Minggu, 20 November 2011

Detour to the Divide

Leaving our Littleton, Colorado, farm early yesterday morning, low clouds obscured the finale of the annual Leonid meteor shower. The clouds and chilly air were courtesy of a northeast, upslope wind behind a cold front that had pushed across the Front Range overnight.

The prospect of driving across the Plains beneath this low ceiling prompted a detour to the south and I followed US 85 and then I-25 to Colorado Springs. Crossing the Palmer Divide at Monument Hill, just north of the Air Force Academy, I left the clouds behind and descended through the Fountain Creek Valley under sunny skies. Once in the city, I turned east on US 24 and drove across the south flank of the Palmer Divide all the way to Limon, watching the cloud bank lap against the crest of the ridge like an angry sea.

An erosional remnant, the Palmer Divide consists of Tertiary deposits overlying a Cretaceous base. Stretching nearly 70 miles from west to east, it connects the foothills with the High Plains escarpment and separates the watersheds of the South Platte and Arkansas Rivers. Elevations along the crest of the Divide range from 7500 feet at its junction with the foothills to 6500 feet where it merges from the High Plains, northeast of Limon. This geophysical barrier plays a significant role in the regional weather, catching upslope precipitation from the north or south, igniting thunderstorms and granting either Denver or Colorado Springs downsloping winds that warm the air and clear the skies.

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