Wry Heat

Scamming the Media

Last week we read or heard stories that said “Arizona’s global warming pollution increased by 61 percent since 1990, according to a new analysis of government data released today by Environment Arizona.” The “pollution” referred to is carbon dioxide.

Those stories are a good example of Mark Twain’s observation: “If you don’t read the newspaper, you’re uninformed. If you read the newspaper, you’re mis-informed.”

The press release by Environment Arizona spun their findings to maximize sensationalism. It is clear from the media stories, that most reporters either did not read the full study, or chose to report only the headline-grabbing, but misleading statistic.

The study itself says that Arizona per capita carbon dioxide emissions are below the national average. It also says that Arizona per capita emissions have decreased by 6% since 1990. Why didn’t that last statistic make the headlines?

Along with statistics gleaned from the EPA, Environment Arizona spouts the tired propaganda of global warming alarmists such as: “Temperature increases of only 3.6° F higher than pre-industrial levels could have catastrophic consequences—and 1.4° F of warming has already occurred.” Regular readers of this blog will know that we are currently in an interglacial period of an ice age that the “normal” temperature of this planet is about 18 F warmer than it is now, and that atmospheric concentration of carbon dioxide for most of the planet’s history has been 3- to 10 times higher than now. (See chart below, see also my seven-part series on geological history, Natural Climate Cycles, and other blogs in the climate change category.)

Environmental Arizona claims that carbon dioxide is the “leading global warming pollutant.” But carbon dioxide is insignificant compared to water vapor as a greenhouse gas. The term “pollutant” is both emotive and erroneous. The dictionary defines a pollutant as “a harmful chemical or waste material discharged into the water or atmosphere.” Carbon dioxide, however, is vital to life. Without it, there would be no life on this planet, and geological history shows that life is more abundant and robust at concentrations above 1,000 ppm, three times the current concentration.

Environment Arizona is one of the many branches of Public Interest Research Groups (PIRG), founded by Ralph Nader in the 1970’s as a consumer advocacy organization. PIRG seems to have morphed beyond that cause.

In researching this article, I found some stories which show that PIRG has been less than honest in its fund raising and advocacy.

A Boston Globe story (http://www.jeffjacoby.com/4818/stopping-pirgs-scam ) says: PIRGs collect huge amounts of money through a dishonest scheme called a “negative checkoff.” Each semester, students are automatically charged for a “donation” to PIRG of several dollars; the charge is included in their tuition. It isn’t mandatory, but a student who is unwilling to finance PIRG’s left-wing political agenda must affirmatively refuse to pay. PIRG figures that many students — and many parents — won’t realize the fee is optional or even notice it on the bill. Sure enough, amid the tumult of each new semester, most students just pay up — and PIRG grows ever richer. In New Jersey last year, NJPIRG used the negative checkoff to milk students for an estimated $200,000. In Florida, the take was about $320,000. In Massachusetts, $400,000. (In some states, the PIRG “donation” is mandatory. New York students were euchered out of $800,000 — forced to subsidize NYPIRG’s political objectives whether they agreed with them or not.)

A recent report by the Reason Foundation (a libertarian think tank) accuses PIRG of issuing misleading reports on transportation: “The always anti-privatization Public Interest Research Group has just released its second report criticizing the growing trend of state governments turning to long-term public-private partnership (PPP) deals to attract private investment into their ailing highway systems. The worst distortion of what’s going on is the way the PIRG report blurs the distinction between leases of existing toll roads and similar long-term deals that create brand new (and much-needed) toll roads via private capital investment.” (http://reason.org/blog/show/pirgs-misleading-report-on-pub)

The Competitive Enterprise Institute today (April 6, 2000 ) accused the U.S. Public Interest Research Group of misleading the American public about the ramifications of global warming. U.S. PIRG’s new report, Storm Warning: Global Warming and the Rising Costs of Extreme Weather, is yet another attempt to link global warming to events where there is no link to be made. http://cei.org/gencon/003,02595.cfm

Yes, I realize that stories detrimental to PIRG come mainly from more conservative sources, perhaps because more liberal publications don’t usually print the stories.

The conclusion I draw from this affair is that many news organizations publish by press release without checking the full story and the potential biases of its source.

Of all the mammals in the desert, the kangaroo rat is perhaps the best adapted to arid conditions: it never needs to drink, nor eat fresh vegetation; it can metabolize water directly from dry seeds.

The diet is almost exclusively seeds, and it prefers seeds high in carbohydrates rather than seeds high in fat or protein. That’s because metabolizing fatty seeds produces heat, and metabolizing protein-rich seeds requires more water to get rid of nitrogen-rich waste products.

The K-rat stores seeds in its burrow where they absorb any humidity, thereby giving the rat some extra moisture. The K-rat has no sweat glands through which to lose water.

The kangaroo rat minimizes moisture loss during respiration with its specialized nasal passages which function as counter-flow heat exchangers. These passages warm the air during inhalation, then cool the air and extract moisture during exhalation.

