Today’s post discusses some of the rocks exposed in the valleys, gorges, and road cuts that dissect the Harz Mountains (Fig. 2).
We approached the Harz uplands from the east (site A in Fig. 2), where we encountered mines based on removing sedimentary rocks for use as building material (Fig. 3).
The mines in Fig. 3 were removing desired beds from the Tanner Graywacke ( age ~360-320 Ma), a poorly mixed sedimentary rock (e.g. graywacke) originally deposited in ocean trenches associated with volcanic island arcs. The Tanner graywacke ranges from mudstone to conglomerate. It forms medium beds with variable texture, and has been tilted to varying degrees (Fig. 4).
Our route east of the Harz Mountains (red line in the inset of Fig. 2) took us to site B, where we encountered more facies of the Tanner Graywacke (Fig. 5).
Our path (red line in Fig. 2 inset) led us into a valley between the small highlands where Figs. 4 and 5 were taken. This valley is filled with a lake, and probably follows a fault zone between Site B and the main Harz Mountains to the north (Fig. 6).
Our journey followed the southern margin of the Harz Mountains (red line in Fig. 2 inset), taking us by Site C, where we found nearly horizontal beds of Tanner Graywacke exposed along road cuts. We couldn’t stop until we found a rest area, where a large block was available for close examination (Fig. 7).
We continued around the western end of the Harz Mountains and found exposures of the marine deposits (including evaporites and carbonates) that underlay the town of Kelbra (Fig. 6), including a thick sequence of either salt or anhydrite (Fig. 8).
This post reveals rocks that are widely separated in time while being found near each other, supporting the Harz uplift as they do (Fig. 2). As the title of this post suggests, geology is not a series of isolated events. Let’s get the rest of the story.
The Tanner Graywacke was deposited in an island arc, a tectonic region in which oceanic crust is being subducted beneath either a continental (or less often an oceanic) tectonic plate, about 350 million years ago. What was happening on the opposite shore of this proto-Atlantic ocean (aka Iapetus)?
I have encountered rocks of similar age in northern Virginia and discussed them in previous posts. On the west side of Iapetus, during a mountain-building event called (in America) the Acadian Orogeny, a series of island arcs were being subducted/accreted to form a series of suspect terranes. This orogeny was only a phase of the collision of Laurentia (porto-north America) and Avalon (proto-Europe), which endured for most of the Paleozoic era.
The next problem is what happened during the ensuing 100 million years, between deposition of the Tanner Graywacke and the evaporites and carbonates we encountered west of the Harz uplands (Fig. 8)? The collision was completed and Pangaea had been born of two continents…
The mountains rose and they were eroded almost as quickly by wind, rain, and ice, creating massive layers of sediment to the east (modern Europe) and the west (e.g. the Catskill Delta in New York). By 230 million-years ago, the earth’s upper mantle changed its mind and tore the newly formed supercontinent apart, creating rift valleys like that of East Africa in what is now Virginia. Splitting a continent can take as long as building one, but this was a relatively rapid event in geological time; by 200 million-years ago, diabase dikes were injected into the sedimentary and metamorphic rocks created by the closing of the porto-Atlantic Ocean (Iapetus) and the split was well under way. Alluvial and fluvial sediments were collecting in isolated basins in what is now Virginia, and evaporites were settling to the bottom of lakes and brackish coastal waters in Europe, as the ocean invaded…
Jump ahead 200 million years…
I love it when I can understand what the rocks are telling me…
I reported on the geology of this area in a previous post, but I didn’t have much time to explore the area on that outing, so this trip I followed trails all the way around the park. This was the site of a battle early in the American Civil War, October, 1861. The cannon (Fig. 1) is a metaphor of how geology is always in front of us; it isn’t just about really old rocks, but also rivers and beaches, even gas and lava being belched out by volcanoes. That’s all geology too. For example, this battle took place in a field (Fig. 2) .
There isn’t much arable land along the Potomac River here because of the rocky soil, but there are a few pockets of land suitable for farming–flood plains left as reminders of the ancient river’s meandering, while it cut its way through rock, gravel, and mud to reach its current position (Fig. 3).
The bottoms of the gullies were paved with tilted layers of sandstone and siltstone (Fig. 4), sediment originally deposited in intermontane basins like those that occur in western North America (Fig. 5).
I’d like to finish this post with a thought experiment: Imagine the sediments being carried away from the camera in Fig. 5, passing into the distance to collect in the wide valley that fronts the major fault-block mountain range, seen in the distance; now, imagine everything you see in Fig. 5 being worn down by water and wind and ice, until the sand and silt filling the lowlands in front of the camera is buried beneath the erosional product of Piestewa Peak; imagine that pile of sand and silt and clay being buried many miles beneath the surface, for millions of years.
