As a geologist, I thought it only fitting that the first cache I created be an EarthCache. Have Fun!!
Whatcom Falls Park
Whatcom Falls Park is 241 acres of pure Pacific Northwest beauty located in Bellingham, Washington. Whatcom Creek runs through this heavily forested area that contains indigenous plants and trees. The creek is a natural outlet for Lake Whatcom, and runs a mere 4 miles from its headwaters down to the ocean at Bellingham Bay. More than 5 miles of hiking trails wind through the park; these are composed mainly of gravel and dirt with the occasional steep grade or set of stairs. Many other amenities, including 2 playgrounds, a fish hatchery, tennis courts, and an off leash dog area make this a popular destination for locals. Within the park boundaries, several waterfalls cascade along Whatcom Creek, the largest of which can be observed from a beautiful bridge of Chuckanut Sandstone built in 1939 near the main parking area. This sandstone is also the bedrock through which the creek cuts, and is but one of the reasons why such gorgeous waterfalls exist in this area. For more information on the park and its amenities, visit the City of Bellingham website.
Waterfall Formation
A waterfall is a feature in a river or stream where the flowing water cascades, or descends abruptly and vertically. These occur at nickpoints in the topography, places where the elevation of the stream changes sharply. Nickpoints can be formed in one of two ways: by a stream flowing over an area of very hard, resistant rock, or by tectonic uplift (which can occur along an active fault line) creating a “step,” or abrupt elevation change in the topography. The bedrock over which a river or stream runs is an important factor in the generation of waterfalls along that body of water. Different layers within bedrock have varying degrees of strength and resistance to erosion by the flowing water: some layers are hard and resistant, while others are soft and easily eroded.
An important component to forming a waterfall is to have a stream flowing in an area where hard, erosion resistant rock layers are underlain by softer, more easily eroded rock layers. The flowing stream cascades over the hard, erosion resistant layer. The water generates more energy in this vertical drop, which leads to undercutting and removal of the soft layer beneath the hard caprock (from the constant backsplash of water), and development of deep plunge pools directly under the waterfall. Over time, the undercutting causes the softer layer beneath the cap rock to retreat, leaving an overhang in the hardest layer. Clearly the overhang is doomed by gravity to collapse! This process continues and repeats, eventually leading to a backward retreat of the waterfall, and ultimately the waterfall completely erodes itself away. An excellent video animation of this process can be found on You Tube.
Why do waterfalls exist at Whatcom Falls Park?
Whatcom Creek flows through an area that is ideal for waterfall formation. The bedrock in this part of Washington consists of the Chuckanut Formation, which was deposited about 60 million years ago. The rock types within this formation include sandstone, shale, siltstone, conglomerate and coal. Sandstone tends to be much more resistant to erosion than either shale or siltstone. The alternating hard and soft layers in this formation are primarily responsible for the gorgeous waterfalls we see here today. But time is a huge factor too…this entire process can take thousands of years. Luckily, that means we can enjoy the falls for many, many years to come!
To claim this EarthCache:
1. Go to the bridge at the posted coordinates. This is the main and largest of the falls. Estimate the height of these falls. The way I estimate height is to have a person of known height stand nearby, and then imagine how many duplicates of that person stacked atop one another it would take to reach the given height! LOL
2. Cross the bridge and turn right (north-northeast). Continue along the gravel path to the next set of falls about 100 m upstream, near N 48° 45.157, W 122° 25.724. Estimate the height of these falls.
3. These two waterfalls are very different in size. Now that you know a bit about waterfall formation, make an educated guess as to why the difference in height exists between these two falls. There are several possibilities, just make a stab at it.
4. Optional: Take a selfie, or a group photo, or picture of the scenery at your favorite waterfall! I no longer live in the area and miss it very much, so I love seeing the falls at different times of the year. There will be plenty of people in the park to assist you if needed!
5. Email the answers to the above questions (please do not log the answers) to gratefulgirl16. Post your photo with your log on this page.
Explore the park if you are new to it! There are many amazing things to see. Further downstream, an area called “the Whirlpool” is a great example of a plunge pool. If you are lucky and it is a nice day, you’ll see swimmers jumping from a high cliff into the pool below. Or if you are daring, bring your suit!
References:
1. Friday, Chris, 1999, Whatcom Creek: A History of a Place: http://www.acadweb.wwu.edu/cpnws/rwc/Draftnar.htm, May 27, 2009.
2. City of Bellingham Parks and Recreation Website: http://www.cob.org/services/recreation/parks-trails/whatcom-falls-park.aspx, May 27, 2009.
3. Wycombe High School Virtual Learning Website: http://whs.moodledo.co.uk/file.php/1365/Fluvial%20systems/Waterfall2.swf, May 27, 2009.
4. Christopherson, R.W., 2001, Elemental Geosystems: Prentice-Hall, New Jersey, 586 p.