Fossil Collecting on the Jurassic Coast

 

TESC 417 – Field Geology

Nels J. Parvi

1 SEP 2006

 

Abstract: This report is intended to summarize the knowledge that was gained in the field of paleontology through research conducted during a two week field geology course conducted on the Jurassic Coast of England. Encompassed in this report are the equipment necessary and some of the lessons learned to be more successful, what types of fossils may be found, and where fossils may be found. Examples of fossils that were found on the Jurassic Coast are included.

 

 

 “Fossils have been long studied as great curiosities, collected with great pains, treasured with great care and at a great expense, and shown and admired with as much pleasure as a child's hobby-horse is shown and admired by himself and his playfellows, because it is pretty; and this has been done by thousands who have never paid the least regard to that wonderful order and regularity with which nature has disposed of these singular productions, and assigned to each class its peculiar stratum.”

William Smith, January 5, 1796 (UCMP 2006)

Introduction:

Figure 1: The Jurassic Coast (WHC 2005)

 

   This report encompasses a two week field geology course to the Jurassic Coast in Southern England. This fully recognized World Heritage site extends from Old Harry Rocks near Studland on the east to the city of Exmouth on the west. The name ‘Jurassic Coast’ is actually a bit of a misnomer, however, because the entire Mesozoic Era, which includes the Triassic, Jurassic, and Cretaceous Periods, is represented along the coastline here. This geological anomaly is a result of the predominantly sedimentary rock in this area being uplifted and then tilted by tectonic activity. This has caused a slight dip in the exposed rock formations along this entire coastline, with the rocks being more recently formed when moving along the coast from west to east. This geological activity has resulted in a very unique and quite fascinating place to go with many natural wonders and panoramic views to see along the beaches and cliffs.

   The decision was made prior to departure that the personal focus of the course during this expedition would be on paleontology, which is defined as ‘the science of the forms of life existing in former geologic periods, as represented by their fossils’ (WNUAD 1996). As a person with absolutely zero prior experience in hunting for or collecting fossils, the realization soon set in that there was a lot to learn about the subject.

   Fossils are often formed from what was once a living organism, or occasionally from the aftereffects of their activities, such as footprints or worm burrows. Fossil formation is in itself a very complex process, because for a fossil to actually form and remain as a fossil it requires a lot of different things to go just right. For example, marine life usually flourishes along coastlines but for a fossil to actually become formed there it requires a minimum amount of water movement. This is because it is important that the water becomes stagnant in order to slow down the decomposition processes. An interesting side note to paleontology is that the majority of the life forms that have existed on Earth are not even represented in the fossil record (perhaps less than one percent), and this may even include what would have been considered a geologic period’s dominant species (Scriven2 2006).

   Another of the specific areas of interest for the course was the environmental conditions along the Jurassic Coast during these geological periods. The conditions during the Triassic Period, which lasted from about 251-202 million years ago, were more desert-like with terrestrial sediments from deserts and rivers being deposited (Scriven1 2006). Dinosaurs began to evolve during the Triassic Period, along with marine reptiles such as ichthyosaurs and plesiosaurs. However, the end of the Triassic Period was marked by the onset of the fragmentation of the supercontinent of Pangaea (Stanley 2005), and by a mass extinction of as much as 75 percent of some marine and terrestrial groups (SDNHM 2005).

   The Jurassic Period, which lasted from about 202-142 million years ago, saw warmer global conditions and the subsequent rise of global sea levels, and so marine mud rock, limestone, and sandstone were thus deposited (Scriven1 2006). Dinosaurs were the dominant creatures during the Jurassic Period, while mammals were small and insignificant. The first bird, Archaeopteryx, is also thought to have evolved during the Jurassic Period (SDNHM 2005). The end of the Jurassic Period was also marked by numerous extinctions, including many dinosaur species. As Pangaea continued to spread further apart it formed the Atlantic Ocean (Stanley 2005).  

   The Cretaceous Period lasted from about 142-65 million years ago, and during the first part of this period sea level alternately rose and fell. This resulted in different types of limestone being deposited during the periods when the surface was not exposed. The rise of the Alps then helped to tilt the underlying layers, thereby exposing them to erosion. When sea levels once again began to rise up it led to the deposition of sandstone, and then layers upon layers of chalk (Scriven1 2006). In fact, the overall trend during the Cretaceous period was for a rise in sea level, and much of the Earth’s continental land surface was covered by water. Dinosaurs reached their peak during the Cretaceous Period, and ammonites ruled the seas (so to speak); however, scientific evidence shows that an asteroid struck Earth at the end of the Cretaceous Period. This led to massive global species extinctions, to include the dinosaurs, ichthyosaurs, and plesiosaurs. The continents continued moving away from each other but were looking more and more as they look today (SDNHM 2005, Stanley 2005).  

   There are two main historical figures that rate mentioning when considering paleontology on the Jurassic Coast. The first is William Smith, who was born on March 23^rd, 1769 to a family of farmers. He became an assistant surveyor at the age of eighteen, which took him across the United Kingdom. He was the first person to recognize that fossils always appeared in the same sequence in sections of sedimentary rocks and that they could be used to determine the stratigraphy of sedimentary rocks throughout the United Kingdom. This is called the ‘principal of faunal succession’, and the basics of this system are still used today. Smith published his geological map in 1815, but he struggled financially for many years until he was finally recognized for his achievement with the inaugural Wollaston Medal from the Geological Society of London in 1831(UCMP1 2006).

Figure 2: Bust of William Smith at Oxford’s Natural History Museum (Parvi 2006)

 

Figure 3: Mary Anning

 (UCMP2 2006)

  

   The second person that requires mentioning is Mary Anning. She was born in Lyme Regis in 1799, and she began helping her father to collect fossils at an early age. She was helping to support her family by collecting fossils by the age of eleven, and she proved to be quite adept at finding them. In fact, during her lifetime Mary Anning made several scientifically important finds to include the first Ichthyosaurus skeleton in 1812, a nearly complete Plesiosaurus skeleton in 1823, and the first pterosaur skeleton found in England in 1828 (Goodhue 2001).

Materials & Methods:

   The fossil hunting code (CHCC 2006, JC1 2006) was written specifically for the Jurassic Coast, but many aspects of this code can be applied anywhere in the world fossils may be searched for. As such, it must be considered essential reading before setting out to hunt for fossils.

   The most important tool that a fossil hunter will need is undoubtedly the head, because therein lies the eyes and the mind. These are arguably the two most critical elements for fossil collecting. Keen observation skills, combined with a positive attitude, motivation, and a single-minded focus, are all essential elements that will surely lead to a rewarding experience. It is also important to dress appropriately when going out to look for fossils, so some prior knowledge of the area would be helpful in deciding what exactly the appropriate clothing and footwear may consist of. It is important to remember to always check the daily weather forecast, to use sunscreen, and, if applicable, to consult the local tide tables.  

   A geologist’s hammer (a hammer and chisel may be more precise), safety glasses, and a magnifying glass or hand lens are all vital tools that will come in handy regardless of the weather conditions. A hard hat is a necessity when working near cliffs because inevitably bits of rock will fall, especially in windy or wet conditions. As an alternative in less inclement weather conditions, a wide brimmed hat has proven to be an effective shield for your face and it will protect your head against the sun’s rays. A rain proof notebook and a writing utensil may also prove handy to have in order to record significant data such as where and when you found something. Trial and error has proved that paper towels are a good choice to wrap fossils in (newspaper would also do the trick). Some type of a hard case or perhaps a small box may also prove beneficial when transporting one’s finds, because some fossils are prone to crumble around the edges (or in some cases may even disintegrate completely). A camera is useful in recording the conditional state, the location where the fossil was found, and in establishing the stratigraphy of the surrounding rock. A small, lightweight backpack is convenient for carrying all of the tools, food, and water.