The kangaroo rat can conserve water by producing urine about 5 times more concentrated than human urine. The rat also produces very dry feces pellets with about one-fifth the water content of a white lab-rat’s pellets.

The kangaroo rat is 4- to 5 inches long with a tail up to 10 inches long. It prefers to hop on its hind legs. It can jump 10 feet and change direction immediately upon landing, something that helps it avoid nocturnal predators.

Although the rat has tiny external ears, the middle ear chamber is highly developed and may be bigger than the braincase itself. This allows the rat to hear low intensity and low frequency sounds such as an owl flying or a rattlesnake ready to strike. This, together with its ability to jump 10 feet, helps it avoid predators.

The December issue of Consumer Reports (page 54) contains an article on Bisphenol A (BPA) which is used in plastic bottles and food-can liners. CR tests found BPA in almost all canned food tested. The question is how much, if any, has adverse health effects.

The FDA currently puts the daily upper safe limit of exposure to BPA at 50 micrograms per kilogram of body weight. Consumer Reports says that standard is based on experiments done in the 1980s and that more recent tests show abnormalities in animals at much lower exposures.

Consumer Reports recommends that manufacturers and government “should act to eliminate the use of BPA in all material that come into contact with food.” Consumer Reports fails to cite the new studies referred to.

The Statistical Assessment Service (STATS) at George Mason University takes Consumer Reports to task:

“Consumer Reports made so many factual errors in presenting its data on BPA in canned goods that no-one could have possibly read the actual research. A call for a ban on the chemical puts the public at risk from deadly food borne pathogens.”

“Consumer Reports have come out with a purported investigation into the chemical Bisphenol A that shows scant familiarity with any of the risk assessments of the chemical. Given that BPA is used to prevent food spoilage in cans, and given that food spoilage can lead to bacterial infection putting people at risk from botulism, and given that there is no safe and effective alternative as yet for BPA, these errors and exaggerations and omissions are not trivial. Consumer Reports seems to be oblivious to the extensive research on BPA carried out by the European Union, the Environmental Protection Agency, and others, all of which refutes the magazine’s claims about the chemical. ”

The STATS article goes on to list specific reasons why they think CR did a bad job. The STATS article also provides links to recent research from Europe, Japan, Canada, Australia, and the U.S. which conclude that BPA does not pose a hazard.

Read the STATS article and make up your own mind. http://tinyurl.com/yg5zhrw

Note: I am a subscriber to Consumer Reports

Mice will eat just about anything, but most prefer plant parts. The grasshopper mouse, however, is a ferocious carnivore. It eats grasshoppers, beetles, spiders, centipedes, millipedes, worms, lizards, scorpions, snakes, and other mice. It hunts like a cat and defends its territory by howling – it is the mouse that roars.

There are several species and most inhabit the grasslands of the great plains, but at least one species is a desert dweller. The Northern Grasshopper mouse has a range from Canada to Mexico, and California to Minnesota; the Southern Grasshopper mouse has a range that includes parts of Nevada, Arizona, New Mexico, and Texas. The southern species is gray-brown- to cinnamon colored with a short white-stripped tail. Most grasshopper mice are relatively stout compared to other mice. The head and body is 3.5″- to 5″ and the tail is 1″ to 2.5″ long.

Usually a male-female pair live together and defend a territory. It marks the territory with musk.

Grasshopper mice have very strong jaw musculature required for killing prey. And they learn quickly how to deal with various prey. One observer describes how the mouse dealt with a 3-inch scorpion in Arizona: ” The mouse would first nip the tail so that the stinger was ineffective. It would then stand the scorpion on end, holding it with its front paws, and methodically eat the writhing creature head first.”

The grasshopper mouse is a nocturnal hunter, a good climber, and active year round. In some areas, scorpions account for almost their entire diet, which might be surprising because the mice are not known to have any immunity to scorpion venom.

These mice will eat seeds, grasses, and grains, and cache them, like other mice, but about 90% of their diet is animal matter. The strangest part of their diet is sand. Biologists think the mice eat sand to aid in digestion, just like some birds ingest gravel. And that’s not all that is strange about their digestive system. As described in an article by Mary Ingle: “A pouch attached to the underside of the stomach opens into it via an aperture too small for large food particles to pass through. The pouch contains all of the gastric glands that contribute to the breakdown of food and are normally found in the stomach of other mammals.” Ingle speculates that the pouch exists because the insect diet would be too rough and damaging for delicate gastric glands to function normally.

The grasshopper mouse digs four kinds of burrows: nesting, retreat/sleeping, caching, and the bathroom.

The mice have several vocalizations. You may have heard their territorial proclamation and mistaken the high-frequency sound for that of an insect. So now, when you are out at night, listen for the mouse that roars.

For a video of a battle between a grasshopper mouse and a very large centipede check here: http://tinyurl.com/ylyme9w Note that centipedes are venomous.

On Tuesday, Oct. 27, my westside neighborhood experienced approximately 30 short power outages during the very windy day and evening. Each would last from 30 seconds to five minutes. That made work on a desktop computer very difficult. By the way, my neighborhood has all underground utilities.

