Thresholds

This elevation on the cat walk at my work is a threshold.

This road in my home town caught my eye as a threshold. One long road
running through the salt marsh. On a larger scale the marsh as a whole can be seen as a
threshold between the ocean and land.

This is the Parker river, a very popular threshold crossed by many people during the day
by bridge or by boat.

These steps give a  gradual elevation into a new threshold.

An entrance into a barn gives either a very tall and narrow, or wide threshold
depending on how much you open the doors.