   At Charmouth, the local fossil collecting expert, Mr. Sam Scriven (Masters in Geology, University of Plymouth), gave the class a helpful tip for searching for fossils at this location. The trick is to look for worn, flat, gray rocks in which the sedimentary layers can be clearly seen on the thin edge. In some cases the fossils are already partially exposed even before the rock is broken open, but if there are no prior indications of a fossil then the rock should be broken open with the hammer by hitting on and around the thin side if the rock. Hopefully this will reveal a fossil (Scriven2 2006).    

Results:

 

   The first place that fossils were searched for was on the eastern edge of the Jurassic Coast on the Isle of Purbeck just north of Swanage at Old Harry Rocks. The fossil hunter might expect to find such fossils as belemnites, echinoids, corals, ammonites, and bivalves in the chalk formations here. Although no easily visible fossils were recovered by the class here, the majority of the material that makes up the layers of chalk seen at Old Harry Rocks is actually made up of microscopic fossils, called coccoliths, from the Cretaceous Period. Evidence shows that coccoliths once lived in abundance in the upper levels of deep warm seas (68° F or more), and when they died their skeletons sank to the bottom and combined with the remains of mollusks, foraminifera and ostracods (ANS 2006, GS 2002).

Figure 4: Old Harry Rocks (Parvi 2006)

 

 

   The next location that the class visited was Durlston Country Park, which is located just south of Swanage on the Isle of Purbeck. It is possible to find fossils of 24 separate species of fish in the Middle Purbeck strata at Durlston Country Park, although complete skeletons are rare. Some of the other fossils that may be found here are of reptiles, to include dwarf crocodiles and dinosaurs, shark teeth, mammals, echinoids, bivalves, and trace fossils (DCP 2002). Unfortunately, many of the fossils that were seen at Durlston Country Park can not be easily recovered as they are actually in the stone.

Figure 5: Kimmeridge Bay (Greengrove 2006)

  

   Kimmeridge Bay was the next place where the class searched for fossils, and this is where most of the class probably found their first ‘true’ fossils that could be collected and kept for personal use. Fossils that may be found here include

dinosaurs, ichthyosaurs, plesiosaurs, pterosaurs, crocodiles, turtles and tortoises, ammonites, and bivalves (SOES1 2003). Ammonites and bivalves proved relatively easy to find, but, unfortunately, the specimens that were found here were usually crushed because of the many years of intense compression between the layers of Kimmeridge Clay. One of the ammonites that was found at Kimmeridge Bay appears to be Aulacostephanus pseudomutabilis, based on the distinctive patterns exhibited around the body chamber (NHM 1983, SOES1 2003).

Figure 6: The Fossil Hunter’s first fossil, found at

Kimmeridge Bay, an ammonite believed to be

Aulacostephanus pseudomutabilis (Deraitus 2006)

 

   The bivalves that were found at Kimmeridge Bay appear to be Lucina minuscule, based on their small size, shell growth pattern, and shape (SOES1 2003).

Figure 7: More fossils found at Kimmeridge Bay,

bivalves believed to be Lucina minuscule. (Parvi 2006)

 

Figure 8: Lulworth Cove (Johnson 2006)

 

   Lulworth Cove proved interesting because there are so many of the different stratigraphic layers clearly represented here as you make your way around the edge of the cove. The Portland Beds at Lulworth Cove are known for containing fossils of ammonites (to include the giant ammonite Titanites), sponges, bivalves, and trace fossils (SOES3 2003). Portland Stone is largely made up of oolites that resemble tiny fossilized fish eggs, but they are actually grains of sand or organic matter that have been surrounded by limestone. It has been quarried and used extensively in architecture because of its composition which gives it a distinctive look. In the Purbeck formations, the fossil hunter may encounter fossils from fish, echinoids, gastropods, bivalves, arthropods, ostracods, vertebrates, charophytes and other various plants, and trace fossils (SOES2 2005). The Wealden Beds at Lulworth Cove may contain lignite (fossilized wood) and dinosaur fossils, although dinosaur fossils are more commonly found in the Wealden Beds on the Isle of Wight. The Upper and Lower Greensands may contain fossils of bivalves, echinoids, gastropods, ammonites, nautiloids, and trace fossils; however, the Gault that separates the Upper and Lower Greensands in Lulworth Cove does not usually contain fossils due to its poor constitution. The Chalk does not usually prove to be very good for fossils, either, but it may contain belemnites, ammonites, echinoids, corals, and bivalves (SOES3 2003).

