ASP- Correlation Between Flow Magnitude & Erosion EarthCache

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 the relationship between flow magnitude (how fast the water is flowing) and erosion, using Bridal Veil Falls as a spectacular backdrop for this lesson. 

The Bridal Veil Falls is a short hike, less than a mile round trip, and is located within Allegany State Park. Please note that this trail has many exposed roots and trip hazards, involves changes in elevation, and may require wading during the spring or after significant rain. The park does have an entrance fee from Memorial Day weekend until the end of October, and access may be seasonal.

This Earthcache is developed with permission of the Office of Parks - Recreation and Historic Preservation at Allegany State Park and has been given permit number AL-25-5 on April 24, 2025.

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 will locate Bridal Veil Falls a short palk from parking. Study the falls, and how much water is currently falling. Notice how there are exposed roots between the shale layers, and large pieces of shale in files at the bottom of the falls - these are the results of erosion. You can find more information about these in the description below, as you answer the required questions for this earthcache:

Questions to Answer 

1. Water Flow Measurement: Estimate the magnitude of the falling water during your visit. Use a vessel of known volume (such as a water bottle) and at stopwatch (most cell phones have this ability) - compare this to the Magnitude of Flow Chart to determine your result. Include your date and time of visit.

2. Erosion Observation: Take a look at the cliff, and describe two different ways water is eroding the cliff. In your own words, please explain whether you think these will continue to erode Bridal Veil Falls.

3. Correlation between Flow and Erosion: In your own words, describe why you think a higher rate of water flow would have more of an impact on erosion of the falls, and what could be done to prevent further erosion from happening to this location?

4. Erosion Rate Estimation: Assuming an average flow magnitude of 4.5 over the course of the year and an erosion rate of 2–3 millimeters per year, calculate how many years it would take for the waterfall to retreat 15 feet (5 metres).

5. Photo: Mandatory: Include a photograph of yourself, your GPS, a signature item, thumbs up, etc at the falls (please note: you cannot complete the requirements for this cache by only visiting the trailhead, so a photo at the trailhead will not be accepted). You do not need to show your face in the photo, but your photo must be unique to you. Each log must include their own photo. 

Please send me the answers using the Geocaching Message Center or send me an email with your answers to the above questions, then go ahead and log this earthcache. You do not need to wait for my response to log. I will contact you if there are any issues with your answers. Feel free to post additional pictures as well, but please do not post your answers with your log.

Geology Lesson

Welcome to Bridal Veil Falls. This EarthCache will take you on a scientific journey to explore erosion, rock formations, waterfall dynamics, and how waterfalls actively reshape the landscape using Bridal Veil Falls as the example.

Bridal Veil Falls is a tributary stream of Stoddard Creek, cascading over a shale cliff formed primarily of the Salamanca Conglomerate. The waterfall drops approximately 39 feet (12 meters) over a narrow 2-foot-wide crest, facing southeast. It is classified as a seasonal waterfall, showing high flow in spring and early summer but often dwindling to a trickle during drier months. The name "Bridal Veil" perfectly captures the delicate, lacy appearance the water often takes, especially when the flow is light and the water fans out over the rock face.

During high flow, Bridal Veil Falls most closely resembles a plunge waterfall, with its water leaping outward from the narrow crest before falling to the plunge pool below.

Waterfalls and Their Role in Shaping Landscapes

Waterfalls are dynamic sculptors of the earth's surface. Over time, they:

• Smooth and flatten rocks at the crest by abrasive water flow and friction between rocks and particles in the flow of water, which act like sandpaper

• Erode the cliff face through mechanical and chemical processes such as lichen or algae growth, freeze-thaw wedging, and dissolution of the matrices between the conglomerate, eventually removing the clasts and leaving caps for water to pool

• Deepen the plunge pool at the base via forceful water impact, also called Scour

Key Erosion Mechanisms at Waterfalls

Several types of erosion work together at waterfalls:

Hydraulic Action occurs as water forces air into cracks within the rock, gradually weakening and breaking it apart.
Freeze-Thaw Action occurs when water enters cracks within the rock and then freezes, expanding and forcing the cracks to become even wider.
Abrasion takes place when sediments and small rocks carried by the water grind against the rock surface.
Solution or chemical weathering happens when slightly acidic water dissolves minerals in the rock.
Attrition further breaks down rock fragments as they collide with one another, making them smaller and rounder over time.
Biological weathering occurs when plants, lichen or algae grow near the waterfall and cause 

These forces, though invisible moment to moment, drive profound geological change over the span of decades and centuries.

The Rock-Water Relationship

At Bridal Veil Falls, the waterfall flows over a bed of harder conglomerate rock, a sedimentary rock composed of pebbles and sand cemented together. Beneath this resistant layer lies shale, a much softer rock formed from compacted clay and silt.

Because shale is less resistant to erosion, the waterfall tends to undercut the cliff face. Over time, water wears away the shale underneath the harder conglomerate, creating a shelf-like overhang. Eventually, the unsupported rock above collapses, causing the waterfall to "retreat" upstream. This process is known as undercutting, a fundamental force in waterfall evolution.

Scour refers to the powerful erosive action of swirling water and sediment at the base of a waterfall. As water plunges downward with high velocity, it creates intense turbulence in the plunge pool. This turbulence, combined with abrasive materials like sand, gravel, and rocks, grinds into the bedrock, deepening and widening the pool over time. Scour not only shapes the plunge pool but also contributes to undercutting the waterfall’s cliff face, helping the entire waterfall migrate upstream through gradual collapse and retreat.

Magnitude of Water Flow

Knowing the flow magnitude can help you understand how actively the waterfall is currently eroding the landscape. 

The rate at which Bridal Veil Falls changes depends greatly on the volume and velocity of the water. Higher flow rates increase the intensity of hydraulic action and abrasion, while greater heights amplify the impact forces at the plunge pool. Seasonal variations, such as spring snowmelt or heavy rainfall, create periods of particularly vigorous erosion.

Although Bridal Veil Falls is modest compared to giants like Niagara Falls, however the same powerful processes are at work here - gradually carving the landscape, one millimeter at a time.

Quick Facts about Shale

Shale is a sedimentary rock formed from fine-grained particles like clay and silt. It often appears thin-bedded and fractures easily along bedding planes. Shale makes up about 80% of all sedimentary rocks found in the Earth's crust. It can vary in color, appearing gray, black, green, red, or buff, depending on its mineral content.

At Bridal Veil Falls, the shale layers beneath the harder conglomerate provide a textbook example of how rock composition controls the pace and style of waterfall erosion.

This cache was placed by a PROUD Platinum Earthcache Master.