The water in a river does not flow at equal speeds. Nowhere along a stream’s path is the variable speed more evident than along the inside of a meander. Water on the outside of a bend travels faster than water on the inside because the circumference of the turn is longer than it is on the inside. You don’t need a current meter to discover this principle. The river reveals it in two dramatic ways.
First, the faster moving water on the outside of the meander erodes the river’s banks more efficiently than water on the inside. The result is an “undercut” slope, usually an almost-to-virtually vertical bank, whereas the slope of the bank on the inside of the turn is a usually gentler “slip-off” slope. Second, scouring work on the outside of a meander is countered by a crescent-shaped deposit of sediments on the inside. A faster current has the energy to move objects and erode more efficiently than a slower one. The crescent-shaped deposit is a point bar.*
In some ways cultures are like streams meandering through time. Fast-moving controls, such as political and religious movements, coups, and wars, undercut the containing barriers of tradition and alter its course. But every erosive event is accompanied by a slower movement, a flow that cannot carry its burden efficiently and that shapes the channel of time not by cutting, but rather by depositing little by little what it cannot carry away. That accumulation of cultural sediment migrates into the stream channel, gradually filling in a place that one brief moment of undercutting had eroded.
Erosive events capture our attention. They are dramatic shapers of culture, and they highlight our history books. But all of us are equally shaped by the slow accumulation of culture, the gradual changes that leave their deposit on the landscape of our minds and alter our values and behavior. And, although you might believe you ride the faster current of rapid change, you also play a role in establishing a point bar. Even when you think not much is happening, you and your contemporaries are contributing to the buildup of cultural sediment that manifests itself after the flow has passed it. Yes, there is undeniable variability in currents, but the channel carries water identifiable as a single stream.
https://offtheshelfedge.files.wordpress.com/2011/08/geology-on-the-wing-4.jpg
First, the faster moving water on the outside of the meander erodes the river’s banks more efficiently than water on the inside. The result is an “undercut” slope, usually an almost-to-virtually vertical bank, whereas the slope of the bank on the inside of the turn is a usually gentler “slip-off” slope. Second, scouring work on the outside of a meander is countered by a crescent-shaped deposit of sediments on the inside. A faster current has the energy to move objects and erode more efficiently than a slower one. The crescent-shaped deposit is a point bar.*
In some ways cultures are like streams meandering through time. Fast-moving controls, such as political and religious movements, coups, and wars, undercut the containing barriers of tradition and alter its course. But every erosive event is accompanied by a slower movement, a flow that cannot carry its burden efficiently and that shapes the channel of time not by cutting, but rather by depositing little by little what it cannot carry away. That accumulation of cultural sediment migrates into the stream channel, gradually filling in a place that one brief moment of undercutting had eroded.
Erosive events capture our attention. They are dramatic shapers of culture, and they highlight our history books. But all of us are equally shaped by the slow accumulation of culture, the gradual changes that leave their deposit on the landscape of our minds and alter our values and behavior. And, although you might believe you ride the faster current of rapid change, you also play a role in establishing a point bar. Even when you think not much is happening, you and your contemporaries are contributing to the buildup of cultural sediment that manifests itself after the flow has passed it. Yes, there is undeniable variability in currents, but the channel carries water identifiable as a single stream.
https://offtheshelfedge.files.wordpress.com/2011/08/geology-on-the-wing-4.jpg
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