   There were several fossils that were clearly visible as the class walked around the cove; however, because they were on the surface of the rocks, or contained within the rocks that were lying on the beach, it would have proven quite difficult to put a specific name to them. There were numerous examples of trace fossils on the surface of the rocks, of which at least some appeared to be chondrites (worm feeding burrows). Other fossil rocks appeared to be layers upon layers of fossilized shells of what appeared based on their rough shell surfaces to possibly be some type(s) of oysters. A bivalve fossil was found in the Greensand layer,

Figure 9: Bivalve fossil found in the Greensand strata at Lulworth Cove , believed to be Panopea gurgitis (Parvi 2006)

 

but it proved difficult to identify the fossil with a high degree of confidence; however, based on the size, shell growth pattern, and shape it is believed to be Panopea gurgitis (NHM 1983).

   The Fossil Forest is located on the side of the cliff just to the east of Lulworth Cove, and the remnants of an ancient forest can be seen here. The fossils that can be seen at the Fossil Forest are another example of trace fossils, called stromatolites, and they are all that remains of what had once been a richly forested peninsula that was subsequently covered over by rising seas. The

Figure 10: The Fossil Forest (Parvi 2006)

 

climate was much hotter back then, which led to evaporation and extremely salty water conditions. Nonetheless, a certain type of algae was able to flourish in these harsh conditions, and it grew on and around these submerged trees. The resultant algal deposits ended up becoming fossilized around the bases of the trees and formed doughnut shaped holes, or ‘burrs’, when the tree decomposed. There were also fallen trees that were covered by algae and fossilized; however, because they are not clearly evident to see now, it seems likely that this fossilized wood has been removed by people over the years (JC2  2006).

Figure 11: Sam Scriven explaining the geology of the
Jurassic Coast near Charmouth (Johnson 2006)

 

Figure 12: Belemnites found at Charmouth (Parvi 2006)

 

   The next site where the class looked for fossils was Charmouth, just to the east of Lyme Regis, and the beach area here proved to hold an abundance of diverse fossils. It is possible to find fossils of ichthyosaurs, plesiosaurs, ammonites, bivalves, crinoids, nautiloids, brachiopods, fish, dinosaurs, pterosaurs, various

plants, and trace fossils (SOES4 2006). The class was able to find numerous examples of ammonites (some pyritized), belemnites, echinoids, and crinoids. Unfortunately, some of the fossils at Charmouth were well contained inside of the rocks, or were found in broken bits that were mixed in with the beach rock. The fossil’s random locations on the beach made the positive identification of the species of the fossils difficult.

Figure 13: The cliff at Lyme Regis (Greengrove 2006)

 

The fossil hunter can expect to find the same types of fossils while searching at Lyme Regis as when at Charmouth, and there were high hopes (dreams, perhaps?) of making an important scientific discovery, or at least of finding some small part of an ichthyosaur or plesiosaur, at Lyme Regis, the home of Mary Anning. It is important to keep in mind, however, that Lyme Regis is a very popular area for fossil collecting, to include professional fossil hunters, because of the history of the area and the ever present potential of finding a new species or a rare fossil. That fact, combined with the fact that there are so many different types of fossils that can be found here, means that the area is combed over regularly and extensively. This may make it harder to find that rare or exquisite fossil the fossil hunter treasures, and, unfortunately, the only fossils that were found here were in the museum. The fossils contained therein were all quite interesting to see, though, and it came as a surprise to see first hand just how large an ichthyosaur could grow to be!

Figure 14: The cliff at West Bay (Johnson 2006)

 

   While at West Bay the class looked at the Bridport Sands, which may contain fossils of ammonites, belemnites, oysters, and trace fossils (UKGE1 2005). There were many trace fossils to be seen here, and what appeared to be bivalve fossils contained in the cliff, but there were no fossils physically recovered here.  

