Mammoths

Will return to Santa Cruz between 1714 and 1732 in a few weeks. Now, back to life in early Spain.

The Miocene, which began 23 million years ago, was the last truly warm period before the onset of the great glaciers. The mastodon family split from the emerging elephant one in Africa some 22 million years ago. By 11 million years ago, the Mammut genus had crossed to North America. Mammoths separated from Asian and African elephants around 6 million years ago, just before the era ended 5.3 million years ago.

As northern temperatures cooled during the Pliocene, grass lands that had developed in the Miocene spread. The first of the mammoths migrated into Europe about 3 million years ago. It became the Mammuthus meridionalis found in the cave paintings of Spain and France north of the Pyrenees.

The European Mammoth was already in North America when the late Pleistocene developed 1.8 million years ago. The species evolved into the steppe mammoth of central Europe (Trogontherii) and the Columbian mammoth (Columbi) that ranged from the northern United States into central America. Woolly mammoths (Primigenius) came later, when the cold became more intense in the north.

Based on the habits of modern elephants and the sizes of mammoth skeletons, zoologists believe Columbian mammoths would have needed about 500 pounds of food a day and up to 40 gallons of water. They also would have dropped about 400 pounds of dung.

If the grass were anything like modern timothy, there could have been as much as 4,000 pounds of hay on an acre. That could have supported eight mammoths for one day, or a larger herd for part of a day. Every day, as they mowed grass tops they left fertilizer and conditioned seeds.

Mammoths didn’t begin as grass eaters. In the early years of the Pleistocene, 1.5 to 2.5 million years ago, the European mammoth browsed woodlands of oak, ash, beech, hemlock and wing nut hickory. Their molars had comparatively low crowns with 12 to 14 ridges to chew leaves, bark and fruit.

During glacial advances, which trapped water, the climate dried. Winds blew sand against mountains, and loosened more grains that spread into great dune fields near the mountains. When conditions warmed, water collected. The Danube waterway that ultimately flowed across the northwestern lowlands toward England began developing around 900,000 years ago.

Local mammoths adapted to the steppe tundra marked by the light pink band bordering the gray glaciers on the map Their molars had higher crowns with 18 to 20 ridges to withstand the grit embedded in the coarse grasses. It’s droppings no doubt added to the growing fertility of the Ukraine and adjacent Danubian plains.

The Great Plains east of the Rockies was temperate steppe grassland (peacock blue on the map). Columbian mammoths had a few more ridges, perhaps 20 to 22. A male mammoth found in southeastern Utah’s Manti La-Sal National Forest had remains of sedge, grass, fir twigs and needles, oak, and maple in his stomach. The dung left in Bechan Cave, also in southeastern Utah, was 95% grass and sedge, with sedge composing about a third of the fossils. The rest were birch, rose, saltbush, blue spruce, wolf berry, and red osier dogwood.

It was colder in the polar and alpine desert where woolly mammoths adapted with heavier coats and 26 ridges on their molars. Last year, Eske Willerslev’s team published an analysis of 50,000 years of vegetation preserved in permafrost. It showed the environment was dominated by flowering plants like northern plantain, which thrive when their seeds are trampled. It was only when grass and shrubs replaced the forbs around 12,000 years ago that woolly mammoths disappeared.

The last known Columbian mammoth died 12,850 years ago. The American mastadon, Mammut americanum, survived a little longer in the plum colored taiga in the eastern part of North America until 10,500 years ago.

Notes: Pliocene temperatures were cooler than Miocene, but warmer than today. Some palaeontologists believe Trogontherii is the species that crossed into North America to evolve into the Columbian. The nomenclature and relationships between species have been refined several times. Most scientists would agree they could change again when more bones are found and more scientific tests are run.

Haynes, Gary. Mammoths, Mastodonts, and Elephants, 1993.

Lister, Adrian and Paul Bahn. Mammoths, 2007 revised edition; includes data on molar evolution.

Muitoni, Giovanni, Dennis V. Kent, Giancarlo Scardia, and Edoardo Monesi. "Migration of Hominins with Megaherbivores into Europe via the Danube-Po Gateway in the Late Matuyama Climate Revolution," Rivista Italiana di Paleontologia e Stratigrafia 120:351-365:2014.

Peters, Amy. "How Many Bales of Grass Hay per Acre from the Average Pasture?," Oregon State University Extension Service website. Any estimate of pounds per acre makes assumptions about species, moisture, and soil fertility. This is a generic number. If you lower the yield, you simply decrease the size of the herd.

University of California, Berkley. "About Mammoths," university website.

Willerslev, Eske, et alia. "Fifty Thousand Years of Arctic Vegetation and Megafaunal Diet," Nature, 6 February 2014. The northern plantain is Plantago canescens.

Graphics: "Last Glacial Maximum Vegetation Reconstructed vegetation cover at the Last Glacial Maximum period ~18,000 years ago-( ~16th millennium BC), describing the type of vegetation cover present, based on fossil pollen samples recovered from lake and bog Sediments." Based on J. M. Adams, Global Land Environments since the Last Interglacial, 1997, and on N. Ray and J. M. Adams. "A GIS-based Vegetation Map of the World at the Last Glacial Maximum (25,000-15,000 BP)," Internet Archaeology 11, 2001. Uploaded to Wikimedia Commons, 16 December 2006 by Fabartus, revised 26 November 2007 by J. Rockley.

Ice Age Española

The great glaciers of the Pleistocene were more real in Michigan where I grew up than they are in the Española valley. As a child I imagined a great blanket of snow called Illinois sidling over my neighborhood, then retreating, only to reappear in a few thousand years as the Wisconsin glacier.

Archaeologists today don’t mention glacial episodes for sites that weren’t under ice. They prefer to use the marine isotope stages developed by Cesare Emiliani and Nicholas Shackleton. The MIS numbers demarcate variations in ice composition that occurred when expanding glaciers monopolized the lighter oxygen isotopes in water, leaving the heavier ones in sea beds. Even MIS numbers are cold periods, odd numbers warm.

[Click on table to enlarge]

The stages have the advantage of avoiding labels specific to Europe and North America and help define relationships between the different ice sheets. In New Mexico, the Bull Lake glacier occurred during the Illinois in the northeast and the Riss in Europe. The ice was centered in northwestern Montana and reached down to the San Juan mountains in southern Colorado.

The later Pinedale coincided with the Wisconsin and the European Würm. It’s icecap rested on the Yellowstone Plateau, but it left glacial lakes in the Sangre de Cristo: Katherine and Nambé near Santa Fé Baldy, Horseshoe in the headwaters of the Red River.

Scott Renbarger believed the trees blown down near Trailrider Wall were growing in a moraine. Ponderosa pine roots reach deep when there’s no surface water, but only go 3' down in water-retentive soils. Rocks can trap water to create undemanding environments.

Abandoning the names of glaciers obscures the fact their affects were felt far away. When glaciers were expanding they absorbed water that otherwise would have fallen as rain. Areas beyond the ice fields dried. Winds blew their dust against mountains, grinding rock surfaces into particles that fell into great dune fields. The Great Plains and the rich farm lands of the Danube River valley began as Pleistocene aeolian deposits.

Stephen Hall said the dominant species in San Juan County and the Chuska Mountains during cold spells were piñon and Ponderosa pine. Limber pine also grew in San Juan County. Sagebrush grew in the warmer periods called interglacials. In those millennia, water was released, lakes formed, and rivers were swollen by rain.

In the Española valley the released waters sometimes brought down boulders that temporarily blocked White Rock Canyon. Then floods formed wetlands that filled existing lowlands and left a deceptively level surface. When the waters receded, they left behind badlands that border the eastern valley.

The badlands east of Llano Road between the high school and the Santa Cruz cemetery are fingers of fine-grained sand, siltstone and sandstone. Daniel Koning suspected they "may possibly lie near the north edge of a former playa or lake."

Farther north, east of San Juan Pueblo, rocks from the Middle to Upper Pleistocene have been judged 50,000 to 300,000 years old. About 25 to 40% of the pebbles are cobble sized. A bit south toward the casino, there are fewer cobbles, 10 to 30%. The "light yellowish brown to very pale brown pebbly sand" contains some quartzite. Sitting atop the eastern badlands, wind driven sand remains.

