David Williams finds natural history stories wherever he looks. He's incorporated some of them into his new book, "The Street-Smart Naturalist - Field Notes from Seattle." Naturally, his background as a geologist always draws him to rocks. Rocks are everywhere. Look for them instead of brains in the knucklehead who cuts you off on I-5. And of course they're in mountains. But they're also under our feet and in our buildings.
"In 1993, the city did an inventory of cobblestone streets in Seattle," writes Williams. "They found 94 of them. Queen Anne has about one-third of those streets." Sandstone cobbles were a popular road-paving material in Seattle from the 1890s to the 1910s.
Chuckanut sandstone was the most common variety of rock used for street cobbles. It came from quarries in Wilkeson and around Bellingham. According to Williams, the rock is about 50 million years old. "Judging from the fossils found within the Chuckanut," he notes, "geologists believe that a sub-tropical climate dominated at one time. Palm trees, swamp cypresses, and tree-sized ferns grew in a moist (40-100 inches of rain), bayou-like environment." By 38 million years ago, "cooler conditions prevailed, replacing the previous forest with willow, maple, sycamore and conifers - trees that could withstand freezing temperatures."
Sandstone was preferred for cobbles over other types of rock because it cut easily and provided better traction for horses. And even though rain, wagons and shod hooves wore down the stones, they were better than the mud or wood of the past. "Street pavers also used Index granite for roads and curbs," Williams observes, "and it can still be found on many corners in older parts of Seattle." As the use of reinforced concrete grew, it began to appear in place of the granite. Given how city engineers worked to harden street corners 100 years ago, it's ironic that many of these hardened street corners are being removed and replaced with sloping ramps.
"Only a handful of these historic streets remain in Seattle," Williams ruefully writes. "Most have been paved over, their stories lost to drivers who don't want the jarring ride." Williams doesn't mind the hard ride: "I like the connection to the past and consider it a privilege to drive over the ancient cobbles - though I try to take these roads when no else is in the car with me!" -P.S.
[[In-content Ad]]
