Lesmahagow

Many important collections of Silurian arthropods and vertebrates have been made near Lesmahagow since the mid to late 1800’s. The Geological Society of Glasgow set up a camp in the 1890’s, which was aptly named “Camp Siluria”, from which members of the society collected a number of rare and complete specimens of fossil fish and eurypterids. It is now very difficult to obtain permission to collect from these rocks as a result of inappropriate collecting. It is still possible to find fossils from these rocks, but all fossils are rare and some may be usefully donated to a museum for research.

The Lesmahagow Inlier is a block of Silurian sediments surrounded by sediments of Carboniferous age. The inlier consists of shales and sandstones with occasional pebble conglomerates of a lagoon or lake. The lower parts of the succession contain occasional marine fossils, including trilobites and brachiopods, but the higher parts of the succession lack any evidence of marine incursions becoming influenced more by river and deltaic conditions. The sequence seen here is part of a general regression that can be traced from western Ireland to Scandinavia. The earlier (Cambro-Ordovician) terrane accretion of the Midland Valley Terrane to the Laurentian continent by sinistral strike-slip controlled basin development, sedimentary facies and deformation from Llandovery through until the early Devonian times.

Birk Knowes

Birk Knowes SSSI (Site of Special Scientific Interest and has special protection under Scots law) is also known as the Jamoytius Horizon named after the rare soft-bodied fish found from this locality. Sadly, due to overzealous collecting, this site has been made off-limits to all collecting for the time being. From the debris, we might be able to find a number of the rare fossil animals found at this locality such as Loganellia scotica (thelodont fish), Jamoytius kerwoodi (agnathan fish), Ainiktozoon loganense (?concavicarid arthropod), Ceratiocaris papilio (pod-shrimp), Pterygotus bilobus and Slimonia acuminata (eurypterids) as well as a number of other rare animals (see the images below). The silts and shales represented here are all from the Patrick Burn Formation and probably represent a shallow brackish-water lagoon with occasional marine incursions and high sediment input. The sediments are thought to be of Llandovery (Silurian) age. The sediments continue up sequence into blue slatey shales that contain eurypterids and pod-shrimps, but rarely any fish remains. These rocks can be found in the Kip Burn, Logan Water, Blaeberry Burn and at Dunside.

Birkenhead Burn

The Birkenhead Burn locality is also a SSSI. It has been collected from for over 100 years and has yielded many interesting complete fish and scorpions. Thelodonts like Lanarkia and other anaspids like Birkenia, Lasanius and Ateleaspis have also been found here. Rare examples of the eurypterid Lanarkopterus have also been found here. The rocks here are younger than Birk Knowes and are thought to be lower Wenlock (Silurian) in age. A typical fish bed consists of finely laminated yellow/green and brown fine to medium grain sediment. The fish are not found throuighout the sequence and are very rare (see images of some of the fish found here below).

Jamoytius from Birk Knowes, Lesmahagow	Lanarkia from the Birkenhead Burn, Lesmahagow	Loganellia from Birk Knowes, Lesmahagow
Birkenia from the Birkenhead Burn, Lesmahagow	Ainiktozoon from Birk Knowes, Lesmahagow	Lasanius from the Burkenhead Burn, Lesmahagow
Hughmilleria from the Kip Burn, Lesmahagow	Slimonia metastoma from the Kip Burn, Lesmahagow	Pterygotus from the Kip Burn, Lesmahagow

Pterygotus claw	Scorpion-like eurypterid
Ceratiocaris from Dunside	Ceratiocaris from Dunside

A strange structure found in the Shiel Burn, Lesmahagow

Many new discoveries have been made since the localities were first discovered in the early 19th century. Even very recently new types of fish and new strange fossils have been found by collectors. The above structure may be an early stage of a eurypterid, but may also be a spore capsule of an early plant. It is difficult to be absolutely sure at this stage as it has not been fully researched.

For more information on the fossils from Lesmahagow, do an internet search and you will find more fantastic fossils. Also, feel free to look at the collections in the Hunterian Museum at the University of Glasgow using the catalogue search facility.

For more on the fossils of Lesmahagow.

Lawson, JD and Weedon, DS 1992. Geological Excursions around Glasgow and Girvan. Geol Soc Glasgow. 495pp.
Lesmahagow fossils in the Hunterian Museum

Fossils from Lesmahagow

Introduction

Description

Birk Knowes

Birkenhead Burn