Abyss of Time

As a child, the deep end of the swimming pool terrified me. At the shallow end, I could stand on the bottom with my head still safely above the surface. I swam with confidence and pleasure. The deep end, however, was a different matter. Lettering painted on the rim of the pool -- say, 9' 6" -- filled me with dread. Down by more than double my height, the pool drain possessed, I imagined, a gravitational sucking force. Were I to swim over it, surely, it would drag me under, as irresistibly as if pulled beneath by the tentacles of an octopus. A watery death awaited, my toes caught and entangled in the drain's grates. Of that, the child I was had no doubt.

The pool's deep end was for me an abyss. In its etymology, the word "abyss" derives from Greek words "a-" (without) and "byssos" (depth), thus bottomless and limitless. Usually it refers to watery, oceanic depths, but it might also suggest a crevasse, chasm, or other terrestrial void. Abyss has a connotation of terror, one coming, I suspect, from the implication that what is bottomless must also be inescapable. Moreover, it is a bottomless below, suggesting a grave, the underworld of Hades or Tartarus, and the oblivion coming with death. Few who visit there ever return to the world of the living on earth's sunny surface [1]. The related word "abysmal" has had, since the early 19th century [2], the additional connotation of a wretchedness into which one falls, for example, "the abysmal conditions of those living on the street." For the Chinese, abyss appears as an interpretation of the water over water, or Pit, hexagram of the I Ching. Other interpretations of that hexagram involve darkness, risk, and concealed danger. Fear of bottomless depths is, evidently, not strictly Western.

I am now reading Claude C. Albritton's book, The Abyss of Time (WH Freeman, 1980). A geologist, Albritton provides a history of the geological discovery of the vastness of earth's time. We might simply call such vastness "deep time". The discovery came slowly, in the successive discoveries made by geologists and others over several hundred years. Time gathered its depth (or, expanse) as these discoveries pushed out estimates of the age of the earth from 6000 years (a date derived nonscientifically by analysis of the Jewish scriptures, Genesis in particular) to today's estimate of 4.6 billion years. This increase of more than 750,000-fold has required adjustment in how we, as mortal humans, understand ourselves as existing in the matrix of time.

Albritton's title, "the abyss of time", originates in the discoveries of James Hutton, one of geology's founders. Hutton came to understand geological processes as slow and inexorable. Given sufficient time, these processes -- no different from those active at this present time -- can raise mountains and cut vast canyons. No Biblical floods or other catastrophic events are needed [3]. Instead, only time, in vast amounts, is required. Consequently, "we find no vestige of a beginning - no prospect of an end," wrote Hutton (Albritton, p. 96). Moreover, "the mind seemed to grow giddy by looking so far into the abyss of time" (Albritton, p. 103) wrote John Playfair, Hutton's collaborator and biographer.  Playfair wrote this at Siccar Point, Scotland, the site of a geological unconformity that provided Hutton with his most important insights. But why describe time with the word "abyss" considering it terrifying connotation?

In its new-found vastness, geological time seems to deny our stories of time's beginning, be it the Genesis story or the Big Bang, as well as of time's ending, say, the return of Christ or nuclear winter. Time without beginning and without end consequently loses its unfolding progressive character, becoming more nearly circular and repetitious. Sisyphus, eternally rolling his boulder up the mountain only to have it roll back down, graduates from mere metaphor and mythology. He is a man punished by the gods with futility and imprisoned in the realm of circular time. His fate and its futility are what makes understanding geological time an abyss [4]. 

Endnotes

1. Greek and Roman mythology give special attention to those few mortals who have visited and later returned from the Underworld. These special mortals include Odysseus, Aeneas, Sisyphus, and Orpheus. (Eurydice, beloved by Orpheus, almost made the list.)

2. See "abysmal" in The Oxford Dictionary of Word Histories, edited by Glynnis Chantrell, 2002.

3. This doctrine now goes by the name Uniformitarianism.

4. Albert Camus, for one, disagreed. In his essay "The Myth of Sisyphus" (ca. 1942), he presented Sisyphus as the modern absurd hero, ending his essay with the words "one must imagine Sisyphus happy". His Sisyphus defies both the gods and the circularity of time. He knows time but not the abyss. I wonder how much Camus knew about geological time.

posted: 2020-03-09, last edited: 2020-03-10 (rewritten)

How old is old?

