At http://malagabay.wordpress.com/2013/11/04/liesegang-rings-5-geological-q… … Tin Cullen gets more and more interesting as he probes down through the uniformitarian minefield of geology. Silicates, according to the consensus view of the late 19th/ early 20th centuries, were thought to have had a gelatinous stage before ripening to become agates, and this involved liesegang rings. Nowadays, geological theory contends that the agate ring patterns are formed by deposition of layers (over a long period of time) – see also www.minerals.net/mineral/agate.aspx and www.horo-achate.de/seiten_englisch/index_eng.html
Silica gel is also a preferred medium for growing crystals. Silicaon is the hightly reactive element that dominates the mineral kingdom. Its negative ions combine with metallic positive ions, such as those of potassium and magnesium, to form the mixtures of salts that contribute to many soils, clays, and rock formations. Although natural specimens of gelatinous silica are rarely encountered the same cannot be said for sand because the hydrogel form of sand is more commonly known as quicksand.
Quicksand forms in saturated loose sand when water in the sand cannot escape. As such, it can form in standing water or in upwards flowing water (as from an artesian spring). It is easy to envisage the optimal laboratory condition for the development of liesegang rings occurring naturally when quicksand dehydrates and starts to form sandstone. This geological common formation tends to form in discrete blocks and sperical shapes, or concretions (as they are described), an ideal closed system for liesegang rings. Concretions form within layers of sedimentary strata that have already been deposited. They usually occur early in the burial history of the sediments, before the sediment actually becomes hardened rock (and Malaga Bay provides a series of images to outline this point). He also makes the point mainstream geology is reluctant to actually mention quicksand hydrogel. Other geologists even go so far as to say liesegang rings form after the rock itself has formed -which is not possible according to Cullen. He also says there are three questions many geologists would avoid – i) where did the sand in the Sahara come from? ii) where did the sand in sandstone come from? and iii) where did the water on Earth come from? This is because the liesegang rings found in sandstones suggest that sandstone primarily formed from the hydrogel called quicksand. The vast quantities of sandstone in the world strongly suggests vast quantities of precursor sandstone, and the vast quantities of precursor quicksand strongly suggests vast quantities of silica rich 'upwards flowing water' from within the Earth. This is of course all part of the Expanding Earth hypothesis – and makes a good argument. It is also essentially critical of mainstream geological theories, and rather intriguing for something found by sheer accident, liesegang rings, to provide a means with which to cast doubt on the uniformitarian model. Such is life.
One can transfer these ideas to look again at local geology. For example, those huge sarsen (sandstone) blocks, in strange shapes, at the Avebury megalithic complex, or the large lumps of sandstone dug out of the clays that fill depressions at the top of the Chilterns plateau, in uncertain relationship to the chalk bedrock and the various clays of the fill. Cullen provides the example of Sydney in Australia, which sits on 6km of sandstone and shale. It is composed of very fine silica grains and a small amount of the iron mineral siderite, in varying proportions, bound with a clay matrix.
Liesegang phenomena in the laboratory is often connected with the formation of crystals. This is replicated in nature – in rocks. Quartz very often contains tiny crystals. However, mainstream geology fails to make the connection and this is done by pointing to the way materials are often found trapped inside another mineral, known as inclusions. Geology doesn't associate inclusions with liesegang phenomena because fragments included in rock are often older than the rock they are within – for example fragments of rock caught up in a lava flow, or insects caught by amber. Cullen says that this view may not be universally true, at least so far as crystals are concerned. He provides some images of gemstone that contain typical liesegang helices.