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. This EarthCache takes you to the Quartz Conglomerate boulders in Rock City Park, Olean NY. These unique rocks are part of a process from millions and millions of years ago, and they have been shaped by a variety of processes into what you see today. This particular earthcache looks to examine a unique set of veins in the side of one of the rock faces within the park, including how they were exposed and what they are made of
Please Note: Rock City Park is a private attraction that is open from May to October annually from 9am until 5pm. The park may close early in case of inclement weather or private events within the park. There is a fee of $8.00 per adult/$5.00 per child to enter the park. This Earthcache has been placed with the permission of park manager Nate Smith. A big thanks to bigguy14760 for obtaining permission from Nate and assisting with the creation of this earthcache.
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 GZ, you should be standing at the bottom of Rock City Park, staring up at a large rock face. About half way up the rock face, you will notice some strange lines poking out of the rock - these are mineral veins and were caused by differential weathering. Just in case you're having trouble identifying what you're looking for, they are visible in the photo below, just above my head (taken May 15, 2025).
Questions to Answer:
1. At the posted coordinates, locate a vein exposed in a large rock face. Describe its color, width, and length, and approximately how far up the rock face it is. Does it appear raised or recessed compared to the surrounding rock?
2. Based on the appearance (you won't be able to feel them, as rock climbing is prohibited in the park), what mineral do you think the vein is made of (quartz, calcite, iron oxide, etc.)?
3. Touch the rock face (at a level you can reach). Does it feel smooth or rough? Describe any forms of weathering you think might have contibuted to the texture of the rock.
4. Based on what you’ve observed and learned, explain why veins may help geologists understand the rock’s history, and how they formed after the host rock.
5. Photo: Include a photograph of yourself, your GPS, a signature item, thumbs up, etc at your favourite formation within rock city park. You do not need to show your face in the photo, but your photo must be unique to you. In the event of group photos, please have each member of your group upload the photo (each log should have at least one photo uploaded).
Earth Science Lesson: Veins and the Story they Tell
What is Differential Weathering?
Differential weathering occurs when various parts of a rock mass weather at different rates due to differences in hardness, mineral composition, porosity, or chemical resistance. Over time, the more resistant materials stand out as ridges or features, while the less resistant materials wear away faster, leaving depressions or smooth surfaces.
At Rock City Park, the exposed rocks are part of the Olean Conglomerate, a Pennsylvanian-aged (roughly 300 million years old) rock unit composed primarily of quartz pebbles and sand-sized grains cemented in a siliceous or iron-rich matrix. As this massive rock slowly weathers, veins of more resistant or chemically different material become exposed. However, the entire rock isn't one solid mass of conglomerate - there are veins of other minerals running through the conglomerate. These veins have a different hardness and will weather differently than the surrounding conglomerate, which is (relatively) soft in comparison. Because these veins are able to withstand the elements and erosion better than the conglomerate, they wear away atg a different rate: hence, differential weathering.
How Do Veins Form in Rock?
Veins form when mineral-rich fluids move through fractures or faults in rock. These fluids deposit crystalline minerals into cracks as they cool and the pressure decreases. Over time, these veins solidify, often appearing as lighter or darker bands that cut across or intrude into the host rock. They are generally chemically distinct from the surrounding matrix.
At Rock City Park, veins seen in the conglomerate cliffs and boulders may be composed of:
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Quartz – a hard, crystalline mineral highly resistant to weathering
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Calcite – softer, reacts to dilute hydrochloric acid, weathers faster than quartz
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Iron oxides (hematite, limonite) – often reddish, brown, or yellow; sometimes form “rusty” streaks
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Silica cement – clearer or glassy white, often forming hard veins
These veins formed after the host rock solidified, when groundwater percolated through cracks and deposited these minerals.
Why Do Veins Weather Differently?
The composition of veins determines how they react to weathering:
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Quartz veins weather very slowly, often forming ridges.
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Calcite veins weather faster than quartz or sandstone, often leaving grooves.
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Iron oxide veins may stain surrounding rock and change color over time, but are moderately resistant.
In conglomerate, which contains softer sandstone material between the pebbles, harder veins resist erosion and may protrude, while softer veins may dissolve or wear down faster.
The fact that veins only exist in specific locations is due to:
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Fractures and joints in the rock where mineralizing fluids could flow
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Geological stress zones where pressure opened pathways for fluid movement
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Chemical conditions that favored deposition in certain fractures
How to Identify Veins in the Field:
When exploring the boulders and cliffs of Rock City Park, look for:
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Linear bands of material that cross or cut through the pebble-filled matrix
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Color differences – veins may appear white, yellow, red, or dark gray
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Texture differences – veins may be smoother, shinier, or more crystalline
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Resistance – veins may protrude (harder) or be recessed (softer)
Additional Notes:
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Please stay on the marked trails and avoid damaging lichen or rock surfaces.
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Do not chip or sample the veins—photography and visual observation only.
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Rock City Park is privately operated and charges a small admission fee during open seasons.
This cache was placed by a PROUD Platinum Earthcache Master.