What is the oldest thing found on earth?

Rocks, right? Some of the oldest rock formations are found in northern and eastern Canada and date back about four billion years. Immensely, unimaginably old they are, and yet the earth itself is older, dated to about 4.54 billion years. On earth, rocks are continuously recycled, broken down by weathering and erosion, and moved by water, wind, and gravity. And rocks are also built back up, reformed by sedimentation and remelting, pushed up again by our earth's ever-moving crust. Original rocks, present when our newly-created, molten planet had cooled and solidified, are likely long since recycled and remade by our dynamic living planet.

So how about meteorites, the rocky remains of "shooting star" reaching the earth's surface still intact? They are older still. At the local New Mexico Museum of Natural History and Science is found an iron-nickel meteorite collected from South America and dated to 4.55 billion years ago. "PLEASE TOUCH" says the sign by the meteor. Awed, I place my hand on its rusty metallic surface and try to feel the vastness of time that my rational mind cannot comprehend. "This may be the oldest rock you will ever touch" suggests the sign. Indeed.

Iron-nickel meteorite at the New Mexico Museum of Natural History and Science

Earth, sun, and the seven planets [1] of our solar system all originated together about 4.57 billion years ago. Originally part of rocky objects smaller than Earth but still part of the solar system, rocks that would become meteorites cooled faster and solidified sooner than Earth. Thereby they are older.

But can we go even farther back in time? Can we find even more ancient mineral-based substances on earth? Until recently I thought not. But now, I stand corrected.

Older matter ought to exist somewhere. Old as Earth and the solar system are, we are but recent arrivals. As the Big Bang creation is dated to about 13.7 billion years ago, some two-thirds of the universe's history had already passed before our solar system was created. Generations upon generations of stars and galaxies predate us and our sun. The vastness of earth's history therefore contacts to something termed "recent". Absurd! My mind rebels at this absurdity and this monstrosity. I am a trained experimental scientist. I do believe these ages. Still, I need something solid, something tangible, something to touch and feel, if only with scientific instruments, so that I can also believe in my heart and marrow as I believe in my brain. I need more evidence.

Timeline of the Universe

Late last month a scientific paper [2] appeared providing some of that evidence. The paper's title is instructive: "Lifetimes of interstellar dust from cosmic ray exposure ages of presolar silicon carbide". The words "presolar" and "interstellar" suggest matter older than the solar system and originating outside of it. "Dust" suggests solid matter, and "silicon carbide" is a particular type of mineral, one of the first minerals to form in the history of the universe [3]. Presolar grains are not new. What this paper contributes is a new method of dating them. The grains they dated are derived from the Murchison meteorite that landed in Australia in 1969. While most of the meteorite's matter dates from just after the formation of the solar system, embedded within it are trace grains of far older matter, matter containing the mineral silicon carbide (SiC). The oldest grains date to 1 to 5 billion years prior to the solar system's formation, or 5.6 to 9.6 billion years ago. As I touched the meteorite at the local museum, might my hand have come into contact with similar ancient presolar grains [4]?

Should we believe this paper? Key to answering that question is considering carefully the methods used. The authors face two challenges: (1) convincing us that the SiC grains came from outside the solar system and (2) establishing a date for their formation. For (1) the authors relied on a well-established method: demonstrating by mass spectroscopy isotopic anomalies characteristic of matter originating outside of the solar system. For (2) the authors developed a new dating method based on cosmic ray exposure. They had to. As they note in their paper, "Dating of interstellar dust directly with astronomical methods is not possible. Neither is dating based on the decay of long-lived radioactive nuclides, due to current analytical limitations and unknown initial isotopic compositions."

But can we go back even further in time?

Yes, we can go almost all of the way back, back more than 13.6 billion years, if we relax one key assumption. Up to this point, this blog post has been written from a geologist's point of view. What counts to the geologist are minerals, those underlying chemical components of terrestrial rocks, meteorites, and presolar grains. Key to the definition of mineral is the requirement that atoms continuously exist in an intact, regular, and solid structure. Recycling of rocks on earth's surface, for example, reshuffles this structure, thereby resetting a mineral's age to the most recent episode of (re)mineralization.

