Jacobs Falls--Water from the Wilderness EarthCache

Jacobs Falls—Water From the Wilderness

Jacobs Falls is in the Keweenaw Peninsula of Upper Michigan along Highway 26. It is an example of a fan type of falls, spreading out as it descends, while maintaining contact with the rock. It does not have the same volume of flow that others may have, but it does have a special, rugged beauty of its own.

Jacob Falls is located along Highway 26. This waterfall occurs most spectacularly after a good rain fall, but will run during all but the driest times of the year.

A waterfall is where a body of water, such as a stream or river flows over erosion resistant rock with a sudden break in elevation. Often there are softer, more easily eroded rock layers underneath the harder layers of rock that break away due to gravity or are in fact eroded by “splashback”, water that comes over the falls and splashes back onto these softer rock. This may form a rock-shelter behind the falls, however we do not see this happening here. At the bottom of the falls the water has formed a ‘splash-pool’. This is where water coming over the edge has cleared away the smaller rocks and formed a circular cavity where water collects before moving downstream.

There are several different types of waterfalls, each with its own characteristics and some that combine multiple features rolled up into one. Below are some of the different types of falls.

• Block: Water descends vertically to form a wide stream or river.

• Cascade: Water descends a series of rock steps.

• Cataract: A large powerful waterfall, such as Cumberland or Niagara Falls.

• Fan: This is where the water spreads out horizontally as it descends while maintaining contact with the bedrock.

• Horsetail: Descending water maintains some contact with the bedrock.

• Plunge: Water descends vertically, losing contact with the surface of the bedrock.

• Punchbowl: Water descends in a constricted form and then spreads out into a wider pool.

• Segmented: Distinctly separate flows of water form as it descends.

• Tiered: Water drops in a series of distinct steps or falls.

• Multi-step: A series of waterfalls, one after another of roughly the same size, each with its own sunken plunge pool.

The Geology

The rock at this location is sedimentary sandstone and is not easily eroded compared to some other types of rock. Sand is often deposited in thick layers from one to several feet thick. Imagine a sandy beach that has had the grains cemented together forming a solid substance. The topsoil has been removed, exposing the rock underneath. Here we can see that the sandstone slopes at a downward angle giving rise to this type of water fall. At other locations that do have softer layers of rock underneath, such as the one pictured below, the free falling water has created a rock house behind the falls. Such areas were often used by Native American for shelter. However at this location this is not the case as there is little or no verticle drop.

Qualifications for Credit:

To get credit for this EarthCache, email the answers to the following questions and then post a picture of you and your GPSr with Jacob Falls clearly in the background when you log your find. Posts with no pictures or without emailing the answers will be deleted. If no picture is possible, for instance you dropped your camera in the creek, or the batteries died, let us know first and we will work something out.

Questions:

1. What type of waterfall is this classified as?

2. What is a ‘splash-pool’?

3. What type of rock is present at this location?

4. What is your estimated width of the exposed rock at this location ?

Credits and Ammosuperman EarthCaches

This EarthCache was created by a team of two Platinum EarthCache Masters, Ammosuperman EarthCaches are a collaborative effort. We have used resources such as the Internet and magazine articles as well as personal experience in visiting the sites, as research tools in its construction. Our goal is to learn more about our planet and to pass along what we have learned to others having similar interests. We hope you enjoy the experience.