I inquired of TEP to see what was happening and what they were doing about it.

This morning I received a call from TEP spokesman Joseph Barrios. He said that overhead lines leading into the neighborhood carry both high-voltage transmission lines and lower-voltage distribution lines. Slack in the lines caused them to touch and short out, tripping circuit breakers. The breakers would automatically reset.

Barrios said that if this happens more than four times, the TEP crews search out the cause. Apparently over time, the lines stretch, resulting in too much slack. Barrios said that crews have now tightened the lines and installed “separators” which hopefully will prevent future problems, at least for a while.

Although the power outages were inconvenient, I appreciate that TEP crews got to work to identify the problem and that Mr. Barrios telephoned me with an explanation.

If you have been reading my series on the geological history of Arizona, you may have noticed that the Earth has plunged into an ice age every 145 million years or so. But wait, haven’t ice ages occurred more frequently? No. There is confusion because the term “ice age” is frequently misused by Journalists (and often by many geologists) when they really mean glacial epoch. So what is the difference? An ice age consists of several glacial epochs separated by warmer interglacial periods.

A glacial epoch is a time during which much of the earth’s surface is covered by glaciers. The frequency and duration of glacial epochs are related to the position and orientation of the earth with respect to the sun. The location of the continents also influences the severity of glacial epochs because continents confine ocean currents. For the last 500,000 years of our current ice age, the glacial epoch-interglacial cycle has had a periodicity of 100,000 years. Prior to 500,000 years ago, the glacial-interglacial cycle was 41,000 years. We are now enjoying an interglacial period.

Ice Ages

Our current ice age, called the Pleistocene, started about 2.6 million years ago. Ice ages are related to the position of the solar system within the galaxy. Ice ages have occurred whenever the solar system passes through one of the five known spiral arms of our galaxy, which occurs at intervals of about 145 million years (± 10 million years).

What do stars have to do with ice ages? The hypothesis, greatly simplified is this: Star density within the spiral galactic arms is much greater than in the galactic disk, hence, the flux of cosmic rays is much greater. Cosmic rays penetrating our atmosphere collide with molecules in the air and produce ionization. The ionized particles attract water and produce more clouds than normal. The clouds reflect sunlight which causes cooling. There is both observational and experimental evidence to support this hypothesis. Cosmic ray flux can be deduced from the so-called cosmogenic nuclides, such as beryllium-10, carbon-14, and chlorine-36, as measured in ancient sediments, trees, shells, and in meteorites. The geologic reconstruction of temperature is based on oxygen-18 isotopes from fossils and cave stalagmites. Also, glaciation leaves distinctive deposits and land-forms.

In the graph below, the top panel shows several calculated cosmic ray flux reconstructions. In the bottom panel, that curve is flipped to represent the cooling effect. Notice that the cosmic ray flux coincides with the geologic reconstruction of ice ages. (The green “residual” curve represents the mathematical variance between models and observations.)

Glacial Epochs

Glacial epochs within ice ages seem to be controlled by the relationship of the earth to the sun. There are three main variations called Milankovitch cycles (after Serbian geophysicist Milutin Milankoviæ who first calculated the cycles): Orbital Eccentricity, Axial Obliquity, and Precession of the Equinoxes. All these cycles affect the amount and location of sunlight impinging on the earth. The following explanation of the cycles are summarized from The Resilient Earth:

Eccentricity cycle of 100,000 years

Earth’s orbit goes from measurably elliptical to nearly circular in a cycle that takes around 100,000 years. When Earth’s orbital eccentricity is at its peak (~9%), seasonal variation reaches 20-30%. Additionally, a more eccentric orbit will change the length of seasons in each hemisphere by changing the length of time between the vernal and autumnal equinoxes. The variation in eccentricity doesn’t change regularly over time, like a sine wave. This is because Earth’s orbit is affected by the gravitational attraction of the other planets in the solar system.

Where we are now: Earth’s current orbital eccentricity is 0.0167, which is relatively circular. Presently, Earth’s distance from the Sun at perihelion, on January 3rd, is 91 million miles. Earth’s distance from the Sun at aphelion, on July 4th, is 95 million miles. This difference between the aphelion and perihelion causes Earth to receive 7% more solar radiation in January than in July. Currently, Earth’s orbital eccentricity is close to the minimum of its cycle. There is also a weak variation cycle of 413,000 years.

 Axial Obliquity cycle of 41,000 years

 The second Milankovitch cycle involves changes in obliquity, or tilt, of Earth’s axis which varies on a 41,000 year cycle from 22.1° to 24.5°. The smaller the tilt, the less seasonal variation there is between summer and winter at middle and high latitudes. For small tilt angles, the winters tend to be milder and the summers cooler. Cool summer temperatures are thought more important than cold winters, for the growth of continental ice sheets. This implies that smaller tilt angles lead to more glaciation.  Where we are now: Currently, axial tilt is approximately 23.45 degrees, reduced from 24.50 degrees just a thousand years ago.

