To visit Halls Falls, the walk will take you on an undulating but well formed track with few steep sections, the walk took us just under and hour stopping for many photo's along the way.
What is a Waterfall? A waterfall is a river or other body of water's steep fall over a rocky ledge. This is actually a process of erosion, the wearing away of earth, it plays an important part in the formation of waterfalls, waterfalls themselves also contribute to the erosion process.
Waterfalls generally form as a stream flows from soft rock to hard rock. This happens both laterally (as a stream flows across the earth) and vertically (as the stream drops in a waterfall). In both cases, the soft rock erodes, leaving a hard ledge over which the stream falls.
A fall line is the imaginary line along which parallel rivers plunge as they flow from uplands to lowlands. Many waterfalls in an area help geologists and hydrologists determine a region's fall line and underlying rock structure.
As a stream flows, it carries sediment. The sediment can be microscopic silt, pebbles, or even boulders. Sediment can erode stream beds made of soft rock, such as sandstone or limestone. Eventually, the stream's channel cuts so deep into the stream bed that only a harder rock, such as granite, remains. Waterfalls develop as these granite formations form cliffs and ledges.
A stream's velocity increases as it nears a waterfall, increasing the amount of erosion taking place. The movement of water at the top of a waterfall can erode rocks to be very flat and smooth. Rushing water and sediment topple over the waterfall, eroding the plunge pool at the base. The crashing flow of the water may also create powerful whirlpools that erode the rock of the plunge pool beneath them.
The resulting erosion at the base of a waterfall can be very dramatic and cause the waterfall to "recede." The area behind the waterfall is worn away, creating a hollow, cave-like structure called a "rock shelter." Eventually, the rocky ledge (called the outcropping) may tumble down, sending boulders into the stream bed and plunge pool below. This causes the waterfall to "recede" many meters upstream. The waterfall erosion process starts again, breaking down the boulders of the former outcropping.
Erosion is just one process that can form waterfalls. A waterfall may form across a fault, or crack in the Earth’s surface. An earthquake, landslide, glacier, or volcano may also disrupt stream beds and help create waterfalls.
To log this Earth Cache, we require you to visit the listed waypoints to make some observations, consider the information given, then message us with the following answers to the best of your ability.
1. At the posted coordinates, describe the geological features you can see that make you believe you are looking at a waterfall (don’t over think your answer)
2. Depending on the flow of the stream you might not be able to get right to this WP, get as close as you can safely. There is a distinct feature here, is it a result of the waterfalls natural erosional process?
3. Thinking about your answer to the last question, describe how the feature you have identified is contributing to the stream? Do you think it will last for a short or long time? Why?
4. A photo of your team or GPS at, in or around the falls (please be careful) , upload as many photos as you like!
You are welcome to log your answers straight away to keep your TB's and Stats in order but please message us with your answers within a couple of days. Cachers who do not fulfil this Earth Cache requirement will have their logs deleted without notice.
Source: National Geographic, Wikipedia