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- 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. - Survival in Extremes
Notice the different patterns of vegetation around you. Volcanic eruptions alter plant communities, destroying some, creating new habitat for others, and changing growth rates for those remaining. On the lava flow in front of you most soil has come from wind-blown material that collects in cracks and holds water. Consequently, soil and moisture vary dramatically across the flow. And, since seeds blow in, colonization is quite random. Classic succession with lichens breaking down rock into soil, and plants returning in predictable sequence is not occurring here. As plants return to the barren landscape, so do the animals that use the plants for food and shelter. Many animals that live here are nocturnal. Some take shelter in the lava flow. Others blend in so well with their surroundings that they are difficult to spot. A careful observer may see evidence such as tracks or droppings. - Surveyor Lunar Rover Prototype
Description: In 1964, two lunar rover prototypes were tested on the Bonito Lava Flow to determine which had the best trafficability on the lava. The lava tore the tread from the Bendix prototype (shown here), and both prototypes were ultimately dropped because of poor field-test results. Collection: USGS Open-File Report 2005-1190, Figure 009. - Surface Currents
Looking beyond the lava and spatter in front of you, and just beyond the line of trees, can you see a reddish hill? This is an agglutinate mound or pile of welded pyroclastic material. In the early stages of the eruption, a cone began to form next to a major explosive vent. The cone became armored by welded deposits. Then a column of dense magma broke through the base of the cone, causing the upper part of the cone to collapse onto the top of the flow. The slumped pieces were then rafted away by the flowing lava. You are looking at a large piece of an early-stage cone of Sunset Crater. Perhaps within weeks or days after breaching, the cone was rebuilt, creating the symmetrical cone of Sunset Crater we see today. Any remnants of the earlier cone lie buried beneath tons of cinder. - Sunset Red Smudged Bowl
Description: Sunset Red Smudged bowl. Dimensions: 7.3 cm (Ht), 12.8 cm (rim diam). Collection: On display at the Sunset Crater Volcano National Monument Visitor Center (catalog card). - Suiting Up
Description: Gene Shoemaker, Jerry Harbor, or Gene Phillippi suiting up to test equipment in Sunset Crater Volcano National Monument. Collection: USGS Open-File Report 2005-1190, Figure 016g. - Squash Blossom Necklace, Close-up
Description: Navajo silver and turquoise squash blossom necklace from the Museum of Northern Arizona gift shop. The necklace dates to the 1930s or 1940s, and has three blue turquoise stones in the hand-stamped naja, or the crescent pendant portion of the necklace and 20 silver squash blossoms evenly distributed on each length of the necklace (10 on each side). Dimensions: 16 in (L), Pendant-2.5 in (W), 2.25 in(L). Collection: On display at the Sunset Crater Volcano National Monument Visitor Center (catalog card). - Squash Blossom Necklace
Description: Navajo silver and turquoise squash blossom necklace from the Museum of Northern Arizona gift shop. The necklace dates to the 1930s or 1940s, and has three blue turquoise stones in the hand-stamped naja, or the crescent pendant portion of the necklace and 20 silver squash blossoms evenly distributed on each length of the necklace (10 on each side). Dimensions: 16 in (L), Pendant-2.5 in (W), 2.25 in(L). Collection: On display at the Sunset Crater Volcano National Monument Visitor Center (catalog card). - San Francisco Peaks
Composite or stratovolcanoes have sharp peaks or less steep sides. Mount St. Helens, Mount Fuji, and the San Francisco Peaks, seen here in the distance, are examples of this classic volcano type. - Ropes and Clinkers
You are now on the southern edge of the Bonito Lava Flow. Magma, periodically relieved of gas pressure, squeezed out of the base of the cone as glowing liquid lava, creating a structurally complex flow covering 2 sq miles (5 sq km). Lava flows tend to form either jagged blocks, known as aa (ah-ah), or a smooth, ropey surface of pahoehoe (pa-hoy-hoy). Flows usually start as pahoehoe, thin and runny. As the lava cools and becomes more thick and pasty, it can change into an aa flow. The Bonito Flow is mostly aa lava. When aa is forming, cooled, hardened blocks - sometimes called clinkers - are rafted along the surface of moving lava, making clinking noises as they tumble into each other. Although its structure is complicated, the flow’s composition is uniform throughout. The lava and cinders around you, whether black or red, ropey or jagged, are basalt. - Preparing to Test Equipment, 1964
Description: In 1964, the first field tests using NASA space suits took place on the Bonito Lava Flow and the deep bordering cinder. Here, the crew poses alongside the equipment truck, with the Bonito Lava Flow behind them. Collection: Sunset Crater Volcano National Monument. - Power to Symbolize
- Penstemon
Along the perimeter of the flow, a unique microhabitat for plants exists. In places, water collects on the surface of the flow and is then channeled through fractures to the edge where it locally benefits plants. White-barked aspen trees grow around the perimeter of the flow and along fracture systems. In area of deep cinder, like the dunes in the distance to your left, specialized plants have evolved. The Sunset Crater penstemon evolved new traits which allow it to live on cinder soils but also make this endemic plant dependent on this habitat. It cannot survive elsewhere. - Paricutin
Volcanic eruptions may seem destructive but they are among the beneficial forces of a living planet: forces that build mountains, create oceans, and provide for live. Only when our planet has finished cooling will there be no volcanoes. Then, Earth will be a dead planet much like Mars. The eruption of Parícutin in Mexico, 1943, is considered the modern day equivalent of the Sunset eruption. - Our Dynamic Earth
Alpine slopes, forests, and grassy parks disguise the fiery, molten, and often explosive history of this region’s landscape. But here, amidst the Bonito Lava Flow and Sunset Crater’s cinder fields, the land’s volcanic origin is revealed in stunning clarity. As you walk the trail, use this guide to explore the powerful forces – rapid and violent, slow and patient – that continually shape our planet. These forces all affect our lives and provide for life in ways we may not realize.