Precession cycle of 23,000- 25,800 years

The third cycle is due to precession of the spin axis. As a result of a wobble in Earth’s spin, the orientation of Earth in relation to its orbital position changes. This occurs because Earth, as it spins, bulges slightly at its equator. The equator is not in the same plane as the orbit of Earth and other objects in the solar system. The gravitational attraction of the Sun and the Moon on Earth’s equatorial bulge tries to pull Earth’s spin axis into perpendicular alignment with Earth’s orbital plane. Earth’s rotation is counterclockwise [viewed from above the north pole]; gravitational forces make Earth’s spin axis move clockwise in a circle around its orbital axis. This phenomenon is called precession of the equinoxes because, over time, this backward rotation causes the seasons to shift.

The full cycle of equinox precession takes 25,800 years to complete. Due to the eccentricity cycle, Earth is closest to the Sun in January and farther away in July, but the northern hemisphere is tilted away. Due to precession, the reverse will be true 12,900 years from now. The Northern Hemisphere will experience summer in December and winter in June. The North Star will no longer be Polaris because the axis of Earth’s rotation will be pointing at the star Vega instead.

Individually, each of the three cycles affect insolation patterns. When taken together, they can partially cancel or reinforce each other in complicated ways.

Glacial epochs can be triggered when tilt is small, eccentricity is large, and perihelion, when Earth is closest to Sun, occurs during the Northern Hemisphere’s winter. Perihelion during the Northern Hemisphere winter results in milder winters but cooler summers, conditions that keep snow from melting over the summer. Deglaciation is triggered when perihelion occurs in Northern Hemisphere summer and Earth’s tilt is near its maximum. There are other factors which act to enhance the forcing effects of the cycles. These include various feedback mechanisms such as snow and ice increasing Earth’s albedo, changes in ocean circulation and enhanced greenhouse heating due to increased CO2 and water vapor concentrations.

Solar Cycles

The sun itself goes through cycles of solar intensity and magnetic flux. When the cycles are in a strong phase, the amount of cosmic rays entering the atmosphere is reduced, there are fewer clouds to block the sun, so it is warmer. When solar cycles wane, as is beginning to happen now, more cosmic rays enter the atmosphere and produce more clouds which block the sun, so it becomes cooler.

The number of sunspots (hence magnetic flux) varies on an average cycle of 11 years. There are also 87-year (Gliessberg) and 210-year (DeVriess-Suess) cycles in the amplitude of the 11-year sunspot cycle which combine to form an approximately 1,500-year cycle of warming and cooling. See : Natural Climate Cycles. So far, there is no evidence that atmospheric carbon dioxide has anything to do with the cause of ice ages or glacial epochs. (See Al Gore’s Favorite Graph). The graph below shows the correlation between temperature and sunspot cycles, and only coincidental correlation with carbon dioxide.

References:

Hoffman, D.L. and Simmons, A., 2008, The Resilient Earth, an online book: http://theresilientearth.com.

 Shaviv, N.J., 2003, The spiral structure of the Milky Way, cosmic rays, and ice age epochs on Earth, New Astronomy 8, 39.

 Shaviv, N.J., and Veizer, Jan, 2003, Celestial Driver of Phanerozoic Climate, GSA Today, July 2003.

Veizer, Jan, 2005, Celestial Climate Driver: A Perspective from Four Billion Years of the Carbon Cycle, Geoscience Canada, V. 32, no. 1.

The Cenozoic era represents the most recent 65 million years. (See the geologic time chart for the subdivisions.) Arizona was squeezed, then stretched; steamed and frozen.

Construction of the Rocky Mountains, volcanism, and emplacement of our major copper deposits, all of which began in Cretaceous time, continued in the Cenozoic until about 40 million years ago. During this time, the oceanic crust of the Pacific Ocean was being subducted beneath the westward-moving North American continental plate. The resulting compression caused southern and western Arizona to be topographically higher than the Colorado Plateau, the opposite of current topography.

By about 20 million years ago (mya) Arizona was covered with thousands of feet of volcanic rocks, locally punctured by calderas. Sometime between 30- and 20 million years ago the north American tectonic plate overrode a spreading center called the East Pacific Rise. This area is similar to the spreading center of the Mid-Atlantic ridge that gradually separated Africa from South American, and Europe from North America. Today, this western spreading center runs up the Gulf of California and separates Baja from mainland Mexico. It is also the driver of the San Andreas fault in California. By over-riding the spreading center, the tectonic regime changed from compression to extension. Arizona began to be pulled apart to form the Basin and Range physiography of today.

Arizona is divided into three physiographic provinces: the Colorado Plateau in the northeast, a transition zone extending from northwest to southeast Arizona (the Mogollon Rim), and the Basin and Range province in the south and west. Currently the Basin and Range extends from the Snake River plain in Idaho, through Nevada and Arizona, into Mexico.

Initially, crustal extension along a northeast-southwest axis was characterized by widespread normal faulting and fault-block rotation. Movement occurred along high-angle normal faults which at depth flattened into low-angle detachment faults (see figure below from Spencer and Reynolds). Displacement along these faults is several tens of kilometers. The present location of the Tucson Mountains is a direct result of this extension. (See Tucson Mountain Chaos) Later extension resulted in high-angle faults which bound our valleys and make some of the valleys as much as 15,000 feet deep to bedrock.

