Ideas on how to build a rail

we have just built the frame for a forty foot flat rail it is about four feet out of the water and right
when we got it about two feet in the ground then we hit rock. if you have any ideas could u right them down thanks

We have used rebar before to help anchor 2x4's that didn't go in far enough. Get a big hammer and use #6 or bigger bar. Is it solid rock or just rocks? Also so saw a guy one time dig a hole for a 5gal bucket, filled the bucket w/ concrete and the support post on land and then dropped them in the hole and covered them back up. Theres another idea for you. GL