Achanarras fossils and fossil collecting

Geological Tools

Some of the limestones are quite easy to split, but often the fish are in heavier 'thicker' beds which may be harder to split. It is best to take the right splitting tools, and ensure they are sharpened well.

Patience is require at this quarry, it is not as productive as it used to be due to years of over-collecting. Having said that, even recently major discoveries have been made! The difficult part is there are only two thin zones in many meters of the Achanarras beds that contain fish, the difficulty is trying to find the correct colour, there are many different coloured slate slabs here. Productivity is mainly based on the accuracy of identiflying the correct type of slabs to split.

You need to look at the side of the slabs for very fine laminated yellow and blue alternating bands, these are very close together and no more than 2mm thick between layers. Some bluish slabs contain a thick quartz layer between the sides of the slabs rather than layers, these contain fish fragments but no whole fish. The slabs are easy to split, it is best to experiment splitting a wide range and then using any finds as a template guide for the correct colour. Often if you split a slab to find a fish, other fish will also be in the same slab, plus the fish splits on two sides, you you also get at least two specimens for one split. There are several different species of which some are shown on a board at the site.

There have been several important finds at this site, including the arthropod Achanarraspis, the primitive jawless fish Cornovichthys, and, perhaps most significantly, a single specimen of the new fish, known as Actinolepis. This genus is a first record for Scotland and suggests there were links with Estonia in the Baltic region at the time, since that is the location of previously known finds of this genus. Actinolepis, a representative of a group of fossil fish known as placoderms was an armoured prehistoric fish. Its head and upper body was covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species. Placoderms were also among the first jawed fishes to evolve.

The Caithness Flagstones of the Achanarras Quarry from the Devonian period are of the Achanarras Beds. It is difficult to determine the exact zones since the quarry during the end of its production period started to infill with spoil. The fish beds are laminae, originated as non-glacial varves. The upper fish bed is between two beds of thinly-interlaminated siltstone and shale with mound structures where as the lower fish beds are between thicker laminae of shale and coarse siltstone and shale with shrinkage cracks. The fish bed can be easily seen since the upper fish bed is between two zones of a black bed with mound structures and the lower fish bed sits under a third black band.

(Dipterus valenciennesi (Agassiz))....[more]

Other similar locations

Thurso is another very good location where complete fish and fish fragments can be found. At Spital Quarry, fish fragments and complete finds can also be made. Fish can also be found at Cromarty, Tarbat Ness, John o' Groats, Queensferry, North Berwick and Eathie Some of the best fish come from County Durham. where a number of quarries yield some of the best specimens in the UK. Fish Remains from the Devonian can also be found at Portishead in Avon. Of course fossil fish can be found at many locations during many periods, such as fish from the Jurassic of Dorset, Cretaceous of Norfolk, Eocene of Essex, Pleistocene Crags of Suffolk, and the Triassic beds from Aust and Blue Ancher along with many others.