Surveyors marched inland from the coast for thousands of miles, stopping at increments of as little as a few feet to measure their elevation, and marking each increment with two poles.
测量员从海岸向内陆行进数千英里，每增加几英尺就停下来测量海拔，每增加一英尺就用两根杆子做标记。
2
A level elevationof land along a shore or coast, especially one marking a former shoreline.