Chemists, in contrast, see things differently. They are more willing to let go of the requirement that dating apply to elements in their mineral form. What matters is only the elements themselves, and not their chemical neighborhood and bonding partners. All hydrogen, some helium, and traces of lithium were created in the Big Bang and predate even the first stars. Cosmologists estimate that by 379,000 years after the Big Bang, the expanding universe had cooled enough for the nuclei of the hydrogen, helium, and lithium to combine with electrons forming the first atoms.

I sip some tea, and in the water composing it, I taste and consume hydrogen dating back nearly to the Big Bang 13.7 billion years ago. Oh the places that hydrogen has been!


NOTES

1. Missing from the list of eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) is Pluto. Based on its small mass and the aberrant characteristics of its orbit (specifically, its eccentricity and large deviation from the ecliptic), Pluto was reclassified in 2006 from a "planet" to a "dwarf planet", the same status shared by Ceres, one of the larger known asteroids.

2. The article is by Philipp R. Heck et al.  and was published on 28 January 2020 in the Proceedings of the National Academy of Science, 117(4): 1884-1889. The original article is available here at no cost.

3. See Professor Robert Hazen's course, "The Origin and Evolution of Earth" (The Great Courses, 2013), especially lectures four and five. See also the Wikipedia entry on "presolar grains".

4. I am doubtful. The Murchison meteorite, a carbonaceous chondrite, has a composition distinctly different from iron-nickel meteorite displayed at the NM Museum of Natural History and Science.


ACKNOWLEDGMENT

Professor Carol Hill, her course "Planetary Geology" (now being taught at the University of New Mexico), and my fellow classmates motivated and informed this blog post.

posted: 2020-02-20, last modified: 2020-02-20

Sandia Granite and the Abyss of Time

[Listen to this post read by its author.]

Granite. Ordinary granite. Its heft weighed in my hands. I rotated the muddy chunk with numb fingers to better examine the clear quartz within. "Intrusive igneous rock", I thought. No magnifying glass was required to make out the hexagonal prisms of quartz's crystals. "Slow-cooling too", I reasoned, for otherwise the crystals would be invisibly tiny to my unaided eye.

In geology, I am a novice, a mere child for whom the slightest glint or sparkle suffices to delight. In my specimen, quartz seems to float in an amorphous matrix of feldspars -- salmon-pink colored orthoclase and white plagioclase -- with black rectangular chunks of biotite, or maybe hornblende, mixed in [1]. With a steel rock hammer, I had just chipped it out of a road cut. That road is the "Old 66", as locals call it, or "NM 333", as the highway department designates it.

Sandia Granite, formed 1.4 billion years ago, from a road cut 
on NM 333 between Albuquerque and Tijeras, NM.

Just east of Albuquerque, Old 66 traverses the geologically-rich Tijeras Canyon. Stretching, rifting, and faulting of the earth's crust in these parts 10 to 20 million years ago uplifted that slow-cooling, subterranean granite, repositioning it overhead as the Sandia Mountains, and opening this Canyon. Here history, both geological and cultural, lurks.

"Along this very road", I thought, imagining Steinbeck's Joad family escaping the Oklahoma Dust Bowl in their overloaded, westbound jalopy. "Salt of the earth, as much as this rock in my hand." Conflating the movie version with the novel, I saw in my mind's eye a young Henry Fonda at the wheel, hungry, lean, and desperate. Old 66 symbolizes America and our restless drive, whether to escape, like the Joads, or instead to celebrate. "Get your kicks on Route 66." I hear that now, in Nat King Cole's cool baritone. And here I was literally walking the very road, rock hammer in hand, collecting specimens, and, yes, getting my kicks.

Wind blew wet and cold for this bleak October day of 2019. Chilling it further was the damp wake of occasional, fast-moving traffic as we worked from the road's narrow shoulder. "Grab your specimens and go", I reminded myself. "Keep focused, keep moving, stay warm, this is only the first of several scheduled stops. Others in the group are already in the car waiting for you." For Professor Carol A. Hill's class "Geology of the Sandia Mountains and the Rio Grande Rift", this was the optional field trip for the hardcore enthusiasts.

