The Pennsylvania Turnpike crosses over and through a number of different geologic formations and structures. Road cuts reveal the interiors of the mountains, showing layers of rocks that appear vertical in some places and bent into curves in others. The geologic section of Pennsylvania (and other parts of the Appalachians from New York to Alabama) that comprises “waves” of rocks is known as the Valley and Ridge Province. The province resulted from the convergence of the African and North American tectonic plates.
The “waves” are composed of downward warped rocks and upward warped ones of once-horizontal sedimentary layers lying in low elevations. “U”-shaped rocks make wave troughs and are called synclines, whereas upside-down “U”s make wave crests and are dubbed anticlines. Many of the rock-wave troughs ironically form elongate ridges that parallel one another on either side of valleys cut into anticlines.* In most places, only parts of the rock-waves are visible, showing diagonal or vertical to near-vertical layers of sandstone, shale, and limestone. The bending of Valley and Ridge rocks into waves took millions of years and occurred before the first dinosaur walked the land, and it built mountains that would rival the elevations of today’s highest ranges.** Think about it: The pressure of convergence elevated the land into lofty mountains.
The rock-waves show that Earth’s seemingly rigid materials, its rocks, can bend with sufficient force, even if they bend only in pulses of warping over a long time. But note: Not all that is brittle bends. Offset layers of bent rock layers in the Valley and Ridge reveal an occasional break, a fault, and offsetting isn’t the only product of faulting. The grinding of opposite sides of a fault can produce a breccia, a layer of jagged rock fragments that fills a fault. Nevertheless, bending without breaking dominates faulting in the province; the region is more bent than broken.
In a way, human convergence can mirror the rocks of the Valley and Ridge: Sometimes bent by pressure; sometimes broken and fragmented. When we have little to lose, we’ll bend a little, and the bending can even elevate us to an altitude of mutual altruism. When we consider our so-called core ideas, our ideology, however, we often find ourselves incapable of any plasticity.
Take extremists of any bent, for example. Their ideologies are rigid, so their positions are usually inflexible. Frustrated that bending doesn’t occur, people of opposing ideologies apply force that results at best in filling the boundary between the two with a breccia of both ideas and ideologues. An inflexible ideology appears to be harder to bend than solid rock. Look, for example, at the centuries-old resistance to change in conflicts between Sunnis and Shia, Protestants and Catholics, Christians and Muslims, Hutu and Tutsi, and, go on, you can name many other opposing groups, including, possibly, you and some relative or neighbor, some rival gangs, or even some rival socioeconomic classes. People often resist bending until either they break or their opponents fragment.
Could we learn something from “rock-waves”? Ideologues bend very slowly if at all because their core ideas have little plasticity. Rather than bend with the forces of opposition to form lofty mountains of compromise and mutual altruism, they resist until nothing but rubble fills the gap. Whereas geologic history records more bending than faulting, human history records more faulting than warping. That’s a shame. The dominance of “rock-waves” in the Valley and Ridge indicates that rocks appear to be more flexible than humans.
* Sideling Hill lies in both Maryland and Pennsylvania and is an example of a synclinal mountain; see pics at
https://images.search.yahoo.com/yhs/search?p=pics+of+sideling+hill&fr=yhs-Lkry-SF01&hspart=Lkry&hsimp=yhs-SF01&imgurl=http%3A%2F%2Flh3.googleusercontent.com%2F-MBG90YCMXgo%2FVdM8jBjMKxI%2FAAAAAAABFxs%2FjiLsJmM8KoU%2FSideling-Hill-Road-Cut-21%2525255B6%2525255D.jpg%3Fimgmax%3D800#id=1&iurl=http%3A%2F%2Flh3.googleusercontent.com%2F-MBG90YCMXgo%2FVdM8jBjMKxI%2FAAAAAAABFxs%2FjiLsJmM8KoU%2FSideling-Hill-Road-Cut-21%2525255B6%2525255D.jpg%3Fimgmax%3D800&action=click
A small fault can be seen near the top.
** More than 200 million years of erosion have reduced the elevations of Valley and Ridge mountains.
The “waves” are composed of downward warped rocks and upward warped ones of once-horizontal sedimentary layers lying in low elevations. “U”-shaped rocks make wave troughs and are called synclines, whereas upside-down “U”s make wave crests and are dubbed anticlines. Many of the rock-wave troughs ironically form elongate ridges that parallel one another on either side of valleys cut into anticlines.* In most places, only parts of the rock-waves are visible, showing diagonal or vertical to near-vertical layers of sandstone, shale, and limestone. The bending of Valley and Ridge rocks into waves took millions of years and occurred before the first dinosaur walked the land, and it built mountains that would rival the elevations of today’s highest ranges.** Think about it: The pressure of convergence elevated the land into lofty mountains.
The rock-waves show that Earth’s seemingly rigid materials, its rocks, can bend with sufficient force, even if they bend only in pulses of warping over a long time. But note: Not all that is brittle bends. Offset layers of bent rock layers in the Valley and Ridge reveal an occasional break, a fault, and offsetting isn’t the only product of faulting. The grinding of opposite sides of a fault can produce a breccia, a layer of jagged rock fragments that fills a fault. Nevertheless, bending without breaking dominates faulting in the province; the region is more bent than broken.
In a way, human convergence can mirror the rocks of the Valley and Ridge: Sometimes bent by pressure; sometimes broken and fragmented. When we have little to lose, we’ll bend a little, and the bending can even elevate us to an altitude of mutual altruism. When we consider our so-called core ideas, our ideology, however, we often find ourselves incapable of any plasticity.
Take extremists of any bent, for example. Their ideologies are rigid, so their positions are usually inflexible. Frustrated that bending doesn’t occur, people of opposing ideologies apply force that results at best in filling the boundary between the two with a breccia of both ideas and ideologues. An inflexible ideology appears to be harder to bend than solid rock. Look, for example, at the centuries-old resistance to change in conflicts between Sunnis and Shia, Protestants and Catholics, Christians and Muslims, Hutu and Tutsi, and, go on, you can name many other opposing groups, including, possibly, you and some relative or neighbor, some rival gangs, or even some rival socioeconomic classes. People often resist bending until either they break or their opponents fragment.
Could we learn something from “rock-waves”? Ideologues bend very slowly if at all because their core ideas have little plasticity. Rather than bend with the forces of opposition to form lofty mountains of compromise and mutual altruism, they resist until nothing but rubble fills the gap. Whereas geologic history records more bending than faulting, human history records more faulting than warping. That’s a shame. The dominance of “rock-waves” in the Valley and Ridge indicates that rocks appear to be more flexible than humans.
* Sideling Hill lies in both Maryland and Pennsylvania and is an example of a synclinal mountain; see pics at
https://images.search.yahoo.com/yhs/search?p=pics+of+sideling+hill&fr=yhs-Lkry-SF01&hspart=Lkry&hsimp=yhs-SF01&imgurl=http%3A%2F%2Flh3.googleusercontent.com%2F-MBG90YCMXgo%2FVdM8jBjMKxI%2FAAAAAAABFxs%2FjiLsJmM8KoU%2FSideling-Hill-Road-Cut-21%2525255B6%2525255D.jpg%3Fimgmax%3D800#id=1&iurl=http%3A%2F%2Flh3.googleusercontent.com%2F-MBG90YCMXgo%2FVdM8jBjMKxI%2FAAAAAAABFxs%2FjiLsJmM8KoU%2FSideling-Hill-Road-Cut-21%2525255B6%2525255D.jpg%3Fimgmax%3D800&action=click
A small fault can be seen near the top.
** More than 200 million years of erosion have reduced the elevations of Valley and Ridge mountains.
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