Dictionary:Turning point, turn point (TP)
1. The location of the survey rod in the procedure where transit and survey rod successively leap-frog over each other in traversing along a line. The point on which a foresight is taken from one instrument station in a line of survey and on which a backsight is taken from the next instrument station. 2. A point on maximum-depth-estimation curves at which limiting depths reach a minimum; an aid in gravity interpretation. 3. The deepest point on a diving wave (q.v.).