The Vikings began landing on the Isle of Man in about 850 AD, and ruled the island for nearly two hundred years from 1079. There are many signs still visible of their occupation, including ship burials and Scandinavian carvings, including some runes (see the Braddan church runes, for instance). There may have been Viking landings in this area: there is certainly evidence of their influence in the place names around here.
The coast between Gansey and Castletown is also notable for the great concentration of a rare British bird, the Chough.
To be made aware of the history of the rune stones, it may be wise to read the description for the neighbouring cache.
First stone:
N 54° 05.a0b W 004° 4c.d77
ab: 
cd: 
Second stone:
N 54°04.b9a W 004° 4c.d30
ab: First rune character
cd: Second rune character
The Landing Place is at W 004 4a.bcd , where abcd is from the two rune characters on the second stone.