Complex sentence: Very near to the village, there is "Kirkjugólf" to be seen, the so-called church pavement of "basalt" These are basalt columns in the earth, only the top can be seen.
Split into simpler sentences: Very near to the village, there is "Kirkjugólf", the so-called church pavement of basalt. It is consisting of basalt columns in the earth, only the top can be seen.