   The rest of the time spent during the course involved more cultural, historic, and aesthetic endeavors in Bath, Oxford, and London. There was no fossil hunting and the only fossils to be seen were in the museums and shops.    

Discussion: 

 

   Overall, this trip to the Jurassic Coast would have to be deemed a huge success simply because even with the lack of prior experience in doing this activity, the class was still able to locate a great many fossils. It is difficult to fully relate the exhilarating feeling that a person gets when they find their first fossil! There is a constant sense of discovery with each new fossil found, so the feeling never really gets old. Plus, the fossil hunting skills (and fossil maintenance skills) are constantly being enhanced as more experience is gained.

   There are a few tips that were learned that may help a prospective fossil hunter. Many of the fossils are contained in hard rock, so extra precautions must be taken when breaking the rock in order to extract a fossil so that the fossil is not ruined (or lost). If at all possible, the entire rock should be taken to a place where better tools and working conditions are available. A dentist’s drill, or perhaps a Dremel Tool, may allow for more precise removal of the fossil from the hard rock encasing it. Once the fossils have been recovered sufficiently, they can be made more presentable and their unique beauty enhanced with the use of rock cutters and polishers. Be aware that pyritized fossils are subject to further oxidation, so further steps should be taken to preserve the fossils by sealing them.

   It is important to remember to always be safe, and that the fossil hunter is responsible for their own actions at all times. Remember that in some cases the areas where fossils are searched for may be privately owned, so any extensive activity such as digging must be approved and coordinated in advance. In this type of situation more stringent safety measures may also have to be put in place. It is best to plan fossil hunting activities on a beach around the low tide, and to remember that the incoming tide is always a consideration that the fossil hunter must remain aware of. Many beaches are bordered closely by cliffs, and in a battle between a fossil hunter and the waves, the waves are likely to win. So don’t push your luck! It is important to be aware that major rock falls and mudflows could occur at any time, but especially during or after it rains. It is a good idea to not go out alone, and it is also important to always let someone know where you are going and when you plan to return. It would not hurt to have a working mobile phone, either.      

   Overall, this experience proved to be very exciting and rewarding, and it is recommended to anyone that enjoys being out in nature and exploring new things. Fossil hunting does not require a lot of specialized equipment or technical training, so basically anyone can do it and be successful at it.

   Thanks must be given to those in the class that were kind enough to turn in photographs from the Jurassic Coast for the class to use. This simple act adds a personal touch and undoubtedly will enhance the reports and presentations immensely.

   Mr. Scriven highly recommends a book of information about the geology of the Jurassic Coast entitled ‘The Ecology of Fossils’. It is edited by W.S. McKerrow, and apparently much of the presentation given by Mr. Scriven to the class at Charmouth was drawn from this book. Unfortunately, time constraints did not allow for the acquisition of this book prior to the completion of this report.

   The website provided by Dr. Ian West of The School of Ocean and Earth Sciences of the National Oceanography Centre, Southampton University, deserves special recognition and consideration. It is quite extensive and proved to be invaluable to this research. It is available at: http://www.soton.ac.uk/~imw/index.htm

 

 

References:

 

Chalk facts [Internet]. [GS] Geology Shop; c2001-2002 [cited 2006 Aug 25].  

 Available from: http://www.geologyshop.co.uk/chalk.htm

 

 

Chalk formation [Internet]. [ANS] Answers.com; c2006 [cited 2006 Aug 25].

 Available from: http://www.answers.com/topic/chalk-formation

 

[DCP] Durlston Country Park. 2002. Fossils of Durlston: Remnants of a past life.

 Durlston: Dorset County Council. 6 p.

 

 

Fossil forest [Internet]. [JC2] Jurassic Coast – The Jurassic Coast [cited 2006

 Aug 28]. Available from: http://www.jurassiccoast.com/index.jsp?articleid=2405

 

Fossil mysteries [Internet]. [SDNHM] San Diego Natural History Museum; c2005

 [cited 2006 Jul 7]. Available from:  http://www.sdnhm.org/fieldguide/fossils/timeline.html

Fossils of the Lias, at Lyme Regis etc. – Geology of the Dorset Coast [Internet].

