We tend to repeat customary actions unaware that when we do today what we did yesterday we actually do something different since in the interval both we and our environment have changed; unaware also that we now do without conscious
definition of purpose and method what was done yesterday with specific ends in view and by
relatively precise means.
[Response: Someone may have a more
precise definition but it's basically the
relatively straight part of the glacier (think, «river») below the large, usually more circular catchment area (think «watershed») and the «toe» region (typically an ice shelf for the glaciers in question here).