Can you imagine the rocks seen in Fig. 4?
I’ve been talking about mountain building events that continue for hundreds of millions of years a lot in my posts, referring to the erosion of mountains into mud, silt, and sand, carried by rivers to be deposited as broad expanses of sediment. On sufficiently long time scales, this is an accurate representation of the delicate balance between uplifting mountains and the inexorable influence of rain, ice, wind, and water to eradicate all evidence of an orogeny. For example, the collision of North America with Europe and Africa required nearly all of the Paleozoic Era, beginning with the Taconic Orogeny (550-440 Ma), reaching a crescendo during the Acadian Orogeny (375-325 Ma), and culminating in the Alleghanian Orogeny (325-260 Ma). By the way, the abbreviation Ma (mega annum) is used to indicate dates that were determined by radioactive dating, rather than the more ambiguous “my” for millions of years. There is uncertainty (error bars can never be zero), but not with respect to the general timing of geologic events.
This post is going to examine details of how uplifted rocks can be broken down into pieces that are weathered while being transported to their final resting place, whether in a river, lake, shallow bay, or the deep ocean.
Vermont (Fig. 2) was entirely covered by ice several times during the last couple million years.
The rocks at Smuggler’s Notch are the same ones we saw in the Taconic Mountains and along the White River. They are equivalent to those we encountered along the Potomac River, 500 miles to the south. What happened when rocks formed as much as 20 miles beneath the surface are exposed to low pressure and temperature?
There is a lot of missing rock from the cliff shown in Fig. 3. Where did it go?
How did these huge blocks get where we find them today?
Mechanical weathering doesn’t stop when the fallen block comes to rest. Then, water carries small grains and uses them as abrasives to grind the once-humongous blocks into gravel (Fig. 6).
All that bumping and grinding eventually produces a scene like that seen along the path of the White River (Fig. 7), with bedrock resisting the seasonal onslaught of gravel and sand carried by intermittent, torrential flows.
I hope this post connects the dots between the loftiest peaks (Fig. 1) and the lowest streams (Fig. 7).
The second day of our field excursion covered quite a bit of the geological history of Tasmania, so we’re going to continue discussing this very long day (from Cradle Mountain to Hobart) in this post. To summarize, we saw exposures of Proterozoic (1600-540 MY) and Cambrian (509-485 MY) sedimentary and volcanic rocks between the coast and Cradle Mountain (see Fig. 1 for final location). These were metamorphosed and indicative of hydrothermal activity in the region, as discussed in a previous post.
The last post discussed remineralization and granitic intrusion into these rocks, especially Paleozoic rocks, culminating in the extensive mining activity centered on Queenstown, the “top of the world” so to speak, because these are some of the highest elevations in Tasmania.
Today’s post is going to take us from Queenstown to Tasmania’s official continental divide. Most of the included photos were taken about 30 miles east of Queenstown, where the pin in Fig. 1 is located. We will be examining rocks primarily from the Tyennan Group, but not as strongly deformed and metamorphosed. We are moving east of the Paleozoic trough where most ore bodies were emplaced. The sediments consist of fine-grained (pelitic) schist and quartzite (sand-sized particles), and some conglomerate deposited between 1600 and 541 MY ago.
The road cuts exposed rocks that are tilted but relatively undeformed (Fig. 2), such as this sequence of fine-grained sediments, with thin sandstone layers interbedded.
Examined up close, the sandy layers have lost their original bedding but have not developed the strong visible layering (foliation) commonly associated with what are called schists (Fig. 3).
These sediments varied substantially, as seen in Fig. 4, which shows more sandy layers and a reduced volume of fine-grained sediments.
The area in Fig. 1 contains many faults associated with volcanism and intrusion during the late Proterozoic and early Paleozoic (~1600-500 MY). In some places the rock layers of this area are vertical (Fig. 5).
Figure 5B has been annotated to better show some features of deformation without strong remineralization. The irregular lines showing deformed bedding are more-or-less original variations in particle size and/composition (i.e., sedimentary layering) that has been squeezed and had the grain size of crystals increase in response to heat and pressure. The joint pattern has nothing to do with this but came later, as the rocks cracked from cooling and reduced pressure (similar to mud cracks).
A closer look reveals how far this process can go without leading to remineralization and the replacement of original minerals by new ones (e.g., pyritization or chloritization) as new elements are introduced by hydrothermal circulation.
