Fossil hunting is a fascinating pastime enjoyed by families and people of all ages and levels of expertise throughout the year. With just just a little time spent studying the basics anybody can benefit from the thrill of discovering evidence of prehistoric creatures and the environments they lived in. The following web page gives some steerage to getting began, including the very best places to look and techniques for fossil hunting effectively and safely.
The trendy use of the word ‘fossil’ refers to the physical evidence of prehistoric life that's preserved from a time period previous to recorded human history. There is no such thing as a universally agreed age at which the evidence may be termed fossilised, however it’s broadly understood to encompass anything more than a few thousand years. Such a definition consists of our prehistoric human ancestry and the ice age fauna as well as more historic fossil teams such as the dinosaurs, ammonites and trilobites.
Fossils happen commonly world wide although just a small proportion of former life made it into the fossil report, maybe less than a billionth. Most living organisms merely decayed without trace after death. Thus, the abundance of fossils displays the immense number of organisms which have lived and the huge length of time over which the rocks have accumulated.
The earliest fossils discovered date from 3.5 billion years ago, nevertheless it wasn’t till roughly 600 million years ago that complicated multicellular life began to enter the fossil document, and for the purposes of fossil hunting the vast majority of effort is directed towards fossils of this age and more recent.
The geologic timescale is divided into eras which are additional divided into intervals, of which essentially the most incessantly quoted is the Jurassic interval (from the Mesozoic era) – well-known for the abundance of dinosaurs at this time. To view the geologic timescale
Step one towards understanding the place to look for fossils is to appreciate the distribution of fossil bearing rocks and the circumstances that led to their formation and subsequent exposure. The rocks reveal the circumstances present at the time of their formation and the forces that subsequently influenced their character.
There are three primary rock types: sedimentary, shaped from accumulated sediment, e.g. sand, silt and skeletal stays; igneous, formed from molten rock that has cooled and hardened; and metamorphic, sedimentary or igneous rocks which were altered significantly by heat and/or pressure.
Fossils are most commonly found within sedimentary rocks as a result of favourable situations of burial and restricted alteration via time. Sedimentary rocks kind on the Earth’s surface as sediment accumulates in rivers, lakes and on the seafloor in particular. Among the common sedimentary rocks embrace: sandstone, composed predominantly of grains of eroded rock; limestone, composed predominantly of shell debris and Ordovician
planktonic skeletons; and shale, formed from hardened clay (initially deposited as mud).
Sedimentary rocks might endure considerable change tens of millions of years after deposition leading to a new rock type, e.g. slate. These ‘altered’ rocks are collectively often known as metamorphic. Slate was initially laid down as a muddy sediment which was then compacted and hardened to kind shale (a sedimentary rock), over time the shale was exposed to larger pressure and heat within the ground, a result of continental movement and/or tectonic activity. Over time the fabric of the shale was altered, changing the original fabric and changing it to a metamorphic rock, consequently fossils within the slate are often flattened and distorted.
On very rare events fossils can also be discovered within igneous rocks where molten rock escapes to the Earth’s surface and envelops organisms in its path, corresponding to a tree. In this example if the molten rock cools and hardens in less time than it takes to show the tree to ash, then the hardened rock may form a strong mould across the tree. Over a brief period of time the tree tissues decay leaving an empty chamber inside the rock, some examples even preserve the texture of the outer bark on the partitions of the mould.
Having recognised unaltered sedimentary deposits as the primary source for fossils, the subsequent step is to understand where such rocks are located. Geology maps are a helpful place to begin as they reveal the age and type of rocks present on the surface; note that the surface rock is mostly underlain by older rocks unless significant geological forces have caused buckling/folding of the landscape.