Grand Falls

Stop 4

Directions - The turnoff to Grand Falls can be found 12.9 miles from the point where you entered the Leupp Road near Winona. The turn is to the north, soon after you enter the reservation. Take rough dirt road past the Grand Falls Bible Church. Eventually this road intersects Navajo 70 and a few other spurs. Keep going toward the valley that you see in the distance. You slowly drop into it. You'll know you're at Grand Falls when you hit a river (or river bed) in the valley floor. You may park on the south side in the sandy area by the river or you might want to back up about half a mile and look for the weathered ramadas on the bluff overlooking this area.

You CAN cross the river above the falls during times of low water. (Watch for spring runoff and summer thunderstorms.) If you're like the lawsuit-happy folks in Phoenix who try to cross flooded washes and then whine when they get wet, too bad. You're not going to sue anybody out here if your vehicle gets swept away. As a child, one of my friends died here in a fall, so be careful around the cliffs. Personal responsibility!

Background - If you trace the watershed of the Little Colorado River on an Arizona map, you may be surprised how BIG an area this seemingly insignificant river drains. Much of the watershed is minimally vegetated and/or overgrazed so that when there IS rain, the runoff is sudden, intense, and short lived. The river both deposits much and erodes well.

If you happen to visit when there IS runoff, Grand Falls, higher than Niagara Falls, is a violent chocolate milkshake. The trail is slippery, the rocks are slickened with a coating of clay, your clothing will be stained. If you come here during a dry time, however, don't be disappointed. This is truly better for exploration. To get to the bottom of the falls, go west to the small basalt pinnacle. Descend into the canyon there.

The three sedimentary formations to examine, from top to bottom, are the Moenkopi Formation, Kaibab Limestone and Coconino Sandstone.

The knolls on the north side of the crossing are Moenkopi Formation, a mixture of shales and sandstones, the oldest rock of the Mesozoic Era in this area. The red color in a rock often indicates an oxygen-rich environment. The Moenkopi is no exception; it is terrestrial in origin and you CAN find animal tracks, though I'm not usually so lucky.

The most recent Peleozoic strata here are the fossil-rich Kaibab limestones, a former coral reef. It has a distinct weathering pattern, forms the cliffs below the falls, and may be stained by the overlying Moenkopi. You may have seen a cleaner looking Kaibab as the top layer at the South Rim of the Grand Canyon.

At the base of the falls you will find the third sedimentary rock formation - the crossbedded Coconino Sandstone, a beautiful wind deposited layer. The Coconino forms one of the major cliffs in the Grand Canyon and is exposed in many canyons throughout Navajo and Coconino County.

The other rock in the area is igneous basalt which originated from the base of Merriam Crater, 10 miles to the south. Below the falls, you can see where the lava, once it reached the river about 150,000 years ago, flowed down the canyon.

1. Rough road for an early field trip.
2. Just above the falls, river has 'fluted' the basalt riverbed. Kids love exploring this.
3. The sediments can be high in clay. Your shoes will stick!
4. As with many clays, when dried, these natural 'tiles' form.

1. Notice the parallel fractures. The students should observe that there has been no offset to the layers, so these are considered faults rather than fractures.
2. The falling water, erodes plunge pools. Some of the pools are connected.
3. There is ample evidence of the vulcanism that has affected the San Francisco volcanic field 1.6 million years. (Nations, 57)
4. Along the cliffs to the south, you can find fossils. Please leave all findings; this is property of the Navajo. You are a guest.

1. Two fossils.
2. As the falls digs under itself, portions of the limestone break off. This means the cascade is eroding upstream.
3. View from the ramadas. Note that the terraces are aligned with the fractures. The buttes are part of the Moenkopi. The underlying Kaibab Limestone is stained red.

1. There is the basalt on the south rim and the sedimentary rock on the north. In the distance you will notice basalt on BOTH side of the canyon, showing how the flowing lava used this canyon as a conduit in its journey.
2. Below the falls are HUGE fallen blocks. Have your kids determine what kind of rock this is. (Bring your hydrochloric acid!) Why are those rocks in the middle of the river rounded? What was their source? Note the adventurous student (in a white t-shirt) high on the canyon wall.
3. Take time to view the signs of those who live here or pass through - a great blue heron and a ??? Have your kids be quiet and listen. Good journal time!
4. The basalt cliffs on the south side are coated with a mud mist. In places, the rains have cleaned the cliffs.

1. Walking along the Coconino Sandstone ledge below what would be the waterfall. This rock has crossbedding.
2. Beautiful!
3. You can examine the sediment grains if you bring your hand lens.
4. More beauty.

1. Intricate driftwood patterns.
2. The Sunrise Middle School students in the basaltic fluting above the falls.

Introduction | Verde Salt Mine | Schnebly Hill | Overnight | Cinder Cones | Montezuma's Well