The visual stratigraphy of the ice
Glacier ice contains visible layers called cloudy bands. Especially in the relatively dirty glacial ice, the layers are related to the content of dust and other impurities and can be used for dating purposes.
The layers are not clearly visible in the freshly drilled ice core, as the core surface is scratched by the cutters. To record the visible layering, or the visual stratigraphy, a special tool called a line scanner is used on a section of the ice core that has been polished.
In the line scanner, a camera above the ice slab and a light source underneath the core are moved synchronously along the ice core.
Light is focused by the lenses and crosses the ice at a 45° angle relative to the ice surface. If there are no impurities in the ice, the light passes through the ice and does not reach the camera. These areas appear black on the image. When light is scattered by cloudy bands, bubbles, and impurities, the camera records these layers as white or grey areas.
Ice Core Drilling Projects