The lighter areas in Fig. 6 are probably quartz recrystallized from sand grains whereas the darker zones are very likely quartz and muscovite that result when water is removed from clays. The heat and pressure weren’t sufficient to form new mineral crystals with larger size, however, so the mixed mud-sand assemblage remains identifiable.
These rocks were folded during compression, when some of the faults certainly occurred. We saw an outstanding example in a road cut (Fig. 7).
Figure 7B has original bedding highlighted. This shows a tight fold on its side (recumbent) and juxtaposed against vertical bedding. There are certainly some faults present between these layers. The rocks were brittle enough (i.e. shallow burial) to break and slide against one another. Zooming in closer on the “C” in Fig. 7C, we see that there was no remineralization in these tightly folded rocks (Fig. 8).
But if we look at the more outward layers surrounding this structure, we see signs of substantial brittle fracture (Fig. 9) and remineralization. The former is shown by the small size of (much less than 1 foot) of individual blocks of stone (Fig. 9A) and the latter by the weathered appearance and lack of structure in some areas (Fig. 9B).
Soon after this we left the central mining district and the rocks deposited and deformed during the collision of Tasmania with Gondwana (~500-370 MY). In the case of Tasmania, the Continental Divide is between the rainy western half and the dry eastern half. Another way to look at it is that the western half was created when Gondwana was formed and the eastern half when it was pulled apart.
And finally, the King William Range, comprising peaks of fault blocks pointing to the east and a different geologic regime…
The Tripartite Organismic Stimulus-Response Cortical Augmentation model (TOSCAM) consists of four components so far: the human body; the subconscious; the conscious mind; and as-yet undefined stimuli, which I temporarily referred to as qualia. This post will explore this last component in more detail.
I did some more reading and discovered that perception is conceivably more complex than simply seeing or hearing something. Philosophers have constructed many theories to try and understand what we see, etc., including the physicalist model, which (greatly simplified) proposes that nothing is going on in our mind. A signal, like the light spectrum from an object we are viewing, is processed into a series of neurons firing and sending a representation of the object to our prefrontal cortex, where it is perceived as it really is. That sounds pretty straightforward, but someone pointed out the existence of hallucinations and other phenomena like phantom limbs, that aren’t representations of anything a person is experiencing. One concept that grew out of this discrepancy is Sense-Datum Theory.
Vastly oversimplified, Sense-Datum Theory proposes that sense data consist of both content and intrinsic non-representational features (e.g., blobs of paint comprising a painting). This latter signal is what is called a quale (qualia is the plural). Unfortunately a quale can’t be measured and is nothing more than a hypothetical construct, so there’s a lot of controversy associated with the idea. For example, many philosophers treat it as the sensation of perceiving (e.g., how does it feel to “see” red).
Here’s an interesting summary from the Stanford Encyclopedia of Philosophy (see note 3): “…we still seem to be left with something that we cannot explain, namely, why and how such-and-such objective, physical changes…generate so-and-so subjective feeling, or any subjective feeling at all…Some say that the explanatory gap is unbridgeable and that the proper conclusion to draw from it is that there is a corresponding gap in the world. Experiences and feelings have irreducibly subjective, non-physical qualities…There is no general agreement on how the gap is generated and what it shows.”
To muddy the water even further, here’s another interesting comment on qualia as representational: “If I feel a pain in a leg, I need not even have a leg. My pain might be a pain in a phantom limb. Facts such as these have been taken to provide further support for the contention that some sort of representational account is appropriate for qualia.”
I was going to drop the concept of qualia in my model and instead use a concrete word like sense-datum as the information-carrying medium for perception and let the philosophers argue about the details. However, I’m not going to be publishing my model in any peer-reviewed journals and I like the idea of a simple word rather than a phrase. I’ll keep qualia with the caveat that it is being used in a representational sense. I accept “some sort of representational account” as good enough for my purposes.
Without espousing Sense-Datum Theory, I am going to use the following definition of a quale (actually a sense-datum): an immediate object of perception, which is not a material object; a sense impression. I’m only using the concept, not the theory. In fact, neither quale nor sense-datum are very useful because they leave us with a vague concept of something we are aware of (perception) and not how the perception was created. How is a quale (sense-datum) created? (I’ll use the parentheses in this post only.)
