Geography · 12th Grade · Physical Systems and Climate Dynamics · Weeks 10-18

Glacial and Periglacial Landscapes

Examining the impact of ice on Earth's surface, past and present, and its role in climate change.

• Common Core State Standards
• C3: D2.Geo.4.9-12
• C3: D2.Geo.6.9-12

About This Topic

Glaciers and ice sheets have shaped much of the landscape that students in northern states live in today -- the Great Lakes, the prairie pothole region of Minnesota and the Dakotas, the U-shaped valleys of the Rockies and Sierra Nevada, and the boulder-strewn terrain of New England all reflect the work of Pleistocene ice. For 12th grade geography students, this topic connects past physical processes to present landscapes, and present glacial retreat to future geographic impacts from sea level rise to freshwater supply disruption.

Understanding glacial and periglacial processes requires thinking across very different timescales -- from the tens of thousands of years over which continental ice sheets advanced and retreated, to the decades-scale mountain glacier retreat that is currently accelerating. This temporal range challenges students to reason from evidence for events they cannot observe directly and to project future changes from current trends.

Active learning is especially effective here because students need to reason from landforms and proxy data. When they match landform photographs to glacial processes, analyze ice core and pollen records as evidence of past climates, or map the extent of the last glacial maximum and compare it to the present, they practice inferential scientific reasoning skills that transfer broadly to climate science.

Key Questions

1. Explain how glacial processes shape distinctive landforms.
2. Analyze the evidence for past glaciations and their influence on current landscapes.
3. Predict the future geographic impacts of melting glaciers and permafrost.

Learning Objectives

• Analyze glacial landforms such as moraines, drumlins, and fjords, classifying them by their depositional or erosional origin.
• Compare and contrast the processes of glacial abrasion and plucking, explaining how each contributes to landscape modification.
• Evaluate the evidence presented in ice cores and pollen records to reconstruct past glacial extents and associated climate conditions.
• Synthesize information from maps and data to predict the potential geographic impacts of current glacial and permafrost melt on coastal regions and freshwater availability.
• Explain the mechanisms driving periglacial processes like freeze-thaw cycles and solifluction, and identify resulting landforms.

Before You Start

Plate Tectonics and Landform Development

Why: Students need a foundational understanding of how geological forces shape Earth's surface to comprehend glacial erosion and deposition.

Climate Zones and Factors

Why: Understanding the conditions necessary for glaciation, such as temperature and precipitation, is crucial for analyzing past and present glacial landscapes.

Key Vocabulary

Glacial Till	Unsorted and unstratified sediment deposited directly by glacial ice, often forming features like moraines.
Fjord	A long, narrow inlet with steep sides or cliffs, created by glacial erosion and subsequently flooded by the sea.
Permafrost	Ground (soil, rock, or sediment) that remains frozen for two or more consecutive years, underlying much of the Arctic and alpine regions.
Drumlin	An elongated hill formed by glacial ice acting on underlying unconsolidated till or bedrock, streamlined in the direction of ice flow.
Solifluction	The slow downslope movement of soil and weathered debris over permafrost, particularly during periods of thaw.

Watch Out for These Misconceptions

Common Misconception

Glaciers only exist in polar regions.

What to Teach Instead

While polar ice sheets are the largest glacial systems, mountain glaciers occur on every continent and at tropical latitudes where elevations are high enough. Many major rivers -- including those feeding hundreds of millions of people in South Asia -- depend on mountain glacier meltwater. Students examining global glacier distribution maps are often surprised by tropical glaciers in Africa, South America, and Southeast Asia.

Common Misconception

The ice ages are ancient history with no relevance to current landscapes.

What to Teach Instead

Much of the landscape in the northern US was shaped by Pleistocene glaciation that ended only about 10,000-12,000 years ago. The Great Lakes, thousands of Minnesota lakes, Long Island's shape, and much of the Midwest's agricultural soil all reflect glacial legacy. Students mapping these features in their own region build direct personal connection to glacial geography that makes the topic immediate rather than remote.

Common Misconception

Permafrost is just permanently frozen ground with no significant geographic consequences.

What to Teach Instead

Permafrost underlies about a quarter of the Northern Hemisphere's land surface and plays a critical role in carbon storage, infrastructure stability, and hydrology. As it thaws, it releases stored organic carbon -- a significant climate feedback -- and destabilizes roads, buildings, and pipelines in Arctic communities. Students tracking permafrost thaw impacts in Alaska and Siberia quickly see that it is far from trivial.

