eminent author does not think these are man made. Some of these look as though they have suffered much erosion around the edges which cuts into the circular depressions and several are on the top and very precariously it must have been for anyone trying to chip into the rocks as there is little to no room in some places. The top picture also shows a cross on one small boulder. The lower picture shows another group of depressions taken whilst standing on one of the much higher stones.
(left)
I don't know who Maurice H Close 1928 was but have included it in anycase.