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 how long the rocks have been in their current position using the study of lichenometry - the study of lichen and how their growth can be used to determine the age of rocks.
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, between several large bolders covered in various forms of lichen. You will need a ruler or tape measure to be able to answer the required questions.
Questions to Answer:
1. Lichen Identification: Within 10-15 feet of GZ, try to identify at least two different types of lichen growing on the rock formations. Describe their colour, texture, appearance, and any patterns of growth you notice.
2. Lichen Growth Measurement: Choose a sample of Map Lichen (read below to determine how to identify it) and measure the patch that you found. Include the approximate dimensions and whether it is sparse on the rock, or plentiful.
3. Lichenometry dating: Using the surface where you found the Map Lichen, Which lichenometry method would be most accurate for this surface? Based on your measurement and a known growth rate (e.g., 0.5 mm/year), how many years ago was this rock likely exposed?
4. 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: Lichens and the Story of Time
Rock City Park is home to spectacular boulders and bedrock outcrops that have remained exposed for hundreds to thousands of years. One of the most subtle but powerful indicators of this long history is lichen—a symbiotic organism formed from algae and fungi living together.
What Are Lichens?
Lichens are composite organisms formed by a symbiotic relationship between a fungus (which provides structure and protection) and a photosynthetic partner—either an alga or cyanobacterium (which produces food through photosynthesis). Because they don’t have roots, lichens draw moisture and nutrients from rain, air, and the rock or tree surface they're attached to.
Lichens are pioneer species, often among the first organisms to colonize bare rock surfaces. Because they grow slowly and remain attached to rock surfaces for centuries, lichens can be used to estimate how long a rock has been exposed to the elements. This technique is called lichenometry.
Lichens grow in a wide range of forms and colors and are often mistaken for moss. But unlike mosses, lichens are not plants—they don't have leaves, stems, or roots.
How Does Lichenometry Work?
Lichenometry uses the size of lichen thalli (body) to estimate the minimum time a rock surface has been exposed. It assumes that lichen began growing shortly after the rock became exposed and has grown at a steady rate. While the technique is most accurate for surfaces less than 1,000 years old, it can offer valuable insights for older exposures when used carefully.
Common Lichenometry Methods:
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LL (Largest Lichen): Measures the biggest visible lichen to estimate the maximum age.
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5LL (Five Largest Lichens): Averages the largest five for better reliability.
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FALL (Fixed Area Largest Lichen): Focuses on the biggest lichen in a defined space (~1 m⊃2;).
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SF (Size-Frequency): Uses lichen population data across size classes.
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LC (Lichen Cover): Estimates age by measuring how much surface area is covered.
Lichen and Rock Exposure at Rock City Park:
The massive boulders here are part of the Devonian-age Olean Conglomerate sandstone, weathered and exposed by glacial and post-glacial erosion. The lichens colonizing these surfaces tell a story of stability and time. By measuring their size and identifying their type, we can estimate how long a surface has remained undisturbed.
Lichen Species Common in New York:
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Rhizocarpon geographicum (Map Lichen):
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Yellow-green to fluorescent green patches with black outlines.
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Common in alpine and exposed rocky environments.
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Grows slowly—about 65 mm per 100 years in cold climates.
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Ideal for lichenometry due to its longevity and distinct form.
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Xanthoria elegans (Elegant Sunburst Lichen):
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Bright orange or red pigmentation.
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Often found where birds perch or in nutrient-enriched zones.
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More tolerant of pollution and moisture.
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Grows up to 0.5 mm/year after an initial colonization lag.
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Other Common Genera in New York:
Resources: