Q1, How high are the Limestone cliffs at GZ ?
Q2, Is there any marble in the cliffs? Why not?
Q3, From the sign board,What does the Mud contain a huge amount of ?
Limestone is a sedimentary rock composed of calcium carbonate (CaCO3). Most is formed by the accumulation and subsequent solidification of marine fossil debris, but freshwater limestone deposits are also known. Marble formed by the metamorphism of limestone is an important source of calcium carbonate in South Australia, as is shellgrit, an unconsolidated accumulation of sea shell debris found in beach ridge deposits along the coastline.
The main difference between limestone and marble is that limestone is a sedimentary rock, typically composed of calcium carbonate fossils, and marble is a metamorphic rock. Limestone forms when shells, sand, and mud are deposited at the bottom of oceans and lakes and over time solidify into rock. Marble forms when sedimentary limestone is heated and squeezed by natural rock-forming processes so that the grains recrystallize. If you look closely at a limestone, you can usually see fossil fragments (for example, bits of shell) held together by a calcite matrix. Limestone is more porous than marble, because there are small openings between the fossil fragments. Marble is usually light coloured and is composed of crystals of calcite locked together like pieces of a jigsaw puzzle. Marble may contain coloured streaks that are inclusions of non-calcite minerals.
Mangrove sediment:
The sediment around mangrove areas is generally composed of very fine silt or mud particles. These densely packed particles make the sediment very oxygen poor. The only organisms that can survive and thrive in this oxygen free environment are bacteria. The bacteria can reduce sulphur instead of oxygen for respiration giving these environments a very distinct and strong smell of sulphur (rotten eggs). The bacteria on the other hand provide an important first step in the mangrove community food chain. Bacteria are decomposers that break down and convert all dead organic material into useful nutrients that are released into the water. These can ,in turn, be utilised by other organisms in the surrounding water. So even though the sediment in mangrove communities itself does not provide a good habitat for much marine life, the surrounding water can sustain an enormous diversity of organisms.
Mangrove roots
Mangroves actually enhance their own environment, in a way. The root systems are designed to trap silt - the more silt builds up, the more mangroves can grow, and trap more silt and make more muddy areas for more mangroves. But mangroves have had to adapt to all this mud. In terrestrial plants, the soil gets soaked from rain and then dries out, allowing air to reach the roots. This doesn't happen with mangroves as there is little to no oxygen available in the heavy mud, so these plants have adapted their roots to be able to get oxygen without extracting it from the mud. Their roots grow up out of the mud so that oxygen is accessed straight from the air. Many of the root types are distinctive to the species of mangrove so the plant's genus can be identified sometimes by the root type alone.