Notes: Quotations are from one of the two Koning reports below. They can be downloaded from the New Mexico Bureau of Geology and Mineral Resources website under the tabs for Publications/Maps/Geologic Maps. Locations are from the maps.

Hall, Stephen A. "Ice Age Vegetation and Flora of New Mexico," in S. G. Lucas, G. S. Morgan, and K. E. Zeigler, New Mexico’s Ice Ages, 2005.

Koning, Daniel J. Preliminary Geologic Map of the Española Quadrangle, Rio Arriba and Santa Fe Counties, New Mexico, 2002, map and report.

_____ and Kim Manley. Geologic Map of the San Juan Pueblo Quadrangle, Rio Arriba and Santa Fe Counties, New Mexico, 2003, map and report.

Oliver, William W. and Russell A. Ryker. "Pinus ponderosa Dougl. Ex Laws," in Russell M. Burns and Barbara H. Honkala, Silvics of North America, Volume 1, 1990.

Renbarger, Scott. "A Glacial Moraine in the Rio en Medio Watershed," Geological Joy in New Mexico, 23 July 2013. If you want to learn more about glaciers in the Sangre, he includes some wonderful pictures with his blog post.

Photographs:
1. Sagebrush, Taos Plateau with gorge in distance, 11 December 2011.

2. Badlands east of Llano Road between Santa Cruz cemetery and Española high school, 22
April 2015.

3. Badlands east of San Juan pueblo, seen from route 68 looking east, 20 May 2015.

Pliocene Grasses

The Pliocene followed the Miocene about 5.3 million years ago. Continuing tectonic movements finally affected weather patterns. The collision of the Eurasian and Indo-Australian plates and subsequent uplift of the Himalayas modified air currents from Arabia to the Pacific.

The new Indian and Asian monsoons created unique fire regimes. Grasses grew rapidly during very wet seasons, then dried and burned at the end of dry seasons to release carbon dioxide into the atmosphere. Lightening fires occurred several times a decade.

The Caribbean plate shifted a little west to connect North and South America. Water no longer flowed between the Pacific and the Atlantic. The second got less rainfall and grew saltier than the first.

The continued rise of the Rockies may have modified the jet stream’s path. The conjunction of Eurasia and Africa created a temporary rise in the salinity of water in the Mediterranean area.

Changes in oceans delimited Pliocene boundaries. The Zanclean Flood into the Mediterranean marked the beginning. The replacement of the calcareous nanoplankton Triquetrorhabdulus rugosus by another calcareous plankton, Ceratolithus armatus, defined the close.

All trees, flowering plants, and grasses use photosynthesis to convert atmospheric carbon dioxide and soil water into food. Most use a biochemical process called the C₃ pathway. About 7 million years ago, grasses utilizing a different method, the C₄ pathway, began displacing woodlands and C₃ grasslands. The new grasses in Asia could regrow rapidly after fires.

The C₄ pathway first evolved much earlier, maybe 30 million years ago, possibly in response to decreasing levels of carbon dioxide levels during the Oligocene that preceded the Miocene. It was reinvented by at least 45 plant lineages, probably in response to other needs.

On the North American plains it’s favored today by drought resistant grasses. In my yard, black grama and ring muhly are C₄ plants, needle grass and June grass are C₃. The first two are warm weather plants that bloom during the late summer monsoons; the others are cool weather ones that are blooming now.

In southwestern Africa, Sebastian Hoetzel’s team found C₄ grasses spread "alongside increasing aridity and enhanced fire activity." Their off-shore drilling rig found grass pollens blown from the Kalahari were 30% of the total 8.4 million years ago. They had increased to 70% by 6.8 million years ago. Plant waxes indicated the C₄ grasses were initially insignificant, but became dominant about 6 million years ago. At the same time, the amount of charred particles in the deep sea sediments increased between 7.1 and 5.8 million years ago.

In the Awash Valley of northeastern Africa, Thure Cerling’s group discovered savannas replaced woodlands about 6 million years ago. They existed in the years when the Homo genus was diverging. Savannas, by definition, are no more than 40% trees, woodlands no more than 80%. Forests have even more trees.

The transition to C₄ vegetation did not occur in the eastern Mediterranean, according to Erika Edward’s team, even though it was at the same latitude as the North American plains and China where the change did occur. Robert Thomas and Margaret Orr noted temperate grasslands lacked the trees found on savannas and had greater rainfall than steppes.

The two grasslands supported different animal communities. Today, rhinoceroses, wild horses, lions, wolves, jack rabbits, deer, and foxes are associated with prairies, while steppes have badgers. Savannas, on the other hand, support modern day antelope, buffalo, lions, leopards, hyenas, and elephants.

In the Sand Hill prairies of Nebraska, Timothy Heidorn and Anthony Joern found modern grasshoppers preferred C₃, if given a choice, but ate whichever was available. The biologists thought the reason was C₄ leaves were less nutritious. The thick cells walls characteristic of its pathway made it difficult for insects to access and digest the leaves’ protein and carbohydrates.

Notes:
Cerling, Thure E., et alia. "Woody Cover and Hominin Environments in the past 6? Million Years," Nature 476:51-56:2011.

Heidorn, Timothy and Anthony Joern, "Differential Herbivory of C3 versus C4 Grasses by the Grasshopper Ageneotettix deorum (Orthoptera: Acrididae)," Oecologia 65:19-25:1984.

Edwards, Erika J., Colin P. Osborne, Caroline A. E. Strömberg, Stephen A. Smith, and C₄ Grasses Consortium. "The Origins of C4 Grasslands: Integrating Evolutionary and Ecosystem Science," Science 328:587-591:2010.

Hoetzel, Sebastian, Lydie Dupont, Enno Schefuß, Florian Rommerskirchen, and GeroldWefer. "The Role of Fire in Miocene to Pliocene C₄ Grassland and Ecosystem Evolution," Nature Geoscience 6:1027_1030:2013. They used the equipment of the Ocean Drilling Program, which
is sponsored by National Science Foundation and the Joint Oceanographic Institutions. The latter is chaired by James D. Watkins, retired US Navy admiral.

Keeley, Jon E. and Philip W. Rundel. "Fire and the Miocene Expansion of C₄ Grasslands," Ecology Letters 8:683-690:2005.

Thomas, Robert and Margaret Orr. "Savanna", 1999, and "Colorado Prairie," 2001, in Charles Webber, California Grassland, 2002, reproduced on the University of California at Berkley’s Museum of Paleontology’s website at "The Grassland Biome."

University of Utah. "Six Million Years of Savanna: Grasslands, Wooded Grasslands Accompanied Human Evolution," ScienceDaily, 3 August 2011.

Photographs:
1. Needle grass, Stipa comata.

2. Ring muhly, Muhlenbegia torreyi. Each year the new growth is along the outer edge of the previous growth. The resulting rings capture water that nurses seeds of other plants.

3. Black grama, Bouteloua eriopoda. It also grows in rings, but the center usually remains alive.

4. June grass, Koeleria cristata. It tends to sprout when it’s wet in the spring, then die in the heat of summer when it doesn’t get the water it needs.

Miocene Española

Our major landmarks appeared in the Miocene that lasted from 23 to 5.3 million years ago. It’s hard to visualize a time when the land was relatively level with the surrounding Santa Fé, Pajarito, Colorado, and Taos plateaus. The surface would no longer have been the smooth water bed left by the retreating Western Inland Sea.

In the preceding Eocene that began 56 million years ago, the smooth edge of the Farallon plate had bumped into the buried remains the Yavapai-Mazatzal boundary. When the Picurís-Pecos fault intersected the Embudo fault, faults multiplied. The central Sangre de Cristo from Santa Fé north to Picurís began sinking while the two ends, Taos and Albuquerque, rose.

Shari Kelley and Ian Duncan have found evidence the Sandías and Truchas range were lifting again 35 million years ago, in the early Oligocene. The Picurís range recovered, and began rising a million years later.

A chunk of rock near Peñasco collapsed between the Pilar-Vadito fault on the northwest and the Santa Barbara on the southeast. The Jicarilla fault ran around the east end. The oldest surface rocks we have in this area are siltstone, sandstone, mudstone and claystone washed down from Peñasco.

These gravels cover Los Barrancos, a furrowed ridge skirted on its east by the road to Santa Fé. It’s laced with north-south fault lines starting above the modern Pojoaque river, crossing highway 84, and continuing across the Santa Cruz river. They’ve been roughly dated to the middle Miocene, 14.5 to 5 million years ago.

Coarser rocks from the Peñasco Embayment formed the bad lands on the east side of the valley north of the Santa Cruz. Perhaps they were the wash from that unnamed river, perhaps its course changed. Cobbles also spread over an old dune field in the north that had begun retreating between 11.5 and 9 million years ago.

The rock underlying the Española Basin dropped along the Pajarito fault. The half graben stayed connected on the east, tilting the block to the west and north. When it fell, the effects reverberated along the Embudo fault that runs northeast from the northern end of the valley.

Then the volcanos began. In the Arroyo Seco valley east of Los Barrancos, Ted Galusha and John Blick counted 37 layers of ash in the surrounding rocks. Tchicoma was formed between 7 and 3 million years ago.

Volcanism continued into the Pliocene era that began 5.333 million years ago. The southern Black Mesa formed about 4.4 million years ago, but the magma cooled in its neck, stopping the flow and sending it elsewhere in the Jémez. During the Ice Age, the surrounding cover disappeared, leaving the stem and a slope of debris to one side.

Rifting moved north and east. The Taos Plateau volcanic field became active about 4.5 million years ago. It threw lava that landed on that old dune field, capping the northern Black Mesa between 3.8 and 3.3 million years ago.

While the volcanos were spewing ash in the west, life continued on the other side of the basin. Grasses had multiplied in the Miocene and so did the animals that fed on them. The now extinct forms of camels, horses and rhinoceroses replaced the dinosaurs that had been lost at the end of Cretaceous mentioned in the last post.

In the Arroyo Seco basin, Galusha and Blick said the ash was never too thick to kill grazing mammals. They simply left when rains stimulated by eruptions flooded their feeding grounds. No bones are found in the ash layers or in the ones immediately above. They came back when the grasses recovered.

Notes:
Galusha, Ted and John C. Blick. Stratigraphy of the Santa Fe Group, New Mexico, 1971.

Kelley, Shari A. and Ian J. Duncan. "Late Cretaceous to Middle Tertiary Tectonic History of the Northern Rio Grande Rift, New Mexico." Journal of Geophysical Research Vol. 91:6246-6262:1986

_____ and Rachel L. Landman. "Low-temperature Thermochronologic Constraints on the Tertiary Cooling and Unroofing History of the Southern Sangre De Cristo Range, New Mexico," Geological Society of American, annual meeting, 2013.

Koning, Daniel J. Preliminary Geologic Map of the Española Quadrangle, Rio Arriba and Santa Fe Counties, New Mexico, 2002, map and report.

_____ and Kim Manley. Geologic Map of the San Juan Pueblo Quadrangle, Rio Arriba and Santa Fe Counties, New Mexico, 2003, map and report.

_____, William C. McIntosh, and Nelia Dunbar. "Geology of Southern Black Mesa, Espanola Basin, New Mexico; New Stratigraphic Age Control and Interpretations of the Southern Embudo Fault System of the Rio Grande Rift," New Mexico Geological Society, Guidebook, 2001.

McDonald, David W. and Kent C. Nielsen. "Structural and Stratigraphic Development of the Miranda Graben Constrains the Uplift of the Picuris Mountains," New Mexico Geological Society, Guidebook, 2004.

Riecker, Robert E., Peter W. Lipman and Harald H. Mehnert. "The Taos Plateau Volcanic Field, Northern Rio Grande Rift, New Mexico," in Riecker, Rio Grande Rift: Tectonics and Magmatism, 2013.

Photographs:
1. Exposed tilted rocks, road from Dixon east toward Peñasco, 8 October 2011.