 [SOES4] School of Ocean and Earth Sciences, Southhampton University; c2006

 [cited 2006 Aug 30]. Available from: http://www.soton.ac.uk/~imw/liasfos.htm

 

Goodhue TW. The faith of a fossilist: Mary Anning. 2001. Anglican and Episcopal

 History 70(1):80-100

 

Holidays on Dorset & East Devon’s World Heritage Coast [Internet]. [WHC]

 World Heritage Coast; c2005 [cited 2006 Aug 29]. Available from:

http://www.worldheritagecoast.net/

 

Kimmeridge Clay fossils – Geology of the Dorset Coast [Internet]. [SOES1]

 School of Ocean and Earth Sciences, Southhampton University; c2003 [cited  

 2006 Aug 24]. Available from: http://www.soton.ac.uk/~imw/kimfoss.htm

 

Mary Anning (1799-1847) [Internet]. [UCMP2] University of California, Berkeley

 Museum of Paleontology c1994-2006 [cited 2006 Aug 24]. Available from: http://www.ucmp.berkeley.edu/history/anning.html

 

[NHM] The Natural History Museum. 1983. British Mesozoic fossils. 6^th ed.

 United Kingdom: Intercept Limited. 209 p.

 

Durlston Bay, Swanage – 1. – Introduction & Upper Purbeck – Geology of the

 Dorset Coast [Internet]. [SOES2] School of Ocean and Earth Sciences, 

 Southhampton University; c2005 [cited 2006 Aug 29]. Available from: http://www.soton.ac.uk/~imw/durlston.htm#fossil

 

Scriven S. [Scriven1]. 2006. Introduction to the paleontology of Charmouth –  

 notes. 8 p.

 

Scriven S. [Scriven2]. 2006 Aug 1. Personal communication

 

Scriven S. [Scriven3]. 2006 Aug 26. Personal communication

 

Stanley, SM. 2005. Earth system history. 2^nd ed. New York (NY): WH Freeman

 and Company. P.567

 

Strata and fossils of the Lulworth Cove area - Geology of the Dorset Coast

 [Internet]. [SOES3] School of Ocean and Earth Sciences, Southhampton

 University; c2003 [cited 2006 Aug 29]. Available from: http://www.soton.ac.uk/~imw/lulstrat.htm

 

The fossil collecting code of conduct [Internet]. [JC1] Jurassic Coast – The

 Jurassic Coast [cited 2006 Jul 7]. Available from: http://www.jurassiccoast.com/index.jsp?articleid=26821

 

The West Dorset fossil collecting code of conduct [Internet]. [CHCC] Charmouth

 Heritage Coast Centre; [cited 2006 Jul 24]. Available from: http://www.charmouth.org/Pages/fossil%20code/West%20Dorset%20fossil%20code.PDF

 

UK Fossils Network - West Bay collecting guide [Internet]. [UKGE1]. United

 Kingdom Geologists Equipment Limited; c2005 [cited 2006 Aug 30]. Available

 from: http://www.ukfossils.co.uk/Fossils-and-Geology/West-Bay/Collecting-Fossils-from-West-Bay.htm

 

UK Fossils Network - West Bay location photos [Internet]. [UKGE2]. United

 Kingdom Geologists Equipment Limited; c2005 [cited 2006 Aug 31]. Available

 from: http://www.ukfossils.co.uk/Fossils-and-Geology/West-Bay/Location-Photos-for-West-Bay.htm

 

[WNUAD] Webster’s New Universal Unabridged Dictionary. 1996. USA: Barnes

 & Noble Books. 2230 p.

 

William Smith (1769-1839) [Internet]. [UCMP1] University of California, Berkeley

 Museum of Paleontology c1994-2006 [cited 2006 Aug 24]. Available from: http://www.ucmp.berkeley.edu/history/smith.html

 

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