   This extension sometimes made the life of geologists very interesting when exploring for porphyry copper deposits, because some of those deposits were cut and fanned out like a deck of cards. Finding all the pieces took some geologic detective work. For instance, the Twin Buttes mine, the Mission-Pima mine, and the San Xavier mine south of Tucson, together with buried mineralization between them, represent slices of a once-intact mineral deposit. The Sierrita mine, located on the opposite side of a major fault from the others is still intact.

Middle Cenozoic veins host gold, silver, and base-metal deposits. Copper-gold mineralization is associated with the detachment faults. Manganese and uranium deposits occur in the basins resulting from the extension.

Volcanic activity resumed 2- to 3 million years ago with eruption of basalt which produced flows and cinder cones. The rocks of the San Francisco volcanic field near Flagstaff, the Springerville-Show Low field, the San Bernardino field east of Douglas, and the Pinacate field in Mexico are examples of this episode.

The Grand Canyon was formed during the late Cenozoic. The Colorado River existed as long ago as 20 million years, but it flowed to the northeast across the Colorado Plateau. Crustal extension disrupted this flow pattern and caused the formation of several lakes similar to the Great Salt Lake (i.e., the lakes filled by interior flow from rivers that did not flow to the sea). As the Gulf of California opened, drainage into the Gulf gradually worked its way north and eventually “captured” the interior drainage of the Colorado River system. The lower river began its development about 5.5 mya; by 1.2 mya it was at its present grade in the western Grand Canyon.

Climate in the early Cenozoic continued to be hot and steamy, about 18 F warmer than today, even though atmospheric carbon dioxide had been decreasing for 80 million years due to coal formation in the Cretaceous. Around 55 mya, there was a sudden temperature spike that lasted for about 100,000 years. (That’s geologically sudden, i.e., 10,000 years to form.) The spike is known as the Paleocene-Eocene Thermal Maximum (PETM). Data, derived from drill cores brought up from the deep seabed in the Atlantic and Pacific Oceans, show that the surface temperature of the planet rose by as much as 15 F over the already warm temperatures. The cause is controversial.

Carbon dioxide levels rose from 1000 ppm to 1700 ppm–more than four times higher than today’s level of 385 ppm, but that rise began after the start of the temperature spike.

Isotopic analysis of carbon suggests that the culprit was methane, which is 65 times more powerful as a greenhouse gas than carbon dioxide. There are two hypothesis as to the source of methane: microbially generated methane buried in sediments along the slopes of the continental shelves; and methane clathrates. Methane clathrates are crystalline structures of methane bound to water. They form at near freezing temperatures under high pressure. They are stable up to 64 F under high enough pressure. This form of methane exists along our coasts today, frozen in the sediment at low temperatures and high pressures. They are being investigated as a source of energy.

It is speculated that volcanism and tectonic disturbance released pressure that was holding the methane in clathrates or in sediments themselves. This “sudden” release of methane caused the temperature spike. (There is nothing to prevent this from happening again.)

After that temperature spike subsided, temperatures remained warm until about 34 mya. At that point the Antarctic ice sheet began to form. Temperatures continued to drop. About 2.6 mya, continental ice formed at lower latitudes and initiated the glacial epochs and interglacial periods of our current ice age. (I will write in detail about our ice age and its cosmic connection in a future blog.)

See other chapters in this series:

Precambrian, Early Paleozoic, Late Paleozoic, Triassic, Jurassic, Cretaceous.

Throughout this series I have been using paleomap reconstructions of where continents have been. The continents are still moving. Here’s where the continents might be 50 million years from now.

References:

Shellito, Cindy, 2006, Catastrophe and Opportunity in an Ancient Hot-House Climate, Geotimes, October 2006.

In Arizona Geological Society Digest 17:

Lucchitta, Ivo, 1989 History of the Grand Canyon and of the Colorado River in Arizona.

Lynch, D.J., 1989, Neogene volcanism in Arizona.

Menges, C. M., 1989, Late Cenozoic Tectonism in Arizona and its impact on regional landscape evolution.

Scarborough, R., 1989, Cenozoic erosion and sedimentation in Arizona.

Spencer, J.E. and Reynolds, S.J., 1989, Middle Tertiary tectonics of Arizona and adjacent areas.

Spencer, J.E., and Welty, J.W., 1989, Mid-Tertiary ore deposits in Arizona.

The Cretaceous Period (145- to 65 million years ago) was hot and steamy. There was no ice at the poles. Global temperature is estimated to have been about 18 F warmer than today. Atmospheric carbon dioxide began a 145-million-year decline from about 2,000 ppm to the 380 ppm of today, in part, due to carbon sequestration by formation of coal deposits. Flowering plants appeared.

