The Giant 's Causeway is an area of about 40,000 interlocking basalt columns , the result of an ancient volcanic eruption . The Giant 's Causeway ( known in Irish as ClochÃ n an Aifir or ClochÃ n na bhFÃ mharach ) is an area of about 40,000 interlocking basalt columns , the result of an ancient volcanic eruption .