They have to maintain those claims. Every year they have to submit reports or pay money in lieu of doing work for the same dollar value. Teck already has sufficient claims that would take them decades to explore and prove up. At some point they might as well sit tight and let the claims, say under the glacier, wait for a generation.

Although moving glaciers to get at gold is apparently an option:

"Canadian international mining company Barrick Gold has plans to relocate three glaciers in the mountain range between Argentina and Chile to gain access to 17.6 million oz. of rich gold and silver deposits.

Chilean farmers and residents of the surrounding Huasco Valley are strongly opposed to the proposal of transferring the ice masses. The glaciers' tributaries are used for irrigation by the farmers, and their removal would threaten the ecological balance and agricultural production of the fertile river valley.

Barrick hopes to transfer 300,000 cubic meters of ice with a 20-hectare surface area from the glaciers that surround the deposits. To mitigate ecological impact and prevent ice from melting, Barrick hopes to transfer the three glaciers, Toro I, Toro II and Esperanza, to an area with similar surface characteristics and elevation by merging the three into a larger glacier, Guanaco, located several kilometers south with a surface area of over 200 hectares.

The company's detailed plan to move the glaciers will be presented to the Regional Environmental Commission (COREMA) in the coming months, according to Rodrigo Rivas, Barrick's communications manager."--http://quebec.indymedia.org/en/node/23599