The North American continent was split by a sea connecting the Gulf of Mexico with the Arctic Ocean. Transgressions and regressions of this sea formed conditions ripe for coal formation similar to those in the Paleozoic Era. In Southern Arizona, the lower Cretaceous Bisbee Group, consisting of the basal Glance conglomerate, the Morita formation sandstones and mudstones, the distinctive Mural Limestone (which forms the cliffs just east of Bisbee), and the sandstones and mudstones of the Cintura Formation record the changes in sea level. Upper Cretaceous rocks, the Fort Crittenden Formation lie unconformably (representing erosion or structural change) upon the Bisbee Group. The lower Fort Crittenden is dominated by marginal wetland to deep-water lake deposits, whereas the upper Fort Crittenden is characterized by wetland to deltaic deposits. These rocks contain organic geochemical evidence of wildfires which suggest that seasonal aridity and wildfires were common occurrences.

There are no early Cretaceous rocks recognized in northern Arizona. Thick sequences of upper Cretaceous rocks were deposited on what is now the Colorado Plateau. These represent near-shore marine, coastal, and river-deposited sands, mudstone, and coal. Coal is mined from the Dakota sandstone at Black Mesa in Navajo County, AZ. This is overlain by the Mancos Shale, and several other sedimentary formations.

The Laramide orogeny of late Cretaceous to early Tertiary time (80- to 40 million years ago) built the Rocky Mountains and closed the inland Cretaceous sea. Subduction of oceanic crust under continental rocks along the west coast caused compression and uplift of the continent.

This was the time of emplacement of most of the porphyry copper deposits in the western U.S. Volcanism was extensive, and included the volcano that produced the rocks of the Tucson Mountains. (See the Tucson Mountain story).

 Dinosaurs roamed the land, including Arizona’s Sonorasaurus thompsoni, a new species of brachiosaurid dinosaur whose remains were first discovered in the Whetstone mountains by UofA graduate geology student Richard Thompson in 1994. Sonorasaurus is estimated to have been about 50 feet long and 27 feet tall, about one third of the size of other brachiosaurus. It may have been a juvenile or just a small dinosaur species. Sonorasaurus was an herbivore. Tooth gouges on its bones suggest it was killed and eaten by a larger dinosaur. A single blade-like tooth of a huge meat eater called Acrocanthosaurus was found near the bones and suggests that this was the predator that killed Sonorasaurus. You can see an exhibit dedicated to Sonorasaurus at the Arizona-Sonora Desert Museum.

The end of the Cretaceous Period saw another major extinction of life. Dinosaurs, pterosaurs, many marine reptiles, some marine invertebrates, some groups of mammals, and a few plant groups became extinct. The reasons are still controversial. We know that an asteroid impacted near Yucatan, Mexico and formed the Chicxulub crater about 65 million years ago. The impact is said to have vaporized rock into clouds of dust, that cooled temperatures, and created clouds of sulfurous gas, which may have killed plants with acid rain. The impact is also said to have deposited a thin clay layer containing iridium and strained quartz. However, the extinction occurred during an 800,000-year eruption of basalts that form the Deccan Traps in India. Volcanic eruptions can also product dust and sulfur dioxide emissions (and layers of iridium which characterize the K/T boundary). More precise dating shows that the Chicxulub impact occurred 300,000 years before the mass extinction. Evidence suggests that the extinctions occurred over a period of several million years.

Cretaceous Trivia:

The white cliffs of Dover, England are Cretaceous age chalk deposits.

Paul Spur, a rail stop between Bisbee and Douglas exists because Mural limestone was mined for smelter flux.

Hills carved from Cretaceous beds east of Bisbee. View is northward across Mule Gulch. The prominent white band is the upper member of the Mural limestone, forming the top of Mural Hill on the left and showing the dislocation due to the Mexican Canyon fault. Cochise County, Arizona. December 1, 1902. Plate 9-B in U.S. Geological Survey. Professional paper 21. 1904, figure 7 in U.S. Geological Survey Folio 112. 1904.

See more of geologic history:

Precambrian, Early Paleozoic, Late Paleozoic, Triassic, Jurassic

References:

Dickinson, W.R., et al., 1989, Cretaceous Strata of Southern Arizona, in Geologic Evolution of Arizona, Arizona Geological Society Digest 17.

Finkelstein, D.B, et al., 2005, Wildfires and seasonal aridity recorded in Late Cretaceous strata from south-eastern Arizona, USA, Sedimentology, Volume 52, Issue 3 , Pages587 – 599, International Association of Sedimentologists

Krantz, R.W., 1989, Laramide Structures of Arizona, in Geologic Evolution of Arizona, Arizona Geological Society Digest 17.

Nations, J.D., 1989, Cretaceous History of Northeastern and East-Central Arizona, in Geologic Evolution of Arizona, Arizona Geological Society Digest 17.

Hummingbirds are ferocious. The males jealously guard feeders and flowers. Females guard nesting sites. I’ve seen one male literally drive another into the ground and jab him with his sharp beak. They have a variety of vocalizations including a “war cry,” a buzzing to warn others away. The Rufous is particularly pugnacious.

