1. composed of
   1. Sea shells
   2. Dead coral
   3. bones of sea creatures
   4. high calcium carbonate content
2. formed
   1. material
      1. compressed
         1. own weight
         2. sea water
3. Irish limestone
   1. formed
      1. 300 Million YA
      2. 350 Million YA
      3. Ireland
         1. submerged
            1. warm
            2. equatorial
   2. can be seen
      1. tectonic uplift