2. Los Barrancos near Black Mesa Golf Course, 15 January 2012.

3. Two of the Three Sisters knobs in the Arroyo Seco valley, 2 November 2011.

4. Northern Black Mesa west of Chamita, 17 February 2013; note the different sizes of the rocks by layer.

5. Arroyo Seco valley looking east from highway, near where they built the overpass, 2 November 2011.

Mesozoic Española

Geologists today read the earth’s biography as a finite set of patterns grounded in the laws of thermodynamics that recurred in different environments. After Mazatzal, more volcanic fields formed and joined the continental mass, cementing us in. We moved with the Laurentian mass, sometimes joined with other continental masses, sometimes alone. At times we were in temperate latitudes, and at others on the north pole.

In the Triassic phase of the Mesozoic era we were part on the supercontinent Pangea sitting on the equator. The sun beat down most days of the year. Much of the land was arid, too far from the surrounding ocean to get any rain. The mass was so large, heat rising from the center was trapped by a crust that never cooled.

Accumulated heat began melting the underside of the crust. It forged an opening that divided Pangea into Laurasia on the north and Gondwana on the south. Water flowed through. The first rocks found in this country that mark this movement are the Stockton Formation from 237 to 207 million years ago. They’re part of a larger group of basins found from Nova Scotia to Georgia.

Dinosaurs roamed the Abiquiu area some 205 million years ago.

Rifting tends to be followed by volcanic activity along the rupture. Around 185 million years ago, still in the Jurassic age, a line of volcanos formed under the Atlantic ocean. When they erupted, sea levels rose, and Laurasia was pushed away.

About 125 million years ago, the outer edge of Laurasia was located somewhere in Utah when it began slipping over the heavier Falleron plate. Ocean crust is made of basalt, continental of granite. The contact began forcing up deeply buried rocks.

Meantime, sea waters had risen enough to flow down from what is now Hudson’s Bay. They flooded the area between the Laramide mountains on the west and the Appalachians on the east. Sarah Machin and her colleagues have found zircons in the Albuquerque area that indicate the waters were there by 99.4 million years ago.

All that preceded it was washed away by the great Western Inland Sea of the Cretaceous period. However, dinosaurs left their tracks along the western shore near modern Clayton.

The eastern edge of the Farallon plate reached western New Mexico about 80 million years ago,
when the central Rockies began rising. It was about the time North America finally broke away from Europe.

Farallon continued creeping under the continental crest until it began pushing up the western Santa Fé range of the southern Sangre de Cristo about 74 million years ago.

Sometime around 66 million years ago, the planet collided with a massive comet or asteroid that left a layer of iridium in the clay. The dust blocked the sun, killing off species of plants that depended on photosynthesis. Some 57% of those in North America disappeared.

The loss of forage, in turn, decimated animal populations, including the dinosaurs. The mammals that survived lived on insects and worms. Water plants and animals, along with fungus, were less affected.

Exactly where, why, and how the mass extinction occurred is still being debated by scientists, but the fact it happened is accepted. It’s recorded in clay and fossils.

Notes:
Landman, Rachel L. and Shari A. Kelley. "Low-temperature Thermochronologic Constraints on the Tertiary Cooling and Unroofing History of the Southern Sangre De Cristo Range, New Mexico," Geological Society of American, annual meeting, 2013.

Machin, Sarah, Jeffrey Amato and Spencer Lucas. "The Age of the Encinal Canyon Member of the Dakota Formation: New Insights into the Early-late Cretaceous Transgression of the Western Interior Seaway into North-central New Mexico," New Mexico Geological Society, annual meeting, 2013.

Graphics:
1. Pangaea as visualized by Kieff, uploaded to Wikimedia Commons, 20 October 2009.

2-3. Breakup of Pangaea as visualized by US Geological Survey; "Historical Perspective," last updated 7 August 2012 by J. M. Watson.

4. Diagram showing the dark blue oceanic crust of the Farallon plate sliding under the tan continental crust of the North American plate to force up the Rocky Mountains; uploaded to Wikimedia Commons by Melanie Moreno, May 2006.