What type of rock is limestone? describe how a limestone rock is likely to change over time

Limestone is a type of sedimentary rock

Limestone is a type of sedimentary rock which is composed mainly of skeletal parts of organisms living in water such as coral, forams and molluscs. The major materials of limestone are the minerals such as calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Limestone can turn into the metamorphic rock called marble if the right conditions occur.

Over time limestone can be deformed and crystallized

Limestone and chalk are mostly made up of calcium carbonate. When acidic rainwater falls on limestone or chalk, these rocks may react with the rainwater, causing the rock to be weathered. With the passage of time if limestone has been squeezed and reshaped by temperature and pressure, its structure and composition changes to form a recrystallised limestone which is called  marble.

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.