A fall line (or fall zone) is a geomorphologic unconformity (e.g., monoclinal faulting or flexing) between an upland region of relatively hard crystalline basement rock and a coastal plain of softer sedimentary rock. A fall line is typically prominent when crossed by a river, for there will often be rapids or waterfalls. Many times a fall line will recede upstream as the river cuts out the uphill dense material, often forming “c”-shaped waterfalls. Because of these features riverboats typically cannot travel any farther inland without portaging, unless locks are built there. On the other hand, the rapid change in elevation of the water, and the resulting energy release, makes the fall line a good location for water mills, grist mills, and sawmills. Because of the need for a river port leading to the ocean, and a ready supply of water power, settlements often develop where rivers cross a fall line.
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Famous quotes containing the words fall and/or line:
“Here’s neither bush nor shrub to bear off any weather at all. And another storm brewing, I hear it sing i’ the wind. Yond same black cloud, yond huge one, looks like a foul bombard that would shed his liquor. If it should thunder as it did before, I know not where to hide my head. Yond same cloud cannot choose but fall by pailfuls.”
—William Shakespeare (1564–1616)
“The man of business ... goes on Sunday to the church with the regularity of the village blacksmith, there to renounce and abjure before his God the line of conduct which he intends to pursue with all his might during the following week.”
—George Bernard Shaw (1856–1950)