Reedy Falls EC Sediment Transport&Stream Evolution 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 and studying unique geological features of the area, and  you will need to answers questions and/or post a photo to youir found-it log in order to claim a find.

QUESTIONS/TASKS TO DO IN ORDER TO COMPLETE YOUR FIND OF THIS EARTHCACHE. SEND ME THE ANSWERS (in an email or message through geocaching.com) TO AT LEAST ONE OF THE FOLLOWING (OR POST TO YOU LOG IF DOING THE PHOTO OPTION) Preferably THE SAME DAY YOU LOG YOUR FIND:

1) Sediment Transport and Deposition: Describe the types of sediments you see downstream of the falls (e.g., sand, gravel, silt) ______.
2) Erosion at the Falls: Observe the rocks at the base of the falls. Are they smooth (rounded) or jagged (angular)? __________.
3) Stream Evolution: Look downstream from the falls. Can you find any evidence of previous waterfall locations, such as cliffs or changes in the river’s elevation? _________.
4): Photographic Evidence: POST TO YOUR LOG a photo of the area around you (with you or your GPS device in it if you prefer). It would be great to have the falls in your photo.

***************************NOW FOR THE EARTHCACHE***************

The Reedy River is a dynamic waterway that over thousands of years has shaped the landscape of downtown Greenville, SC. This EarthCache can be done from the posted coordinates or, alternatively, the cacher can go down below for a closer experience.

Earth Science Lesson: This EarthCache focuses on the processes of sediment transport, deposition, and erosion, highlighting their roles in shaping the river’s course and the surrounding landscape. Geocachers will explore how the falls influence these processes and learn about the potential upstream migration of waterfalls over geological time. Cachers will gain a better understanding of these processes by observing their real-world manifestations at the Reedy River.

Educational Objective: This EarthCache will teach cachers about sediment transport mechanisms, how sediment deposition affects the river’s morphology, and how the erosional forces at the falls contribute to their potential upstream movement. Visitors will gain insights into stream evolution and observe evidence of these processes at the site.

Background Information:

1. Sediment Transport and Deposition:

   • Rivers carry sediment in three main ways: dissolved load, suspended load, and bedload.

   • As the river flows over the falls and into slower-moving sections downstream, it loses energy, depositing heavier sediments like sand and gravel.

   • Over time, sediment deposition can create features such as point bars, sandbanks, and changes in channel shape.

2. Erosion and Stream Evolution:

   • Waterfalls often form when a harder, more resistant rock layer overlays softer rock. Erosion at the base (through hydraulic action and abrasion) undercuts the softer rock, creating a plunge pool. Plunge pools form due to the force of water falling vertically and swirling at the base of the falls. This turbulence erodes the softer rock, enlarging the pool over time.

   • Rocks in the plunge pool can be angular if freshly broken from the cliff above or smooth if they have been tumbled and abraded by water and sediment over time. Jagged rocks indicate recent erosion, while rounded ones suggest prolonged movement and collision in the pool.

   • Over time, this process can cause the waterfall to migrate upstream as the overlying harder rock collapses.

   • Evidence of past waterfall locations can sometimes be observed in riverbed features or cliffs downstream.

Field Observations and Evidence:

• Sediment Deposition: Look for evidence of sediment deposition along the riverbanks downstream. These might include:

  • Sandbars or gravel deposits.

  • Fine silt or clay layers on the riverbanks.

• Erosion: Look at the plunge pool at the base of the falls and any undercut rock formations. Note the angular boulders and smaller sediments downstream, which likely eroded from the falls. (See above under Erosion and Stream Evolution)

• Over time, this process can cause the waterfall to migrate upstream as the overlying harder rock collapses. This upstream migration occurs as the softer rock at the base erodes faster than the harder rock above, causing the cliff edge to retreat.

• Stream Evolution: Examine the cliffs or ledges downstream for signs of previous waterfall locations, such as eroded rock layers or changes in elevation along the riverbed. Evidence of past waterfall locations can sometimes be observed in riverbed features or cliffs downstream.

I hope you have enjoyed your time observing Table Rock, and have learned something of the local geology.

I have proudly earned the Geological Society of America's highest level: