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- Why are Volcanoes Here?
Most volcanoes are found along tectonic plate boundaries where continents and seafloors collide or move apart. We are far from a plate boundary; consequently, geologists debate why volcanoes occur here. One theory proposes that the North American plate is moving over a stationary “hot spot.” But this theory does not explain why there are young volcanic fields all along the southern margin of the Colorado Plateau and then east to New Mexico and Oklahoma. Another more accepted theory focuses on a disruption in the flow of Earth’s mantle at the boundary between the Colorado Plateau, where the Earth’s crust is very thick, and the Basin and Range region (to the south and west), where the crust is very thin. At this transition, heat from the mantle rises and melting occurs. Ancient faults, activated by stretching of the North American plate (which has created the Basin and range and is extending into the Colorado Plateau), serve as pathways for magma to move to the surface. - Taking Root
When the lava flowed and the cinder cone formed, all plant life within a several mile radius was destroyed. The oldest ponderosa pine trees here today are about 400 years old and are probably not the first generation to return. Unlike Hawaii where abundant moisture promotes plant growth soon after eruptions, precipitation here averages only 16 inches (41 cm) a year. Furthermore, soil is sparse in this dry climate where water limits plant life and organic material breaks down slowly. Notice the massive trailing root system of this dead tree. Trees growing on these cinder slopes face extraordinary challenges in finding anchor in loose, unstable cinders and in capturing water as it drains rapidly through them. Notice also how this tree spiraled as it grew. Ponderosa pines grow either straight or dextrally (spiraling to the right). Spiral growth reduces the overall strength of a tree but increases its flexibility. The spiral grain also provides an even distribution of water from a single root to all of the needles and of nutrients from a single branch to all the roots. In a straight tree, wind-damaged branches or damaged roots would deprive water and nutrients to the roots directly below and branches directly above. By spiraling, this tree was better adapted to the stresses of its environment: lack of water, high winds, and occasional heavy snow. But it wasn't able to remain anchored when its roots were exposed by erosion from foot traffic. - Miniature Volcanoes
On the slope below you is a small spatter cone. Spatter cones, or hornitos (“little ovens” in Spanish), form when lava is forced up through an opening in the cooled surface of a lava flow. They are “rootless,” fed by the underlying flow rather than a deep magma conduit. Can you picture fluid fragments of liquid spurting upward, flattening, congealing, and mounding around the opening? Can you imagine approaching an erupting spatter cone? Unique artifacts found nearby – corn casts in lava rock – suggest people did. Experiments conducted in Hawaii demonstrated that “corn rocks,” like the one on display in the visitor center, can form when ears of corn are covered by fluid blobs of spatter. It appears people intentionally ventured close to an active hornito, maybe this one, to leave corn – perhaps as an offering. More than 50 rocks with corn casts have been found in homesites attributed to the local Sinagua cultural tradition. - Undercurrents
Beneath the lava you now stand on are perhaps dozens of caves. As lava flowed, the top surface cooled first due to contact with air. A hardened crust formed. Meanwhile, rivers of lava continued flowing below, periodically breaking through the crust to form the spatter cones you saw earlier. When the flows ceased, the remaining lava drained out the downhill end of the crusted-over channels, leaving behind tube-like caves. Most of these caves were sealed with hardened lava and have no openings to the surface. A collapse created the opening you see here. - Debate
- Introduction to the Trail
A sculpture garden of extraordinary shapes and forms awaits you on this walk through the lava flow and cinder fields. This moderate (1 mile, 1.6 km) trail has rough surfaces and takes you through lava flows and cinder barrens to the base - not to the top - of Sunset Crater. In person, you need water and sturdy footwear. There is also an alternate 1/4-mile (0.4 km), easy, wheelchair accessible paved loop.
Throughout this virtual trail guide, you will find benchmark pages and interpretive station pages. The benchmarks are those numbered in the guidebook, and the interpretative stations are text and photo displays placed along the trail itself. - ORV
- The Birth of a Mountain
- Life and Landscape Transformed
- As Powerful as a Volcano
- Volcanoes
- Frozen in Time
- Changes to Come
- Power to Symbolize
- Give and Take
From the earliest times, people have enjoyed the long-term benefits of volcanic eruptions. People journeyed long distances to volcanic areas to gather materials for their daily lives, including important minerals, raw materials like obsidian for tools, and building supplies. And always, in return for these benefits, people have paid a high short-term price in the form of volcanic disasters. Our culture influences how we forecast events, choose to prepare and adapt to catastrophes, and how we explain our world and its phenomena. Some of us look to science, some to religion, and some to traditional knowledge. It is not surprising that worldwide, when people live near volcanoes, they often develop related rituals and belief systems. This eruption was a significant event in the lives of the native peoples of the Southwest, and today all of the region’s American Indian groups consider this a scared landscape.