This weekend we took the kayaks to the Narrows of Upper Lake Mary. The lake has maintained boat ramps for motorized and unmotorized boats. The ramp at the narrows is very shallow and most suitable for launching light craft. What started as a day with slight clouds and damp ground from a storm the previous evening, promised to give us enough time for a cruise around the area before the next storm could move in. This is the monsoon season of Arizona, and prone to lightning, thunder and heavy downpours, so we started early.
In 1910 a devastating wildfire tore through Idaho and Montana. In just two days’ time, the Big Blowup consumed almost three million acres of forested hillsides. Drought and high winds created the perfect conditions for a firestorm. The National Forest Service had recently been created, but fighting the fire required additional help from the US Army and the local miners. At last, a cold front brought a rain storm that put the fire out. Eight-nine lives were lost and the horrifying stories of the survivors motivated the country to create a fire suppression policy.
For most of the last century, the Forest Service put out almost every fire. The result, unfortunately, has been severely increased forest density. The first settlers in northern Arizona described the forest as possible to ride a horse through at a full gallop.
Today riding at a gallop through the woods around Flagstaff would not be advisable. According to turn of the century reports from the early 1900’s, northern Arizona was mixed conifer forest with grassy undergrowth and large, open areas. Because of the distance between the large old growth trees, when a wildfire occurred, it burned along the ground, not in the crown of the tree as today. This allowed the trees to survive a fire, whereas today, everything is killed.
You can see a burned off area at the top of this hill, with standing snags. The area below the hill was saved by fire-fighting efforts.
Arizona has a dry climate. Arizona has experienced long drought periods in the past. When the Ponderosa Pines are distressed by lack of moisture, they are prone to the Pine Bark Beetle. In 2010, 9.2 million acres (Out of 749 million acres of forest land in the United States) of tree mortality was caused by insects and disease. 74 % of that damage was done by the Bark Beetle. Once these stands of trees die, they are tinder waiting for the next lightning strike, careless camper, or tossed cigarette.
The problem is compounded by the number of homes built in the interface area between the forest and the urban areas. Firefighters are put at risk to save homes from the fast-moving fires. Much has been learned about caring for our wild lands, and one of the projects now underway is 4FRI. This is the Four Forests Restoration Initiative, working to restore the structure, pattern and composition of fire-adapted ecosystems, which will provide for fuels reduction, forest health, and wildlife and plant diversity. 4FRI aims to implement comprehensive restoration over the next twenty years, including thinning of predominantly small trees across one million acres, and safe controlled burning and natural fire management on much of the landscape.
Bark Beetle-downed trees
Slash piles ready for burning
A controlled burn
Hopefully 4FRI is a solution for implementing landscape-scale forest restoration. It is a problem that will take twenty years or more to solve, with new fires happening each year. Home owners in the urban interface areas attempt to clear areas around their homes, and create emergency plans for escape should a fire start.
Arizona is a geological laboratory because the natural forces in play are so visible. Erosion is a general term for the weathering of rocks and the transportation of them. The forces of erosion are gravity, ice, water and wind.
The San Francisco Mountain in Flagstaff is a strato-volcano in the midst of a volcanic field of over 600 smaller volcanos. This largest volcano is now 12, 633 feet in elevation, but it is estimated it reached 16,000 feet before a sideways eruption or glacial erosion, or both, collapsed or carved out the northeastern side of the mountain.
You can see green lichen growing on this large basalt boulder at the base of Mount Elden in Flagstaff. Weathering and erosion from the lichen, rain, snow, and freezing winter temperatures have and cracked the boulder in half.
In the mesa shown below, you can see how the soft sedimentary layers at the top have been weathered away by wind and water and gravity has piled it around the bottom.
Wind is a powerful force in erosion as you can see in the photo of Tsegi Canyon below where it hollows out the sedimentary rock.
Water helps to carry away the debris weathered from the higher elevations and the grit and sand in the water help to erode more rocks as it passes.
The classic Arizona erosion example is the Grand Canyon of the Colorado River.
Because Arizona is arid by nature, we are tempted to think it has no water. Since ancient times. residents of this desert land have been ingenious in harnessing the water resources needed for life. As it was for the ancients, our main renewable resource for water is surface water in streams.
For almost 1500 years the Hohokam people inhabited central Arizona, farming near the Gila and Salt Rivers. In about 600, the Hohokam began to dig canals up to twelve feet deep to bring water to their 110,000 acres of fields.
Their amazing irrigation system made it possible to support a population of about 80,000 people. We do not know what finally disrupted their civilization in about 1450, but they left petroglyphs on hilltops throughout the region. Their descendants live on as the Tohono O’odham Nation.
In the 1870s, settlers to the central valley followed the lines of the ancient canals and brought water from the same Salt River to their own fields. Those canals are no longer in use, but newer canals criss-cross the valley bringing water from the river and from new projects. Arizona has developed one of the most sophisticated water management programs in the world. (The Arizona Experience)
Beginning in the early 1900s, Arizona began building a series of dams along the streams and creeks of the state. Lakes behind these dams provide recreational use as well as water supplies for drinking water, irrigation and industry.
As it was for the ancient people, the surface water today is not dependable season to season or year to year. Additional resources currently are Ground Water, Colorado River Water, and Effluent. Water from the Colorado River is brought into the middle of the state with the Central Arizona Project, CAP, and used to fill the lakes and recharge the groundwater. With careful management, Arizona is not so dry after all.