Active Learning Ideas

Inquiry Circle: Landform Identification Challenge

Groups receive unlabeled photographs of glacial and periglacial landforms -- cirques, moraines, drumlins, eskers, kettle lakes, solifluction lobes. Using process descriptions, they match each landform to the glacial process that created it and identify the approximate geographic regions where similar features are found today.

45 min·Small Groups

Gallery Walk: Evidence for Past Glaciations

Stations present different types of proxy evidence for past glaciations -- glacier striations on bedrock, erratic boulders, glacial lake sediment records, ice core data, pollen diagrams. Students annotate each station with what the evidence type tells us, what it cannot tell us, and one remaining question it raises.

35 min·Whole Class

Think-Pair-Share: Where Will the Water Go?

Students examine current data on mountain glacier mass balance trends and regional sea level projections. Pairs estimate the volume of meltwater a specific glacial system contributes and predict the geographic consequences for coastal communities and downstream water supplies before comparing reasoning with the class.

30 min·Pairs

Case Study Analysis: A Landscape That Ice Made

Each small group investigates a specific US region shaped by glaciation -- the Great Lakes basin, the Finger Lakes, Cape Cod, or the Palouse Hills. They explain which glacial processes produced the landscape, what economic activities depend on glacially produced features, and how ongoing glacial retreat or permafrost thaw might change the region's geography.

50 min·Small Groups

Real-World Connections

• Geologists and environmental scientists study glacial retreat in the Himalayas to assess risks to downstream communities in India and China from glacial lake outburst floods.
• Engineers designing infrastructure in Alaska and Siberia must account for the challenges of building on permafrost, which can thaw and destabilize foundations as temperatures rise.
• Urban planners in coastal cities like Boston and Seattle are analyzing projections of sea level rise, directly linked to melting ice sheets in Greenland and Antarctica, to inform long-term development strategies.

Assessment Ideas

Quick Check

Provide students with a set of 5-7 photographs of different landforms. Ask them to label each landform (e.g., U-shaped valley, moraine, esker) and briefly describe the primary glacial process that created it.

Discussion Prompt

Pose the question: 'Imagine you are advising a government on climate change adaptation. What are two critical geographic impacts of melting glaciers and permafrost that require immediate attention, and why?' Facilitate a class discussion where students share their reasoning.

Exit Ticket

On an index card, have students define 'permafrost' in their own words and then list one specific challenge associated with its thawing for human settlements or ecosystems.

Frequently Asked Questions

How do geographers know where glaciers were thousands of years ago?

Multiple lines of physical evidence record past glacial extent: terminal and lateral moraines mark the outer limits of ice advance; erratic boulders were transported far from their source bedrock; glacially scoured bedrock preserves striations indicating ice flow direction; and sediment cores from glacial lakes record cycles of glacial and interglacial deposition. Together these allow geographers to reconstruct glacial extent and timing with considerable precision.

What is periglacial geography and how is it different from glacial geography?

Periglacial environments are those adjacent to glaciers or at high latitudes and altitudes where freeze-thaw cycles dominate landscape processes even without permanent ice cover. Features like solifluction lobes, patterned ground, and thermokarst depressions form through repeated freezing and thawing of soil moisture. Today, periglacial processes are active across large portions of the Arctic and subarctic as permafrost thaws at accelerating rates.

Why are retreating mountain glaciers a water security concern for downstream communities?

Many rivers in arid mountain regions receive a significant portion of their summer flow from glacier meltwater, which supplements declining snowpack during dry seasons. As glaciers retreat, meltwater initially increases as more ice melts, but will eventually decrease as glacial mass is depleted -- leaving downstream communities without the seasonal water buffer they depend on. Western US rivers and South Asian glacial systems are among the most affected globally.

How does active learning help students reason about processes they cannot directly observe?

Glacial processes operate over timescales of thousands to tens of thousands of years, making direct observation impossible. Active learning that asks students to reason backward from landforms to processes, or forward from current trends to future impacts, builds the inferential reasoning that physical geography demands. Students who practice this reasoning with real data -- rather than reading about conclusions -- develop the habit of treating landscape as evidence.