Photograph 11a.

Oblique aerial photograph of relatively motionless fast ice (on the right) and highly mobile pack ice (in the upper left portion of the picture. Note that cracks are developing in the fast ice as it gradually breaks up in the spring and becomes part of the pack ice.

Photograph 11b.

Oblique aerial photograph of the fast ice along the Alaskan coast of the Chukchi Sea. The southern edge of the pack ice is just visible in the far distance.