"One point four billion years old?", I asked aloud, knowing the number from books [2], as well as from her lectures, yet not quite ready to accept it. "Yes", Professor Hill replied. It is a matter of fact. Granite. Mundane granite, quite literally mundane, removed from the earth with a whack of the hammer. This chunk in my hand is enormously, unimaginably old. That much I understood.

America, our America, in contrast, repels the cling of history, or so it seems. Everything is always changing, wrecked or improved, opinions differ, in any case superseding what came before. Nearby Interstate 40, for instance, has made Old 66 a relic of a former, forgotten era. Long gone are the Art Deco motor lodges and sleek filling stations servicing streamlined cars. And these days, who still remembers Nat King Cole? As our culture forever morphs, these rocks and this earth remain, mute witnesses to it all, biding their time.

I have long worked with unimaginable numbers. Is there anything larger than Avogadro's constant of chemistry, or anything smaller than Planck's constant of physics? Just key them into your calculator using scientific notation. Easy, right? But 1.4 billion years is more than a number. It is also history, geological history, and as history it is a human creation. I ought to be able to feel it in order to fully know it.

One way to comprehend is to temporarily put aside the units -- years -- and only consider the magnitude. America has many billionaires. Can I comprehend their wealth? (Not really. I am satisfied simply to pay off my credit card balance each month.) Instead, as we are concerned with time, what about 1.4 billion seconds? How long might that be? About 44 years, according to my 33 year old HP-15c calculator. That's human middle age. Already, I've lived more than 1.4 billion seconds. That duration I know viscerally. I feel it as aches in my joints and muscles after several hours of hiking.

The relevant quantity, however, is 1.4 billion years. Because there are about 32 million seconds in a year, the age of my granite chunk is equivalent to 32 million middle-aged human lives, stacked end to end. No, I can't comprehend that either.

Another technique is to ignore the number's size and instead locate it in the context of what is already understood. In 2003, I visited the ancient bristlecone pines high in the White Mountains bordering California and Nevada. Immediately, as I walked among these scraggly Methuselahs of trees, I comprehended -- I felt in my marrow -- their 3000 year old age. Younger than the Trojan War I reasoned [3], yet also older than Homer's singing about the War in his epics, the Odyssey and the Iliad. I could understand because the Odyssey I have known and loved since childhood. Some stories of our cultural history evidently endure unchanged.

Earth's history has analogous mileposts. Life emerged on earth between 3.8 and 3.5 billion years ago and, much later, by 0.54 billion years ago life had evolved hard shells that preserved well as fossils. Somewhere within this three billion year span between life and fossils my chunk of granite cooled and solidified from magma. But, unlike the bristlecone pines, I still have no intuition or feeling for the age of the rock in my hand. The distance between the mileposts is just too great.

I am trained as an experimental scientist. I approach geology in that way. On another field trip, to a remote location near Socorro, NM in December 2019, I found a hefty chunk of glassy, translucent crystal [4]. It formed in sheet-like layers, almost like ice. Could it also be quartz? I tried, and succeeded, at scratching it with a knife. No, it definitely was not quartz. Then I watched and listened for what a drop of hydrochloric acid would do. I neither saw nor heard fizzing, so what I had was likely not calcite either. Perhaps unwisely, I licked it. Not salty, so not halite. Using established tests and guide books, using simple instruments like a knife and acid, using my five senses, and using my fallible reasoning, I tentatively conclude that what I found was selenite (crystalline calcium sulfate).

Making 1.4 billion years troublesome to me is its unapproachable abstraction. I can't taste it or try to scratch it. I cannot relate that age to my favorite stories, whether by Steinbeck or by Homer, much less to the voice of Mr. Cole. Sandia granite is found in America but seems not to be of America. I can hold a chunk of it, but I can't fully understand it, not its age. Here, my understanding hits its limits.

Footnotes

1. Sandia "granite" is, more precisely, the granite subtype called granodiorite.

2. For the geology and rock ages, see Jayne Aubele et al., "Geology of the Sandia Mountains", chapter 5 of Field Guide to the Sandia Mountains (edited by Robert Julyan and Mary Stuever), University of New Mexico Press, 2005. For background,  Halka Chronic, Roadside Geology of New Mexico, Mountain Press Publishing Company, 1987, pp. xii-xiii, 27-31, 169-173, is helpful.

