How Shields Are Formed

Shield form over the years through processes such as plate tectonics, erosion and glaciations. Plate tectonics refers to the movement and collision of the Earth’s outer crust. When these crustal plates collide they may weld together, forming larger landmasses.

What are shields in geology?

A shield is a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas. These rocks are older than 570 million years and sometimes date back 2 to 3.5 billion years.

What tectonic province forms the shield?

The continental crust that had been assembled by about 2.6 billion years ago soon began to break up into continental fragments. The largest of these fragments forms the Superior province, which is located in the south-central part of the Canadian Shield and is some 1,500 miles (2,400 km) wide.