CM L3 Flashcards
Methods used to date sites
-Deglaciation events: Time point where ice recedes from landscape
-Volcanic eruptions: Time point where ash is deposited 🪨
How are volcanic eruptions used to date sites?🌋
Eruptions disperse airborne particles across the globe, creating a specific arrangement of rock particles and crystals. These deposit uniformly across the earth surface and are used to calibrate dates between sites
Types of Irish peatlands
-Raised bog
-Atlantic/ lowland blanket bog
-Mountain blanket bog
Characteristics of peatland soils🏜️
-Acidic
- Mor type soils
-Permanently waterlogged
- Anoxic
-Very low biological activity
Poor degradation of organic material leads to peat accumulation;
5m deep (blanket bogs)
10m deep (raised bogs)
Where do raised bogs predominate?
In the midlands, draining down River Shannon and others
Where do lowland blanket bogs dominate?
On the west coast where precipitation is very high even at sea level
Where do mountain blanket bogs develop?
They develop over 250m altitude where rainfall is high. Occurs both west and east coasts.
The plants 🌱that dominate peats include:
-Sphagnum mosses (Acidifiers)
- Ericaceae (Heathers)
- Cyperaceae (Sedges)
- Poaceae (Grasses)
Before blanket bog formation, what happened approximately 10,000 years ago?
The forest became established on the shallow soils that had formed over glacial mineral gravel
What happened approximately 4,500 years ago?
The climate became wetter and cooler. Excessive rainfall began to leach nutrients from topsoil until all highly soluble nutrients were washed away completely
How is an iron pan formed?
Soluble elements in the subsoil (especially iron) binding with anoxic clays form an iron pan. This iron pan is impermeable to both water and plant roots
How did successional sequence occur?
Waterlogging due to the impermeable iron pan provided an ideal habitat for colonization by acid-loving plants.
During the successional sequence, what happens to the habitat
Heathers, sedges, grasses and sphagnum moss take over the habitat and peats begin to form
Sphagnum moss;
Is the K-selected dominant species that controls the growth of bogs
