Limestone: What is limestone? Limestone is a sedimentary rock widely distributed in New Zealand. The rock is more than 50% calcium carbonate (CaCO3) derived from the shells of tiny marine fossils. Limestone typically forms in shallow marine waters from an accumulation of fossils of marine organisms. In the Waikato there are two large quarries where limestone is formed, one at Te Kuiti and another at Otorohanga, near where the Waitomo Caves are located. In this report, I will study and analyze the chemical processes involved in the formation of limestone caves, as well as the consequences these chemical processes have on the environment. Limestone Formation: In New Zealand, most limestones consist of shell fragments and lime muds that were originally deposited in shallow marine waters. These fragments are loose sediments that undergo diagenesis to form a hard limestone sedimentary rock. Loose sediments are buried beneath the ground, putting great pressure on the calcium carbonate sediments. This application of pressure is called pressure dissolution. Thanks to this pressure, the calcium carbonate begins to dissolve. It then seeps into the pores and reprecipitates as cement, which imparts the solid characteristics of limestone. Limestone Cave Formation: Limestone forms when carbonic acid reacts with limestone bedrock. However, we must first look at how this carbonic acid was formed: Co2 + H2O H2CO3. The word for this equation is Carbon Dioxide + Water Carbonic Acid. This reaction occurs when evaporated water combines with carbon dioxide in the atmosphere to produce carbonic acid. Include soil Co2. The carbonic acid found in the middle of the paper......in the atmosphere of the cave. The air we breathe contains carbon dioxide, so Waitomo Cave's decision to limit the number of visitors to certain caves each day is a great way to reduce the impact on the balance. (http://books.google.co.nz/books?id=IBESYmQcb0sC&pg=PA119&lpg=PA119&dq=chemical+equilibrium+in+caves&source=bl&ots=XQ9_hSQ5GP&sig=0i8oZ2ZIAyqHOSKd9R2wr3yo7_I&hl=en&sa=X&ei=gLB4U53tMbKp 7 AbSwIGQBA&ved=0CCcQ6AEwAA#v=onepage&q= chemical %20equilibrium%20in%20caves&f=false)Another impact on the caves is the numerous road and agricultural works aimed at producing an urban lifestyle. Water plays an important role in the formation process of caves and mineral crystallites. Thanks to toxic chemicals produced by urbanization, this water is contaminated and poses a threat to the continuity of the caves. (http://www2.nature.nps.gov/views/KCs/CaveKarst/HTML/ET_Threats.htm)