Welcome to Glaciated Landscapes!
Hello there! Welcome to your study notes for the Glaciated Landscapes and Change chapter. Whether you’re a geography enthusiast or someone who thinks "it’s just a big block of ice," this guide is for you. We are going to explore how ice has sculpted our world, why the climate changes, and how these fragile environments are managed today. Don’t worry if some of the terms seem like a mouthful at first—we’ll break them down together!
Why is this important? Glaciers aren't just pretty to look at; they are "nature’s bulldozers." They provide water for millions and tell the story of our planet's past. Understanding them helps us predict our future in a warming world.
EQ1: How has climate change influenced the formation of glaciated landscapes over time?
The Big Timeline: From the Pleistocene to the Anthropocene
The Earth’s climate is like a giant pendulum, swinging between cold Glacials (ice ages) and warmer Interglacials (like the one we are in now).
• Pleistocene: This era started about 2.5 million years ago. It was the time of the great ice sheets.
• Holocene: This is our current interglacial period, which started about 11,500 years ago.
• Anthropocene: A new term used to describe the current period where human activity is the main driver of climate change.
Why does the climate change?
Nature has its own ways of "flipping the switch" on the global thermostat:
1. Milankovitch Cycles: These are long-term changes in the Earth's orbit. Think of it like a spinning top that wobbles. Sometimes we are tilted further from the sun, or our orbit becomes more oval, leading to colder periods.
2. Solar Output: The sun doesn't always shine with the same intensity. Sunspots can cause slight variations in heat.
3. Volcanic Eruptions: Massive eruptions blast ash into the atmosphere, which reflects sunlight away, cooling the Earth.
4. Atmospheric Gases: The amount of \(CO_2\) and methane traps heat. More gas = warmer planet.
Did you know? During the last glacial maximum, the ice over parts of the UK was over 1km thick! That's like stacking three Empire State Buildings on top of each other.
The Cryosphere and Periglacial Landscapes
The Cryosphere is just a fancy name for all the frozen water on Earth. This includes Ice Sheets (huge masses like Antarctica), Valley Glaciers (rivers of ice), and Ice Caps.
Periglacial means "around the ice." These are areas that aren't covered by glaciers but are freezing cold. The ground here is Permafrost (permanently frozen ground).
Key processes in these areas:
• Nivation: Erosion under a snow patch.
• Frost Heave: Freezing water in the soil expands, pushing stones to the surface in Patterned Ground.
• Solifluction: In summer, the top layer of soil thaws and slides over the frozen layer below like thick porridge.
• Pingos: Massive ice-cored mounds that look like small hills.
Quick Review: Climate changes due to Earth's orbit (Milankovitch) and gases. Periglacial areas are "ice-adjacent" and shaped by freezing and thawing.
EQ2: What processes operate within glacier systems?
The Glacier as a Bank Account: Mass Balance
Think of a glacier like a bank account.
• Accumulation (Deposits): Snow falling and avalanches adding ice.
• Ablation (Withdrawals): Melting, evaporation, and Calving (ice chunks breaking off into the sea).
The Glacial Mass Balance is the difference between the two:
\( \text{Net Balance} = \text{Accumulation} - \text{Ablation} \)
If Accumulation is higher, the glacier grows (Positive Balance). If Ablation is higher, it shrinks (Negative Balance).
How do Glaciers Move?
Don’t worry if this seems tricky; ice is actually more "bendy" than you think!
1. Basal Slip: Meltwater at the bottom of the glacier acts like grease on a slide, letting the ice slip over the rock. This happens in Temperate (warmer) glaciers.
2. Internal Deformation: In Polar (very cold) glaciers, the ice is frozen to the rock. It moves by individual ice crystals sliding over each other, like a deck of cards being pushed.
3. Regelation Creep: Ice melts when it hits an obstacle (due to pressure) and refreezes on the other side.
Mnemonic Aid: To remember movement types, think "B.I.R." — Basal slip, Internal deformation, Regelation.
Key Takeaway: Glaciers grow when "income" (snow) beats "spending" (melt). They move by sliding on water or by the ice crystals shifting internally.
EQ3: How do glacial processes create landforms?
Erosion: Nature’s Sandpaper and Crowbar
Glaciers erode the land in two main ways:
• Plucking: Meltwater freezes onto the rock and the moving glacier "plucks" chunks of rock away. It’s like freezing your tongue to a lamppost and then trying to walk away (ouch!).
• Abrasion: The rocks trapped in the ice rub against the bedrock like sandpaper, leaving scratches called Striations.
Sculpting the Uplands (Erosional Landforms)
• Corries (or Cirques): Armchair-shaped hollows where the glacier starts.
• Arêtes: Knife-edged ridges between two corries.
• Pyramidal Peaks: When three or more corries erode back-to-back (e.g., the Matterhorn).
• Glacial Troughs: U-shaped valleys carved from old V-shaped river valleys.
• Roches Moutonnées: Rock bumps that are smooth on one side (abrasion) and jagged on the other (plucking).
Leaving it Behind (Depositional Landforms)
When the ice melts, it drops everything it was carrying. This unsorted "jumble" of rocks and clay is called Till.
• Moraines: Ridges of till. Lateral (at the sides), Medial (in the middle), and Terminal (at the very end).
• Drumlins: Egg-shaped hills that show the direction of ice flow.
• Erratics: Large boulders "dropped" in an area where the geology is completely different. They look like they don't belong!
Meltwater: Fluvioglacial Landforms
As glaciers melt, water flows over (supraglacial), inside (englacial), and under (subglacial) the ice. This water sorts the sediment by size (unlike till).
• Eskers: Long, winding ridges of sand and gravel—old tunnels under the ice.
• Kames: Mounds of sediment.
• Sandurs (Outwash Plains): Flat areas in front of the glacier where meltwater spreads out.
Quick Review: Erosion plucks and scrapes. Deposition leaves till. Meltwater creates "fluvioglacial" features that are sorted and layered.
EQ4: How are glaciated landscapes used and managed today?
Why do we care about these landscapes?
Glaciated areas have intrinsic value (meaning they are important just because they exist).
• Economic: Tourism (skiing, hiking), Hydroelectric Power (water from melting ice), and Mining.
• Environmental: They are home to unique Biodiversity (like the Tundra) and are vital for the water cycle.
The Threats
These are fragile environments.
• Natural Hazards: Avalanches and Glacial Outburst Floods (Jökulhlaups).
• Human Impact: Over-tourism can lead to soil erosion and "trampling" of rare plants. Climate change is the biggest threat, causing glaciers to vanish.
• Case Study Tip: Think about the Himalayan Glaciers. As they melt, water supplies for millions of people are at risk.
Managing the Ice
Management involves different Players (stakeholders):
• Conservationists: Want to protect the land (e.g., National Parks like Yosemite).
• Local Governments: Balance money from tourism with protection.
• TNCs (Transnational Corporations): May want to exploit resources through mining or forestry.
Strategies range from total Preservation (leaving it alone) to Sustainable Management (using it in a way that doesn't ruin it for the future).
Common Mistake to Avoid: Don't confuse "relict" and "active." Relict landscapes were shaped by ice in the past but have no ice now (like the Lake District). Active landscapes still have glaciers today (like Greenland).
Key Takeaway: Humans use glaciated areas for money and beauty, but our actions (especially climate change) make managing these fragile places very difficult.
You’ve reached the end of the notes! Take a deep breath. Glaciated landscapes are complex, but by focusing on the "Bank Account" of mass balance and the "Sandpaper" of erosion, you've got the core ideas down. Good luck with your revision!