Geology and Sea Level - Edexcel A-Level Geography

Flashcards covering weathering processes, mass movement, sea level changes, coastline types, and sand dune succession for A-Level Geography.

What is the difference between mechanical, chemical, and biological weathering?

Mechanical weathering physically shatters rock (e.g., freeze-thaw); chemical weathering involves a chemical reaction that dissolves or crumbles rock (e.g., carbonation); and biological weathering involves living organisms like plant roots or rock borers.

How does freeze-thaw weathering cause rock to shatter?

Water enters cracks, freezes, and expands by $9\%$, exerting outward pressure on the rock.

Where is salt crystallisation most common and how does it work?

It is common in the "splash zone" where seawater evaporates in rock pores, leaving salt crystals that grow and exert pressure.

What is the chemical process of carbonation in weathering?

Rainwater absorbs $\text{CO}_2$ to form weak carbonic acid, which reacts with calcium carbonate in Limestone or Chalk to dissolve the rock.

What is oxidation in the context of sub-aerial processes?

Oxygen reacts with iron minerals in rock (similar to "rusting"), causing the rock to crumble.

What are two examples of biological weathering listed in the notes?

Plant roots prying rock apart and rock borers like Molluscs (Piddocks) or urchins drilling into rock.

What characterizes rotational slumping and where is it commonly found?

Material moves down a curved slip plane, often in clay environments like Holderness when pore water pressure is high; it creates a "stepped" cliff profile.

What is the difference between a landslide and a mudflow?

A landslide is rapid movement down a flat or linear slip plane, whereas a mudflow involves saturated fine-grained sediment flowing like a liquid.

What results from a rockfall at the base of a cliff?

The rapid falling of fragments forms a talus slope.

What is the difference between Eustatic and Isostatic change?

Eustatic change is a global change in ocean water volume (e.g., melting ice), while Isostatic change is a local change in the level of the land (e.g., post-glacial rebound).

How does the UK's land level currently vary due to isostatic factors?

The North and West are rising (rebounding), while the South and East are sinking (tilting down).

What are two landform examples of an emergent coastline?

Raised beaches (former beaches stranded above high tide) and relict cliffs (ancient inland cliffs).

What is the difference between a Ria and a Fjord?

A Ria is a drowned V-shaped river valley, while a Fjord is a drowned U-shaped glacial valley.

What is a Dalmatian Coast?

A submergent coastline where valleys parallel to the coast are flooded, leaving a chain of offshore islands.

How does a Discordant (Atlantic Type) coastline differ from a Concordant (Pacific Type) coastline?

Discordant layers run perpendicular to the coast, forming headlands and bays; Concordant layers run parallel, usually forming a straight coastline unless breached to form coves.

What are the three physical requirements for sand dune formation?

A large supply of sand, a large tidal range to dry the sand, and an onshore wind.

What are Fore/Yellow dunes and what species is crucial to them?

Dunes where pioneer species like Marram Grass stabilize the sand with long roots; they are called yellow due to the presence of bare sand.

How do Grey Dunes differ from Yellow Dunes?

They contain more humus (organic matter) from dead grass, making them grey and more soil-like, supporting more plants like gorse and heather.

What are dune slacks?

Depressions between dunes where the water table is reached, allowing moisture-loving plants to grow.

What is the climax community of a psammosere?

The final stage of plant succession where soil is rich enough to support Oak or Pine woodland.