainwater washes salt out of the soil. Eventually this will develop into a climax community of shrubs and trees.