Some well-known columnar basalt is in Ireland, Iceland, and the Devil's Postpile monument in California (and obviously, Penghu). The Giants Causeway in Northern Ireland is another very popular and famous columnar basalt! They usually form in cliffs that descend into the sea, as well as in the deep sea!
Many areas with columnar basalt are protected and it is prohibited to do such activities in or around the area! Penghu has a columnar basalt nature reserve, which consists of many islands, and is a great place to visit if you want to see abundant columnar basalt!
Development and building activities in the areas where there is columnar basalt can endanger it's preservation. If building operations take place around columnar basalt, it could cause the basalt to fall apart and be destroyed.
