We know these grooves are caused by icebergs and not by glaciers because they move in a wide variety of directions. The glaciers tended to move in one general direction. Sometimes we have to change our direction because of all the ice in our path. There are several types of ice in Antarctica. Most of what we are seeing is called pack ice.
Pack ice is made up of various sizes of ice pieces that are floating with the currents.
Loose or open pack is when the pieces of ice are spread apart with water between them. Close pack is when the pieces of ice are pretty close together and you can't see much water at all. Pack ice can be found around the continent of Antarctica at all times of the year. Sea ice is the name given to all the ice that freezes from the sea water. It can grow to a thickness of many feet.