This EarthCache is designed to look at three waterfalls along the East Fork Jémez River and the Jémez River, in the Santa Fe National Forest, and compare the two very different ways they formed. We will be looking first at Jémez Falls (and another smaller waterfall upstream) formed in the common fashion and then at the Jémez Soda Dam Falls.
Jémez Falls and the smaller waterfall upstream have formed in the "classical" fashion as the water of the Jémez River drops over a step in the surrounding Cenozoic volcanic lava and tuff and loses elevation before continuing on. This is the most common way waterfalls form and I am sure you have all seen waterfalls formed in this way before so now we will look at the falls formed by the Soda Dam.
The Soda Dam is a natural dam formed by the mineral-laden waters of a neutral-chloride hot-spring discharge along the pre-caldera Jémez fault zone. These springs have strong chemical similarities to the deep fluids within the Valles Caldera. The conclusion generally drawn from this is that a hydrothermal outflow plume travels out of the caldera in the subsurface along the Jémez fault zone. The dam is composed of a buildup of travertine deposited on the rocks blocking the Jemez Canyon and is currently still enlarging. Travertine is a sedimentary rock which forms as calcium carbonate is deposited from water that is saturated with calcium bicarbonate. The dam developed where the hot-spring water cooled and precipitated calcium carbonate - not sodium bicarbonate as the name suggests.
The dam you are looking at was formed very slowly in layers as the water cooled leaving behind the travertine. This travertine is composed primarily of calcium carbonate, the mineral calcite. Calcite is deposited by groundwater saturated with the calcium and carbonate ions. This is mainly the result of the loss of carbon dioxide into the air. Saturation may also take place when the water evaporates.
Here's the chemical formula representing the dissolved mineral calcite precipitating out of the water:
Ca(HCO3)2 --> CaCO3 + H2O + CO2
This can also be represented as:
calcium bicarbonate --> calcite + water + carbon dioxide.
Travertine is often used as a building material. It is one of several popular natural stones that are used for countertops, flooring tiles, paving patios, and garden paths. The largest building in the world constructed mostly of travertine is the Colosseum in Rome. Other notable buildings using travertine extensively include the Sacré-Cœur Basilica in Paris and the Getty Center in Los Angeles, California.
The Jémez Soda Dam Falls occurs where the Soda Dam formed around the river and where the river now passes through as it continues its journey to the Rio Grande. This waterfall is formed as the river passes through the natural obstruction of the Soda Dam.
Coordinates and Directions:
Jémez Falls - Access to the parking area/trailhead is through the Jémez Falls Campground at the campground entrance coordinates. Parking is free, but if you would like to camp overnight, there are fees. From the parking area you will see the trailhead to the falls. Total round-trip distance is less than three quarters of a mile. The trail is dirt with a few rocks and it gets a bit rockier toward the end near the overlook. It is only a few hundred feet from Jémez Falls to the upper falls and that section is a bit rocky as well. As trails in the Jémez Mountains go, this is an easy one. The trail is well shaded and has very little elevation change. There are some steeps drops near the falls. In the interest of safety please be careful and do not go too near the edges. This trip should be fine for children if well supervised.
Parking/Trailhead - N 35 48.973 W 106 36.376
Campground Entrance - N 35 49.696 W 106 35.751
Jémez Falls - N 35 48.761 W 106 36.443
Upper Falls - N 35 48.776 W 106 36.380
Jémez Soda Dam - The Soda Dam, located at the posted coordinates, is only about 100 feet from the road and there is space for a few cars to park.
To claim this as a find:
1. Post a photo of yourself and your GPS with Jémez Falls in the background. (Optional but appreciated.)
2. Estimate the depth of the canyon below Jémez Falls?
3. Post a photo of yourself and your GPS with the Soda Dam in the background. (Optional but appreciated.)
4. Estimate the height of the Soda Dam?
5. See if you can find somewhere on the Soda Dam where the spring water (not the river) is coming out and estimate the flow rate. This can be gallons per minute, liters per minute, or whatever unit of measure you think is fitting. A good spot is the cave like opening (can be seen in the top left of the picture) under the overhang near the top of the dam just left of the waterfall - WATCH YOUR FOOTING - This area can be slippery.
E-mail the answers to me for numbers 2, 4, and 5 and post the photos for numbers 1 and 3 with your log within a few days.
Good luck and good caching.
- Rev Mike