Welcome to my Earthcache! An Earthcache is a special type of geocache where there is no container to find - instead you are looking for a unique geological feature of the area and need to answer questions, as well as posting a picture, in order to claim the find. The goal of this Earthcache is to educate visitors about fossils in the shale of the Marcellus formation (that's the shale that Bradford is built on top of). You will need to find some fossils at GZ, and send your answers to the cache owner along with your posted photo.
EARTHCACHE REQUIREMENTS
As with all of my ECs, I am not looking for PhD thesis level responses, but I am hoping that you take some time to enjoy the area and learn something new. Please include a list of all cachers with your answer, if answering for more than one caching name. There is no need to send individual answers.
To claim a 'find' for this Earthcache you must answer the following questions and send your answers in a message or email to the owner using the link at the top of the page. You can log your find with a photo at GZ. Send your answers to the tasks. I will be in contact if there is a problem, no need to wait for a response as long as the required photo is included in your log.
Observational Task
At the posted coordinates you will be standing in front of a shale outcropping, at the edge of a parking lot for a nearby store. Within that shale outcropping are... FOSSILS! Once you have observed the fossils and read the description of this cache page, you will be able to answer the required questions.
Questions to Answer
1. Have a close look at the shale located at GZ. Within the shale, locate three different fossils. Using the information in the description, try to identify the classification, type of fossil, and describe any other interesting characteristics about your fossil (such as it being complete, broken, larger than others who have seen, etc)
2. Try to identify what the fossils are using the information in the description and the infographic on the cache listing. Are all of the fossils you found the same type, or different types?
3. Have a close look at the shale surrounding the fossil. Can you Identify the matrix? Do the fossils appear to be secure in the matrix, or can they be easily removed?
4. Mandatory: Include a photograph of yourself, your GPS, a signature item, thumbs up, etc at the posted coordinates (Shale Outcropping). You do not need to show your face in the photo, but your photo must be unique to you. If you are caching with a group you can use the same photo, but each log must upload a photo.
Geology Lesson
Millions of years ago, this area was covered by a warm, shallow sea. That shallow sea was full of life, primarily ancient creatures that no longer exist today. Organisms that died were buried under tons of sediment such as sand and clay, many becoming fossilized under immence pressure and over the span of millions of years. Since most of McKean County was left unglaciated during the last major ice age, these fossils were not destroyed by the grinding action of the glaciers.
At the posted coordinates, you will find a small shale bank embedded predominantly with fossil molds, that formed more than 330 million years ago. These fossil molds give scientists information of what type of creatures lived millions of years ago, and how they shaped the flora and fauna we see today.
At the time that these creatures lived, this part of PA looked vastly different. Underwater creatures, such as the two most common fossils you will find here (arthropods - brachiopods and trilobites) were plentiful. But, how do we know what we're looking at?
FOSSILS
A fossil is any preserved remains, impression, or trace of a once-living organism from a past geological age, such as bones, shells, footprints, or even preserved amber with insects. The actual animal doesn't have to be present for it to be considered a fossil - fossils can also include footprints, petrified wood from ancient trees, petrified dung from creatures, and even burrows or dens that were made by animals that show how they lived and moved.
TYPES OF FOSSILS
There are FOUR main types of fossils:
TRUE FORM - This type of fossil is an actual bone, exoskeleton, or other part of the animal's body. Examples may include fossilized bones, shells, and teeth.
MOLD - This type of fossil is an impression where something organic used to be. For example, mold fossils may be present when an organism decays and breaks down, leaving the impression of its body where it decayed.
CAST - Just like making a piece of pottery or ceramic, a cast is when an impression fossil fills in with another type of material, different than the surrounding rock.
TRACE - This type of fossil is evidence left by the organism that does not contain any organic material, such as burrows, footprints, bite marks, and dens. It may also include other artefacts such as petrified dung that give an indication of how an animal lived or died.
HOW ARE FOSSILS FORMED?
There are SIX ways that organisms may turn into fossil.
UNALTERED - This happens when an animal is trapped (often alive) inside of a rock or sap unexpectedly, such as when a volcano errupts. One example of this that is quite common is insects found ion amber, which is a form of hardened tree sap.
PERMINERALIZATION and PETRIFICATION - This is the process by while minerals replace the tissues and cartiledge of the animal, creating a crystaline stone structure where the soft tissue used to be.
REPLACEMENT - This is a process where minerals replace the hard parts, such as bones and teeth, to form casts of what used to exist.
CARBONIZATION - During this process, any organic tissue, or anything that isn't carbon, is removed until only the carbon remains, which then gets hard.
RECRYSTALIZATION - This is the process by which small crystals turn into larger crystals, and typically takes millions of years to occur. One example of this process is the crystal growth within geodes.
AUTHIGENIC - This is a process that breaks down the fossils and leaves only traces of the previous organisms, as molds and casts are destroyed or dissolved through various processes.
WHY DO SOME STONES HOLD FOSSILS WHILE OTHERS DON'T?
This is actually a really complex question, with a lot of different factors to consider. However, for the sake of this earthcache, the simple answer is the MATRIX - The rock the fossils are embedded in is called the matrix. This can vary from soft to hard and be made of a number of different compounds. Fossils are most commonly found in SOFT matrixes, such as shale, limestone and sandstone, and are usually pretty rare in harder matrixes like granite and gabbros.
SOFT - You can use your fingers and a brush to extract the fossils.
HARD - Use of a tool is needed to extract the fossils.
WHAT TYPES OF ANIMALS MIGHT I FIND HERE?
During the Middle Devonian, common fossils include marine invertebrates like trilobites, brachiopods, corals, sponges, and cephalopods, along with early fish such as placoderms and sharks, and the beginnings of land plants like lycophytes, horsetails, and ferns.
Because this area was under a warm, shallow sea, a majority of what you will find here are marine invertibrates.
Marine Invertebrates:
- Trilobites: These extinct arthropods were abundant in the Devonian seas.
- Brachiopods: These "lamp shells" were common in both nearshore and offshore environments.
- Corals: Both tabulate and rugose corals thrived in the Devonian, forming reefs.
- Sponges: These simple, porous animals were also present in Devonian seas.
- Cephalopods: Goniatite ammonites, a type of cephalopod, were abundant in deeper waters.
- Echinoderms: Crinoids and other echinoderms were also common.
- Bryozoans (Moss Animals): These small, colonial animals formed encrusting or branching structures on hard surfaces.
- Bivalves: These shelled invertebrates, like clams, were found in sandy and silty environments.
- Gastropods: Snails and other gastropods were present in the Devonian seas.
- Stromatoporoids: Large colonial marine organisms similar to hydrozoans, which formed reefs.
- Ostracods: These small, shelled crustaceans were also present.
- Conodonts: Small, tooth-like fossils that are important for correlating Devonian strata.
This EarthCache has been prepared by a proud:
