It is difficult to fathom the journey that the original sediments have gone through for over 400 million years to disclose the conglomerate rock layering we see and range upon in the Gunks. Even apart from its geological contortions and spellbinding drama of formation, we have little sense for the reach of time involved in this creation story. As every leaf in a forest is available to disclose an entire universe of teeming activity in the neglected depth of its otherwise two-dimensional space— (for indeed, the leaf’s nearly infinite biochemical world is also crowded with the astonished gaze of the ecologist, biologist and poetic philosopher)— so also the layered depths of Shawangunk conglomerate reveal much more than an impenetrable block of frozen time. And though the rock presents its hardness as more than a superficial glaze upon an inert substance— reasserting ‘hardness’ over and above a purely relational quality of language and back into the full solidity of a perceptual bearing— the rock is by no means, thereby, brute.
The Gunks story began prior to the laying down of its conglomerate layers. As the remnants of an ancient ocean plunged beneath the continent into molten fires so as to prepare for rebirth, a massive mountain range grew from a leading edge of offshore volcanic islands colliding with the slowly gathering mass of continents. The ancient mountains (whose roots lie in the nearby Taconics) reached a height of well over 10,000 feet. In the deep squeeze of subduction and the mountain building cycle that followed, silicates were cooked and then cooled at a rate for quartz crystals to precipitate and disperse within the rock matrix.
In time, that great Taconic range would itself erode and crumble, tumbling their forged sediments into braided streambeds flowing into a broad inland sea that lay in wait. The quartz sand and pebbles rounded in the overburdened streams that subsequently deposited their load into the sediments along the way to the inland sea. It is this combination of eroding mountain material and sand that contributed directly to the cemented quartz sediments we often stand upon in the form of layered Gunk conglomerate. Like all creation stories, however, this was only the beginning of a larger narrative. Many geologic features do not last nearly as long as Shawangunk conglomerate before being altered in composition or recycled into magma through plate tectonics. The conglomerate sediments that we witness were laid down roughly 420 million years ago. Not only have the rocks endured, they have been further pressurized, tempered, infused, buckled, tilted, and polished in an enduring initiation ceremony that lasts up to this day.
For rock, the extended initiation is but preparation for death and rebirth, spanning an entire geologic lifespan. Some 350 million years ago, with Shawangunk conglomerate already cementing its quartz cargo through the pressure and depth that had amassed for over 70 million years, the great gathering of continents that would later form the supercontinent of Pangaea ramped up in earnest. One of the first waves included the so-called Acadian orogeny, which caused the Acadian Mountains to rise in what is now New England, and buckled the Gunks into the classic ridge system we observe, with its ridges and valleys running longitudinally. This event also lifted the entire region from its watery origins and set the stage for the later creation of the neighboring Catskill Mountains by building up the Acadian Mountains that would later erode into a raised delta deposit, which would, in turn, erode into the Catskills. In that sense, both the Shawangunks and the neighboring Catskill Mountains present novel transformations of raw material from ancient mountain erosion material— albeit of two different ancient mountains.
The quest toward the great Pangaea supercontinent was not done however. Approximately 270 million years ago, the tectonic activity entered another phase, the Alleghenian orogeny— raising the Appalachian Mountains to a height well above the present day Rockies, and tilting the entire cemented layering of the Shawangunk ridge at an upward angle to the east. In the long center seam of the massive supercontinent that was Pangaea, mountains rose even higher than the present day Himalayans. Eventually, with the subsequent volcanism and violence of Pangaea’s break up, our own Atlantic Ocean would begin its adventure into existence, beginning perhaps some 200 million years ago. All the while the laying down of bedded layers and thick sediments continued to bury the durable Gunk conglomerate with the limestone and sandstone sediments that were added to the Catskill plateau before eroding into the precursors to the deep valleys and mountains we know today as the Catskill Mountains. It was the repeated bulldozing action of more recent glaciation that added the final touch. At the end, the jostling Catskill Mountains were formed to the north and west of the submerging Gunks conglomerate, as Rosendale limestone also lay atop the conglomerate closer to its submersion. Rosendale limestone was, of course, later quarried into caves during the modern rise of industry.
One has to stand upon a Shawangunk ridge to look not outward into the surrounding valleys, but upward, so as to visualize the formative power of a mile-high glacier reaching over twice the height of the Gunks’ pinnacles. Even so, one’s feet have already deciphered the striations, grooves and characteristic echo pattern and chatter marks that have been etched into the polished conglomerate surfaces, like hieroglyphics written boldly and without secret coding throughout the region. Glaciation repeated its crescendo-decrescendo pattern some two to three million years ago, in a manner similar to the pulses that arose hundreds of millions of years prior (by virtue of a different arrangement of continents and astronomical conditions).
The most recent period of glaciation included the so-called Wisconsin ice sheet— which started to build up only 85,000 years ago and reached a maximum height around 25,000 years ago — only to recede a mere 10 to 12 thousand years ago; leaving the underlying topography roughly as we see it today.
If we could view The Trapps in a massive cutaway similar to the way geology professor and illustrator Jack Fagan depicted in his classic guide: Scenes and Walks in the Northern Shawangunks, we would have a better sense for the relationship of Undercliff and Overcliff Carriageway. As witnessed from Near Trapps on the other side of the fault that Route 44-55 has followed— a simplified cross-section of The Trapps ridge would reveal Shawangunk conglomerate bowing upward like a stacked rainbow of bedded layers. The fractured and aggressively tilted stacking of 420-million-year-old layers have been sheared in half before rounding and sweeping downward to finish their arc on the other side. They now present a partial sector that has been abruptly cut at the apex of the bow on the eastern front. Undercliff Carriageway runs longitudinally beneath the sliced edge of the conglomerate arch and talus debris on the eastern side. A bed of Martinsburg shale that is older and much thicker than the overlying conglomerate cap rock has been warped and twisted, providing sloped footing for Undercliff Carriageway— as well as the soil to sustain a more organized forest upon its slopes. In Block Party, we experienced some of these features firsthand as we traversed part of the Undercliff Carriageway. On the other side of the ridge, the largely intact western side of the broken bow of The Trapps ridge houses Overcliff Carriageway traversing longitudinally as a tiny contoured lip trimming the main axis of the ridge. The western bow upon which it situates has not been sheared in half in the dramatic manner of the eastern front. Overcliff Carriageway is thereby placed directly upon the bowed and then tilted angle of the conglomerate arch itself. Looking down toward the origin of its rise, the caprock falls away with continuity from Overcliff’s flank, into the broad Clove Valley to the west— toward the Coxing Kill waters flowing in its crease.
This overview will provide a useful schematic to structure our awareness through the Gunks. But like every conceptual schema, it must be planted firmly in a real physical experience in order to avoid withering and remaining devoid of life. Like wild blueberries, no set of facts float freely and completely isolated for the plucking— all are part of a parent structure that is already firmly rooted in the physical. As we discuss below, in the Gunks, that parent experience has its characteristic qualities based on the geological foundation that we have outlined, and the ecological dynamics that conform to the mandate of selecting only that vegetation that can adapt to the region’s acidic and sparse soil, except where the rock has been broken or interrupted to allow rich regions of Martinsburg-derived fertility to rise up in between.
This selection constraint imposed on growth sounds both harsh and stark to the intellect, but the basic irony at the level of the senses discloses a rich and unambiguous set of contrasts. The senses are always poked with a fundamental oddness by virtue of this relationship. The bass chord and backbone of that oddness is the bleached conglomerate itself. As one of the hardest of rocks, quartzite conglomerate is more resistant to erosion than granite. A thin soil of quartz particles mixed with humus and organic residue is all that the conglomerate offers. Despite this depravity, pitch pines are capable of rooting their bedding planes through cracks and fissures in the rock. Lacking mineral nutrients and their associated buffering power, the thin film of soil that does develop is both acidic and undernourished. All but the appropriately adapted species of hardy vegetation are incapable of withstanding the harsh selection process. Pitch pine forests— often dwarfed in stature and gnarly of form— share their spacious and sculptured platforms with woody shrubs such as mountain laurel, wild blueberry and huckleberry.
Fields of white bedding with variably raised and tilted flooring thrust angled stages designed to introduce spontaneity in the form of dwarf pines and huckleberry upon the ever-varying exhibitions. Starkness is captured sculpturally through a crisp display that frequently changes even though every new exhibition is a variation of the same basic formula. In the valleys, saddles, and wide faults that hollow out the ridgeline topography and interrupt the conglomerate bedding, exposed Martinsburg shale makes its shortened life span count as it gives itself over to a thick bedding of soil. It thereby nourishes a greater diversity of life with the nutrients of its broken body. Here again, we might experience the moist coolness of a mixed hemlock and hardwood forest supported by that richer soil, but we add another dimension to the experience when we consider that the Martinsburg shale is the deep basin deposition from a truly ancient sea that developed during an equally deep time. When the Iapetus Ocean— ‘Father of the Atlantic’, was being closed out of existence with the gathering of Pangea, the muddy depositions that would later become Martinsburg shale piled up thousands of feet high. The very breath that we take in the cool shadows and moist glens where hemlocks grow large in the Gunks may thus be considered the renewed life of that ancient deposition by virtue of the minerals that have been recycled in the living forms whose respired air we now inhale. Such cool, refreshing air is widespread in the Gunks, and we will discover that it arrives at a time when dryness or heat threatens to undermine our tolerance.