For two years, I was involved with the hummingbird reconciliation project run by the University of Arizona. My job was to identify hummers, observe and record their behavior at the feeders in my yard. Over that time I was able to recognize individual birds of the same species, since each has a slight variation from the ideal pictured in a bird book. (And there are fertile hybrids between Anna’s and Costa’s just to make things interesting.) Hummers have good memories. They can return to a feeder year after year.

Hummingbirds live on the edge. Their small size and ability to fly forwards, backwards, upside down, and hover, requires a racing metabolism. At rest, their hearts beat 500 times per minute and this increases to over 1,200 beats per minute during flight. Their wings beat 80 times per second; body temperature is 105- to 109 degrees F.

To function, a hummingbird must consume 70% of its body weight in solid food per day (8-12 calories) and 4- to 8 times its body weight in water. They consume flower nectar (and sugar water), insects, and spiders, as well as tree sap in some areas. They can completely digest sucrose within 20 minutes. According to the Peterson Field Guide, “Despite the predominance of certain hues in hummingbird pollinated flowers, color is far less important… than the quantity and quality of the nectar. When presented with a variety of flowers, hummingbirds will maximize their energy intake by selecting for highest nectar output and richest concentration of sugars, regardless of flower shape or color. Taste also ranks above flower color…” Hummers prefer sucrose over other sugars such as glucose and fructose.

To take in the oxygen they need to burn food, hummers respire at the rate of 300 breaths per minute, even at rest. An excited hummer can breathe twice as fast. Hummers, which are the smallest warm-blooded vertebrates, have the largest heart-to-body ratio of any warm-blooded vertebrate, and the largest brain-to-body ratio of any bird.

They need that relatively big brain for their split-second aerial maneuvering. Hummers are the only birds that gain lift from both the downstroke and up stroke of their wings. The wing motion describes a horizontal figure eight. After the downstroke, the wing is turned over at the shoulder so that the up stroke becomes another downstroke.

There are over 300 species, all in the western hemisphere, and they range from the tip of South America to Alaska. There are 17 species native to the Sonoran Desert Region. Hummers in our region range in length from 2.75 inches to 5.25 inches and weigh 2 to 10 grams (0.07 to 0.35 ounces). Only one hummingbird, the ruby throat, occurs east of the Mississippi River in the U.S.

Most hummers in our region exhibit some migratory behavior. The champion is the Rufous which travels from Mexico to Alaska and back every year. Second is the Ruby Throat which migrates from the eastern U.S. to Mexico. Some travel along the coast, but others take a 13-hour, non-stop flight across the Gulf of Mexico. Those long-distance flyers try to double their body weight for fuel before the trip. Normal flight speed is 25- to 30 mph, but they can do bursts of 60 mph if necessary.

Hummingbirds are very territorial; both sexes protect feeding territories; males protect courtship territories; and females protect nesting territories. Hummers are promiscuous breeders. The male merely courts and mates with receptive females. The female may mate with several males, but she alone builds the nest, lays and incubates the eggs, and tends the young.

The nest is about two inches in diameter. The female uses plant fiber and moss bound with spider web silk. The nest may be lined with hair or feathers and decorated with leaves, bark strips, or lichens to help camouflage it. Generally, two raisin-sized eggs are laid and incubated for about two weeks. Young fledge in about three weeks after hatching.

Hummingbirds are colorful. Most of that color is not produced by pigments as in other birds, but by refraction of light by the feathers. The feathers contain filmy layers that hold granules of melanin and air bubbles, which refract light differently depending on the angle of impingement. The bubbles act as tiny prisms, breaking the light into its component colors.

Where do they go at night, especially in the winter? Hummers are often perilously close to the limits of their energy reserves. On cold nights, when the costs of keeping warm are especially high, it may be too risky for a hummer to maintain its high metabolism. In that case, it will seek shelter of a branch or crevasse, bristle its feathers to let body heat escape, and allow its body temperature to approach that of its surroundings. Its heart rate drops dramatically, and it may stop breathing for minutes at a time. It appears lifeless, clinging motionlessly to its branch with its head drawn close to its body and its bill pointing sharply upward. At daybreak it revs its metabolism and warms itself again. This temporary hibernation is called torpor. Hummingbirds become torpid not only to deal with fuel crises, but also to save energy for migration. And since birds lose moisture with every breath, becoming torpid also helps desert hummers conserve water.

Like many animals in the wild, most hummers don’t survive the first year, but those that do have a life expectancy of three to four years. Some tagged birds in Colorado are known to be 12 years old. One hummer at the Desert Museum was claimed to be 18 years old at death.

If you set up feeders, use 1 part sugar in 4 parts water in the winter, and 1 part sugar in 5 parts water in the summer. Clean the feeders before each filling. Do not use coloring, honey, or artificial sweeteners.

If you want to learn to identify hummingbirds, I recommend “Hummingbirds of North America” a Peterson Field Guide by Sheri L. Williamson. This book contains photos rather than drawings. Photos include close-ups of heads and tails which aid identification. The book also has a good discussion of natural history and good range maps. It covers 31 species. With practice, you can even learn to identify some hummers by their vocalizations. Some species (usually only the males) also have distinctive “hum” of the wing beats.