Let’s think of the brain as a computer network. This is an old idea and it isn’t particularly applicable; after all, there are no main network cables within our heads but instead trillions of axons connecting every neuron to practically every other neuron with an uncountable number of intermediate neurons between them. We can get around this gross oversimplification by introducing the idea of a virtual network. For example, perceiving an object (philosophers like to use tomatoes) is the result of a complex process that turns the electrical signals from over 100 million rods and cones into an image, which is then identified, cross-correlated, and delivered to our prefrontal cortex, ready to be acted on. We may cut the tomato up or put it in the refrigerator for later use. However, those millions (who knows how many) of neurons are firing synchronously to deliver the total package of what we perceive as a “tomato.” I’m calling this organized firing of millions of neurons a virtual network (VN). A virtual network isn’t static. For example, here are some neural frequencies during different mental states.
|Beta (β)||12–35 Hz||Anxiety dominant, active, external attention, relaxed|
|Alpha (α)||8–12 Hz||Very relaxed, passive attention|
|Theta (θ)||4–8 Hz||Deeply relaxed, inward focused|
|Delta (δ)||0.5–4 Hz||Sleep|
These data suggest that any given VN (say, that associated with looking at a tomato) is at risk of being deleted as often as 35 times per second, and at best lasts a couple of seconds. Obviously, we can hold a thought or perception longer than this; what this implies is that any specific quale (sense-datum) must be refreshed or updated continuously or it will be replaced by something new (perhaps a carrot lying next to the tomato).
To complete the network analogue for the TOSCA model, we need to define qualia in more detail. The digital model of bits (binary device that can be on or off, 0 or 1, etc.) seems appropriate to describe the smallest unit of information transfer among neurons, which are either on or off. Some arbitrary number of neurons firing in unison as part of generating a quale (sense-datum) is somewhat analogous to a byte for the TOSCA model. In most computer applications, a byte consists of eight bits. This is the smallest unit of storage in computer memory, but we don’t have that restriction in the brain. Nevertheless, it is a useful concept because a byte is not sufficiently large to generate the perception of a tomato. For example, a few dozen neurons (bits) could form a byte that contains information only about the color of the tomato, and other bytes would encode other characteristics (e.g., location in space, roundness, softness).
To assemble a quale (sense-datum) for the perception of an object, thought, emotion, etc, we need to organize all those bytes coming in from millions of neurons over the VN. This can be done using the concept of a packet borrowed from digital networking. A packet contains both data and information about how it should be decoded, a perfect idea for the model. For example, groups of bytes can be virtually organized into packets that contain shape information, etc, and telling the receiving part of the brain (e.g., the prefrontal cortex) which ones go together. No one has a clue how this is done. It is an abstract concept even in brain research. We only need the concept to continue; and with the idea of multiple packets arriving from different brain areas with information about what they contain, a quale (sense-datum) can be perceived.
This has been a moderately technical post, but it was necessary to have a complete concept for the TOSCA process before applying it to real-world examples. The next post will focus on visual perception and how it can be studied, using introspection to examine and control qualia, or sense-data.
Qualia. Stanford Encyclopedia of Philosophy. First published Wed Aug 20,
Huemer, Michael, “Sense-Data”, The Stanford Encyclopedia of Philosophy (Spring 2019 Edition), Edward N. Zalta (ed.).
Franklin pushes the handle of the mop submerged in the suddenly heavy mop bucket filled with water and floor cleaner past the nurses station into the emergency room, feeling like sitting down in one of the plastic seats. He doesn’t do it because he’s a little behind schedule after spending fifteen minutes in the custodian room at the beginning of his shift, recovering from the ten-minute walk from the bus station to the hospital. Arriving at his destination in the vending area, he begins to mop the floor stained and sticky from coffee and soda as the emergency room explodes into activity.
Several gurneys are wheeled in by orderlies with doctors and nurses appearing suddenly to attend to the half-dozen men and women suffering from gunshot wounds during a gunfight less than a block from the hospital. He’s seen this enough that he keeps working, until he recognizes one of the victims’ pleading voice as his son’s. He drops the mop and hurries after the group that has gathered around Joseph, sixteen-years old and a good student, who isn’t involved with gangs.
“He’s my son,” Franklin tells the nurse as she tries to prevent his entering the room where Joseph is being moved from the gurney to the bed by two orderlies, a nurse, and a doctor. He is pushed away from his son’s bed by the sheer volume of the doctors and nurses trying to save Joseph’s life. He resigns himself to waiting in the hall and continues mopping the floor, which is better than the large group gathering in the waiting room, some of them covered in blood. He doesn’t like the look of some of the young men he notices as he takes his bucket and mop to continue his work in another corridor. He’s accustomed to changing his mopping schedule in the inner-city hospital where people seem to find ways to injure themselves, even without guns, in the middle of the night.
