Describe how the characteristics of permafrost vary with latitude.

Outline how the seasonal changes taking place in the active layer differ between 50°N and 60°N.

Explain two ways in which the active layer creates challenges for settlement and/or communications in a permafrost area.

“The opportunities for mineral extraction outweigh the challenges in hot, arid areas.” Discuss this statement.

Award [1] for each valid point, including:

• permafrost becomes thicker towards 70°N / the north [1]
• changes from discontinuous to continuous at 60°N [1]
• thin active layer becomes deeper towards the south/50°N [1]
• blocks of permafrost become smaller south of 54/55°north [1].

Maximum [3] if no quantification using depth or latitude.

Award [1] for summer thawing and subsequent refreezing at both, and [1] for recognizing that the active season is much shorter at 60°north / shortens as latitude increases.

In each case, award [1] for each challenge that is identified and [1] for further development/exemplification.

Challenges include:

• the action of solifluction
• thermokarst/subsidence heat from buildings
• heat from pipelines
• changes in vegetation cover
• frost heave
• the weight of vehicles
• keeping cold water flowing to towns
• accessibility of settlements.

For example: The heat from buildings leads to thawing of the active layer [1] causing subsidence of buildings [1].

Areas of mineral extraction include, but are not limited to, oil in the Middle East, diamonds in Botswana/Namibia, uranium in Australia, uranium in Niger, copper in Arizona, copper in the Atacama (Chile).

The opportunities are economic gains from the resources being mined, which provides revenue for the country and for improvement of local infrastructure, eg communications, investment made into local area, eg health care, employment (and higher wages) provided for local people.

Challenges tend to be environmental and include contamination of scarce water resources, effects on local water supply/tables, aesthetic changes in the natural landscape, pollution, accelerated wind/water erosion, economic exploitation by the TNCs (mining companies), little regard for local environment or people; disagreements over land ownership and rights (eg aborigines in Australia), decreased sustainability in the long term.

Good answers should progress beyond simply agreeing with, or rejecting, the statement and discuss the validity of the statement. Another approach might be to provide a structured discussion of different kinds of opportunities and
challenges found in hot, arid areas and arrive at an evidenced conclusion.

At band D, expect a description of some of the challenges and/or opportunities associated with mining in hot, arid areas.

At band E, expect either an explanation of the challenges and opportunities associated with mining in hot, arid areas or a structured discussion of the statement, which may include scale, wealth or power.

At band F, expect both of these elements.

Marks should be allocated according to the markbands.