Jurassic Time, the age of dinosaurs, was from 241- to 145 million years ago. See geologic time chart. The super-continent of Pangea was breaking up and the Atlantic Ocean was born along a spreading axis.

During the Jurassic there were no Rocky Mountains. The ancestral Rockies of the Paleozoic had eroded away and the current Rocky Mountains were yet to be born. Northern Arizona, and all of what is now the Colorado Plateau was a featureless desert of blowing sand, much like the Sahara Desert today. These sands became the Wingate Sandstone, Kayenta formation, Navajo Sandstone, and Entrada Sandstone that form the arches and cliffs of parks in southern Utah such as Arches National Monument, and Zion National Park. The cartoon below shows the paleogeography.

The real action was in southern Arizona. Magmatism begun in the Triassic Period continued and moved inland, so that southern Arizona and California contained a magmatic arch and subduction zone with development of many volcanoes on the western edge of the continent. (See the hatched line in the global map, first figure above.) This subduction zone still exists along the west coast of North and South America. The figure below shows a cross-section of a subduction zone, magmatic arc, and spreading axis. To be in proper orientation for our purposes, consider that you are looking toward the south, with the Pacific Ocean on the right and the incipient Atlantic Ocean labeled “back-arc basin” in the figure.

In Jurassic time, southern Arizona was a volcanic field, and some of the volcanoes collapsed into calderas. Remnants of these calderas are recognized in the dragoon mountains near Courtland-Gleeson, in Tombstone, at the southern end of the Huachuca mountains, in the Canelo Hills, and in the Santa Rita mountains. Gold, silver, and copper is associated with the subvolcanic intrusions of these calderas. Many of the historic mining camps of southern Arizona were founded on these deposits. The Juniper Flat granite just north of Bisbee has been dated at about 180 million years and the copper deposit at Bisbee is presumed to be about the same age.**

The Jurassic was also a time of other structural complications. According to Tosdal et al. “In southeastern Arizona, movement along northwest-striking fault systems broke the area into elongate structural blocks, forming topographic highs and basins in which terrigenous clastic* and volcanic rocks accumulated.” The Canelo Hills volcanics are some of the rocks deposited at this time. Tosdal continues: ” In northwestern Sonora, southern Arizona, and southeastern California, a system of sinistral strike-slip faults, The Mojave-Sonora megashear, cut obliquely across the magmatic arc, as much as 800 km of aggregate displacement along these faults may have occurred in Jurassic time.”

At the end of Jurassic time, and extending into the following Cretaceous period, the style of tectonism changed from strike-slip shearing to normal faulting (one side down relative to the other side). This formed basins which received sediments and volcanic deposits, and eventually formed the basin which held the Cretaceous-age Bisbee Sea.

Glance Conglomerate, up to 2,000 meters thick, is the youngest Jurassic deposit in southern Arizona and forms the base of the Cretaceous Bisbee group of rocks. The Glance represents high-energy deposition of alluvial fans by debris flows and rivers along a mountain front.

For most of Jurassic time, global temperatures are estimated to have been 15 -to 20 F warmer than today, the same as in the preceding Triassic Period. Most of the land area was hot and steamy, but in southwestern North America, it was arid. Plant life consisted mainly of conifers and palm-like cycadeoids. Flowering plants had not yet evolved. On land, this was the age of dinosaurs, including flying reptiles. There were some primitive mammals, and abundant insects.

Mid-Jurassic volcanism caused atmospheric carbon dioxide to rise from about 1,500 ppm to about 2,500 ppm (vs. 390 currently) by late Jurassic time. But while carbon dioxide remained high, Jurassic time ended with an ice age. There is evidence of glaciation on some continents, but apparently temperatures did not get as cold as in the previous ice age in late Paleozoic time nor as cold as the glacial epochs of the current ice age.

Next time, the Cretaceous Period: bad news for dinosaurs.

See Chapter 4: Triassic time.

* Geologic Terms

Clastic: Of or belonging to or being a rock composed of fragments of older rocks (e.g., conglomerates or sandstone)

Sinistral strike-slip: If standing on one side of a fault, the other side would appear to move left. The San Andreas fault is a dextral (right) strike-slip fault.

Subduction: A geological process in which one edge of a crustal plate is forced sideways and downward into the mantle below another plate

Terrigenous: deposited on the earth’s crust.

**Age dating of the Juniper Flat granite yielded an age of 171 mya by potassium-argon method and an age of 182-184 mya by rubidium-strontium method.

References:

Lipman, P.W., and Hagstrum, J.T., 1992, Jurassic ash-flow sheets, calderas, and related instrusions of the Cordilleran volcanic arc in southeastern Arizona, GSA Bulletin, v.104.

Tosdal, R.M., Haxel, G.B., and Wright, J.E., 1989, Jurassic Geology of the Sonoran Desert Region, Southern Arizona, Southeastern California, and Northernmost Sonora, in Arizona Geological Society Digest 17.