3. As I have understood it, the Trojan War was fought between 1200 and 1150 BCE. Homer, if he existed, travelled the Aegean in roughly 750 BCE and, over the course of several long nights, sang the epics to enthralled audiences.

4. This field trip is recounted in an earlier blog post, Land Beneath My Feet.

Posted: 2019-01-08. Updated: 2019-01-08.

Time and Change at Chaco Canyon

[Listen to this post read by its author.]

"A generation goes, and a generation comes, but the earth remains forever. The sun rises and the sun goes down ... There is no remembrance of former things, nor will there be any remembrance of later things yet to happen among those who come after." (Ecclesiastes, 1:4-5, 11, RSV)

Chaco Culture National Historical Park, October 2019, photos by PB Laub

Trees and their shade are mostly absent here. In their place are stark cliffs of sandstone, slowly eroding in the ceaseless, arid wind. What draws people out here, nearly an hour of slow and bumpy road from the nearest sizable town, are the remains. Stone and masonry, as well as still abundant pot shards, stand in silent testament to what once was. Eight or nine hundred years ago, Chaco Canyon was a settlement or destination for the Ancestral Puebloan people, a site perhaps of trade or of worship. Then, abruptly, people disappeared; the site was abandoned.

What happened and why has been the subject of continuing speculation and debate. Some, like Jared Diamond, in his 2005 book Collapse, look for ecological or social causes of decline. Might the clear cutting the timber nearby been a factor, or over-reliance on food imported from great distances? Others, like Anna Sofaer, find, amidst the apparent disaster, evidence of advanced astronomical knowledge employed by the Puebloan people. So, might Chaco be a warning that feats of science and engineering offer little protection from societal collapse? The Roman Empire is long gone too, though their marvels of engineering, the aqueducts and the Coliseum, still stand.

I visited Chaco Culture National Historical Park last month, coming up from Albuquerque with others for a long day of hiking. I could write about a long climb up a narrow slot canyon beside Kin Kletso, about how glad I was not to know in advance about the steep ascent and, worse, the steep descent awaiting me. But no. More memorable was the enigmatic feel of the place, first experienced as an absence and, later, as a presence.

Fossils found in sandstone at Chaco Canyon, October 2019, photos by PB Laub

Fossils abound in the hard sandstone underfoot. You need not seek them out. Fossil impressions of shells and ripples suggest an ancient sea, one dated to the Cretaceous Period 85 to 75 million years ago. Then, a vast interior sea -- called the Western Interior Seaway  -- bisected the still-forming North American continent into distinct land masses. Once water washed this parched land. Walk further and notice what looks to be rusting rebar poking up through the rocks. "What the hell?", I wondered, baffled. What they are, a park ranger later told me, are three-dimensions casts of burrows made by crustaceans. Ophiomorpha Nodosa these casts are called. Iron in the cement filling the casts rusts, just as rebar rusts. And, being harder and more erosion-resistant than surrounding rock, these rebar-like casts are revealed as the softer surrounding rock disintegrates back into sand.
Even the hardest of rocks weather and erode. Sandstone crumbles back into the sand from which it was made, at some later time to be melted, compressed, or cemented into new rock. In geology, this is taught as the Rock Cycle. The cycle shows how rocks are forever being recycled and remade, the past they reveal erased and consumed.

Chaco is a somber place, a mute monument to the relentlessness of time. Seeing similar remains near Los Alamos several years ago, I wondered aloud, "and what happened to the people who lived here?" Someone overheard and surprised me, saying, "Oh, they're all around you. Their descendants are the people of New Mexico's pueblos." Evidently, continuity remains even as the connecting strands vanish.

Since that small epiphany, I've wondered how the world would feel if we let go and stopped resisting the passage of time. Ecclesiastes, the book of the Jewish canon quoted above, urges a return to God as answer to the ravages of time. Maybe, or maybe not. Rather than lamenting the brevity of life and the fragility of memory -- "there is no remembrance of former things", Ecclesiastes insists -- we might instead ride the wave of time as long as we live, celebrating the dynamic earth and its cycles, looking to the sky not for Heaven but for the heavens of stars and planets moving in a mathematical precision that we and our Native American brethren have figured out.

posted: 2019-11-23, last edited: 2019-11-24