Excavating ammonites and other marine fossils in England’s Jurassic Coast.
Introduction
The Jurassic Coast, a UNESCO World Heritage Site, is renowned for its rich geological history and diverse marine fossils, including the fascinating ammonites. This coastal stretch spans from East Devon to Dorset in southern England and offers rockhounds and mineral collectors an unparalleled opportunity to explore the remnants of prehistoric life. Understanding the characteristics, formations, and historical significance of these fossils enhances the experience of both amateur and seasoned collectors.
Mineral Characteristics and Classification
Ammonites are marine mollusks with a coiled shell, characterized by intricate suture patterns that are useful for identification. belong to the class Cephalopoda, which includes modern-day squid and octopi. Their classification involves several orders and families, with notable examples being the Ammonitida and Pachyceras.
Geological Formation and Occurrence
The Jurassic Coast showcases around 185 million years of geological history. The ammonites unearthed here are primarily found in sedimentary rock formations, specifically in the Lias and Chalk Groups, which were formed during the Mesozoic Era. e deposits often yield ammonites in varying sizes and shapes, which provide critical insights into the Earths historical climate and sea levels.
Historical Significance and Uses
Historically, ammonites have been utilized for ornamental purposes, crafted into jewelry and home décor items. Their symbolism often represents change and evolution, making them sought-after items in metaphysical circles. Also, ammonite fossils play an essential role in paleontological research, contributing to our understanding of ancient marine ecosystems.
Physical Properties
Crystal System and Structure
Ammonites are not minerals in the traditional sense but are fossilized remains of marine life. r shells are made of aragonite, a form of calcium carbonate. The crystal structure of aragonite is orthorhombic, which helps give ammonite fossils their distinctive features.
Color and Luster
Ammonites display a spectrum of colors, often presenting iridescent hues due to their mineral content and fossilization process. The luster appears calcitic or pearly, particularly on polished surfaces, which adds to their decorative appeal.
Hardness and Specific Gravity
On the Mohs scale of mineral hardness, aragonite measures between 3.5 and 4.5. Its specific gravity typically ranges from 2.6 to 2.9, which collectors should consider when evaluating specimens for weight and quality.
Cleavage and Fracture Patterns
Ammonites exhibit a distinct form of fracture called conchoidal fracture, characterized by smooth, curved surfaces. This is particularly apparent when the fossil is broken, as it highlights their shells once-coiled structure.
Associated Minerals
Often found alongside ammonites are other fossils such as belemnites, echinoids, and even plant fossils. Mineral associations may also include calcite, pyrite, and siderite, which can enhance the overall aesthetic and collectible value of a specimen.
Where to Find It
Geological Environments
Ammonite fossils can be located primarily in coastal cliffs and eroding sea beds. best environments for collecting are those with loose sedimentary rocks, where erosion has exposed fossil layers.
Notable Locations Worldwide
While the Jurassic Coast is prime for ammonite collecting, notable locations globally include the Kimmeridge Clay in England, the Solnhofen Limestone in Germany, and the Pierre Shale in the United States. Each of these sites offers unique species and exceptional preservation.
Best Collecting Sites
- Lyme Regis
- Charmouth
- Seatown
- Whitesands Bay
Seasonal Considerations
The best time for fossil collection along the Jurassic Coast is during spring and summer, particularly after storms, which can reveal new specimens. Tide schedules should also be consulted to ensure safety and accessibility.
Collecting Methods
Required Tools and Equipment
Essential tools for collecting ammonites include:
- Small hammer and chisels for extracting fossils
- Safety goggles and gloves
- A brush for cleaning exposed fossils
- A geological pick for rough terrains
- Collection bags for transporting specimens
Extraction Techniques
Fossil extraction involves careful removal of surrounding sediment. Using a hammer and chisel, collectors should work gradually around the fossil to avoid damage. In some cases, wetting the area can loosen sediment and reduce the risk of breakage.
Safety Considerations
Safety is paramount when fossil hunting. Collectors should be aware of the potential for rockfalls, particularly in coastal areas. Wearing sturdy footwear and a hard hat is advisable when working near cliffs.
Cleaning and Preservation
After collection, it is vital to clean the fossils gently using a brush and water, avoiding harsh chemicals that can damage them. Proper preservation techniques, such as applying a clear coat of conservation wax, can enhance appearance and longevity.
Value and Uses
Commercial Value
Ammonites can fetch a considerable price in fossil markets, with values ranging from a few pounds for common specimens to thousands for rare or exceptionally preserved fossils. The price is often determined by size, rarity, and overall aesthetic.
Collectors Value
For collectors, ammonites are prized for their unique patterns and historical significance. can also serve as conversation pieces in home collections.
Industrial Applications
In some cases, ammonite fossils are processed for flour in various industries, and their calcium carbonate content can be utilized in the manufacture of cement and glass.
Lapidary Uses
Polished ammonites are often used in jewelry and decorative items, with their intricate shapes creating stunning visual displays.
Metaphysical Properties (if applicable)
Many enthusiasts believe that ammonite fossils carry metaphysical properties, promoting positive change and spiritual growth. They are often used in healing practices and are thought to facilitate communication and prosperity.
Legal Considerations
Collecting Regulations
Collectors must adhere to local regulations when foraging for fossils. In the UK, specific areas are protected and require permits for collection.
Land Ownership Issues
Understanding land ownership is crucial. Many sites along the Jurassic Coast are on private land, and permission is required before collecting.
Protected Species Status
Certain fossils may be part of a protected species or require special considerations. It is essential to research regulations prior to collecting.
Export/Import Considerations
Collectors looking to export ammonites should familiarize themselves with international laws regarding fossil exportation, ensuring compliance to avoid legal issues.
Conclusion
Excavating ammonites and other marine fossils along Englands Jurassic Coast presents an exciting opportunity for rockhounds and collectors to connect with the Earths ancient history. By understanding the geological and historical context, employing proper collecting methods, and adhering to legal considerations, enthusiasts can enjoy a rewarding and sustainable fossil-collecting experience. As you embark on your journey, remember to prioritize safety and ethics while expanding your mineral collection.
