Vertical Profile of a Route.

Here is a Vertical Profile of a route captured between Knockaclarig and Newmarket Co. Cork.
It contains an amount of interesting data.
The route is just over 20kms. The maximum elevation is 328m. above sea level.
Find out the minimum elevation.
What is the exact elevation after journeying 5km., 10km., 15km.?

Hint: Click on image for a better view !!!!