Limestone

What are the limestone features?

-Clints and grykes -Surface depression -Cockpits -Swallow holes

What are the characteristics of limestone?

-Structured in horizontal beds of rock, separated by horizontal bedding planes and joints at right angles. -Limestone is pervious,but not porous, water doesn't pass through the actual rock, but it does pass down joints. -Calcium carbonate is soluble. -Carboniferous limestone is a sedimentary rock made of calcium carbonate. It is generally light-grey in colour, and is hard. -Carboniferous limestone has horizontal layers (beds) with bedding planes, and vertical joints. These joints are weakness in the rock which are exploited by agents of both denudation and weathering. Water seeps through the joints in the limestone.

Cave

A cave is a natural opening in the rock which is large enough to be entered by a person and extends to points where daylight doesn't penetrate. Underground rivers dissolve the limestone and carry it away to leave these passageways which can be full of water during periods of heavy rainfall.

cave system

A cave or caves with a complex network made up of interconnected chambers and passages that make up an underground drainage system.

Stalactite

A stalsctite is a calcium carbonate deposit like an icicle formed in cave by chemical precipetation from drips or thin filns of water. They hang from the ceiling and are built up from successive growth layers and almost always have pointed tips.

How are stalactites formed?

As a drop of water hangs from the ceiling, it loses some of its carbon dioxide making it less acidic this means that it can't hold all of the dissolved minerals that it had picked up on its way throung the cracks above. The drop leaves a few crystals of the mineral calcite behind and a stalactite begins to grow over hundreds and thousands of years.

What is the chemical equation for carbonation?

CaCO3+H2CO3=Ca(HCO3)2 Calcium carbonate (limestone)+Carbonic acid= Calcium bicarbonate.

Where are limestone formed?

Most limestones are formed in shallow, calm, warm marine waters.This type of environment is where organisms capable of forming calcium carbonate shells and skeletons can easily extract the needed ingredients from ocean water. When these animals die their shell and skeletal debris accumulate as a sediment that might be lifted into limestone.

Swallow hole

Surface and rainwater do not flow far on exposed limestone but infiltrate rapidly into the rock and soil. Where a joint or intersection of joints has been greatly weathered or dissolved, water can pass down through the limestone. These joints become enlarged because of carbonation and form swallow holes. These holes then allow rivers to pass underground. Sometimes they are large enough to form steep sided depressions.

Column

When a stalactite and a stalagmite grow so much that they join together to form a vertical limestone pillar from floor to ceiling

Clints and Grykes

When rain falls on limestone, carbonation in weaker joints and cracks cause pitting an wearing of the surface into grooves, leaving small ridges in between. These ridges are clints and the worn areas are the grykes. In the Caribbean, exposed limestone is often pitted and grooved by this process for example Northern Barbados.

What is a limestone pavement

bare limestone rock surfaces composed of slabs of rock (clints) separated by variable-width vertical cracks (grykes). These grykes have developed by weathering and enhanced solution along joints. Composed principally of calcite, limestone is vulnerable to chemical weathering by water (solution) and dissolves easily in the Yorkshire dales exposure of very extensive pavements may be partly an example of the stripping of soil by moving ice during the last glaciation period more than 10,000 years ago.

What is a bedding plane?

layers of limestone that contain vertical cracks and joints. Joints and bedding planes make the rock permeable.

What is limestone?

organic sedimentary rock, meaning it was formed from the remains of tiny sea shells and micro-skeletons deposited on the sea. Limestone is made up of calcium carbonate and reacts with HCL.

Cockpits and conical hills

they are formed when limestone has a criss cross pattern of joints. The rock nearest to the joints is dissolved fastest, because this is where water collects. A deep star-shaped depression is formed where two joints meet small conical hills remain away from the joints Where the jointing is regular the hills are arranged in rows.

Stalagmites

when water containing dissolved limestone falls to the floor of a cave some of the calcite precipitates out. This build up of deposit forms a mound growing up from the floor called a stalagmite. The shape of the stalagmite is largely determined by the drip rate, ceiling height, cave atmosphere conditions and the carbonate chemistry of the drip water solution.