Franklin forgets to call his wife and tell her about Joseph’s arrival at the ER because he’s distracted by the pain in his chest and his arm. “It doesn’t matter,” he tells himself. “There’s nothing she can do for Joseph and I’ll call her with the good news when Joseph is recovering.” Thus consoled, he finds that mopping the floor keeps his mind from wandering to the room where Joseph is lying unconscious, so he forgets about the nightmare he is experiencing. When he finishes mopping the floors in the rooms connected to the corridor, it’s time to replace the antibacterial mixture in his bucket. He’s dreading retracing his steps back to the custodial closet, past Joseph lying in a bed, and past the noisy group still gathering in the ER waiting room.
He enters the ER and goes to see how Joseph is doing. He has no problem now that there aren’t so many nurses and doctors getting him stabilized but when he looks behind the curtain, Franklin discovers that a young girl has replaced his son on the bed. She has tubes connected to her arm and an oxygen mask, but none of the machines is making a disconcerting sound, so he quietly slips out and goes to the nurses station, where Mary greets him with a worried expression.
“I guess Joseph is out of danger and in a regular room now,” he says with relief.
Mary shakes her head imperceptibly and, with tears filling her eyes, says, “I’m sorry, Franklin…I’m so sorry. I can’t believe it…I just can’t believe it…”
Franklin stumbles backwards and falls to his knees but doesn’t collapse from the pain in his chest. Mary rushes around the counter and asks him if he’s feeling ill and, as she helps him back to his feet, he stammers, “It’s such a shock to lose Joseph… I have to call my wife and tell her about it. I’m going to do that now.”
Mary watches Franklin ponderously push his mop bucket past the waiting area as the noise of the crowd suddenly increases in ferocity. Franklin is awakened from the stupor brought on by guilt and pain and looks up as several male voices make challenging and even threatening statements, which are answered by shrieks and profanity from the people closest to a young man who suddenly pulls a large pistol from his pocket and points it at an older man standing in front of him.
Without thinking, Franklin pulls the mop out of the bucket and ignores the pain in his chest as he raises it over his head and rushes forward. The heavy, wet mop sends the gun crashing to the floor as Franklin falls in a heap to the linoleum tile. He smiles as the gunman is knocked down by the force of the crowd.
In Chapter Two, I laid out the basic outline of the psychological DDJ model these posts are exploring. It’s time to invent an acronym, as much as I personally dislike alphabet salad, because it’s too cumbersome to keep repeating a long name and standardization has a lot of advantages. Let’s review the components to get started.
The model I’m developing comprises (so far) four components: modules representing the body, the subconscious, and the conscious; and another ambiguous category that the DDJ calls Vital Breaths. That’s a pretty simple model, but I’m sure it’s going to get more complex as I delve into it. Nevertheless, we need a name, and it isn’t going to include a word that could mislead some to think that there is any spiritualism involved. I’m not going to use DDJ words (ambiguous translations from ancient Chinese), so perhaps it would be useful to summarize the three observable components (body, subconscious, and conscious) into a single concept like tripartite, which means split into three parts. That’s pretty easy to remember. There is no way Vital Breaths is going into the name, so we need something more precise than a two-millennia-old definition from before the invention of PET and fMRI instruments, not to mention all of the other tools used by neuroscientists in the modern world.
Qualia are defined as: “the internal and subjective component of sense perceptions, arising from stimulation of the senses by phenomena.” That’s pretty simple and unambiguous, but it doesn’t quite meet the needs of the model I’m developing because it only refers to sensory input; what we need is a more general concept that will include homeostatic mechanisms as well. Homeostasis uses biochemical factors, DNA transcription networks, bioelectricity, and other physical forces to regulate the cell behavior and large-scale patterning during embryogenesis, regeneration, cancer, and many other processes. Sensory input and homeostasis both operate as stimulus-response processes; a signal is received by a cell, organ, etc, and the system responds.
So far, we have tripartite and stimulus-response. This is primarily a psychological model, but it will be indirectly applicable to the body as well (recall the fourth component); thus, we’ll throw in organismic to explicitly define it as a biological model.
The primary mechanism to which the model can be applied is Cortical Remapping. Cortical maps consist of adjacent neurons within the cortex that are direct (spatial) representations of parts of the body, images from the retina or memory. They can be strengthened and enlarged through reinforcement, whereby connections between the body, subconscious, and mind can be altered and (presumably) augmented as evidenced by learning.
We have identified all of the components of a psychological model based on the ancient wisdom of the DDJ, but updated to be understood and applied by modern people.
For the rest of these posts I will refer to this process as Tripartite Organismic Stimulus-Response Cortical Augmentation (TOSCA) and the model as TOSCAM.