What is the Rhynie Chert?
The Rhynie chert is a fossil bed located near the village of Rhynie in Scotland. It is famous for containing exceptionally preserved fossils of some of the earliest known terrestrial life, including both plants and animals (arthropods). The Rhynie chert is dated to the Early Devonian, about 396 million years ago. The preservation is so remarkable that the outlines of individual cells can be observed when the chert is polished. Chert is a sedimentary rock composed of an agglomeration of several different quartz varieties. At Rhynie, the fossiliferous strata formed when a hot spring released silicaeous water which rose and preserved the plants and animals in situ. The ecosystem was mineralized in excellent condition, for us to discover 396 million years later. A modern-day example of this phenomenon would be at the hot springs at Yellowstone Park in the United States. The land plant fossils preserved in the Rhynie chert are the best and most diverse of their age, making the chert a corne
Chert is a sedimentary rock comprised primarily of very finely crystalline silica minerals, mainly a number of varieties of quartz. Some cherts are formed from the accumulation of siliceous animal remains such as radiolaria, diatoms or sponge spicules. Most, however, are formed by chemical precipitation from silica rich fluids either within or replacing pre-existing sediments after they have been buried, or more rarely as a primary surface deposit. The ‘Rhynie chert’ falls into this last category and was originally deposited as sinter from ancient hot springs. It is a rather unusual variety of bedded chert of predominantly dark blue-grey colours that is of Early Devonian (Pragian) age, between 400 and 412 million years old (see inset right). The most remarkable feature of this particular rock is that it contains exceptionally well preserved fossils of some of the earliest plants and animals to colonise the land. Right: A polished slab of the Rhynie chert. This shows a vertical section
