Following Sian's and Jane's helpful comments I added oil tanks to the low tide felt (as on left below) and I think the textures and sewing will make them better linked, I shall also modify the hill line to provide flow.
I dyed/ painted some scrim to the sea and boulder colours and the tissue silk I had ordered arrived so I made another piece of felt to experiment with embellishment - I laid threads, knitted wool and textiles down amongst the wool roving to see which complemented them best and gave the appearance i wanted and actually bonded in the felting.
The thick cottons did not embellish , the wools were fine
Textiles- the tissue silk and scrim both worked well and felted. The sari silk did not felt- perhaps it was not silk-. I knitted some of the grey hurunui roving and merino together and cut the knitted piece up to make rocks , boulders. This was successful. I used different threads- cotton silk and rayon to decorate/ embellish further. I was aiming for appearance of moving water. This sample looks very busy, the larger, final pieces will not be as busy as the sample shows stitching for both pieces, the top part of the blue sea is the calm sea and middle the grey day, wind roughed sea. It was easier for me to make a single piece of felt to sample.