Claremont Potatoes!
Stroll through Claremont and you’ll see them everywhere – forming building foundations and facades, decorating gardens, lining paths, framing signs, and making up fireplaces and chimneys.
But what are they, and where did they come from?
Claremont Potatoes started out as large boulders in the San Gabriel Mountains to the north. These boulders built up over millions of years throughout the Pomona Valley. They were formed primarily of granite from the Mesozoic period (65 to 245 million years ago).
Image caption: Granite is a light-colored igneous rock with large visible grains of quartz, feldspar, mica, and other minerals, formed during the cooling of molten rock.
Claremont lies on an alluvial fan formed by two main creeks, San Antonio Creek and Cucamonga Creek, along with many smaller ones. This fan starts in the mouth of San Antonio Canyon, and widens to the south. Over time, the creeks carried the granite boulders downstream. Along the way, they were broken up and rounded out to the size they are now before being dropped in Claremont.
Image caption: An alluvial fan is a flat, triangle-shaped area where flowing water deposits rocks and soil.
Claremont Potatoes vary in size from, well, potato-size, to bowling ball-size, and even larger. So why are they called Potatoes? It’s because early settlers to the area, when clearing the land to build homes and plant orchards, found that the rocks in the soil were as abundant as a potato crop.
In fact, there were so many Claremont Potatoes that in 1915, LA County proposed helping out-of-work men by hiring them to smash Claremont’s rocks into gravel, which the county would then buy to make roads. It was back-breaking work, and of the 240 men who started work the first Monday, only 30 remained on the job by the end of the week. The program was short-lived, but the Claremont Potatoes remained!
Image caption: The workers broke Claremont Potatoes into gravel by hand, using sledgehammers and working 10-hour days.
Alluvial fans are prone to flooding and in fact the floods of 1938 and 1969 caused widespread damage to the Claremont area. Now both main creeks of the Pomona Valley are tamed by flood control channels, so they will no longer deposit new Claremont Potatoes. However, it doesn’t appear that there will ever be a shortage of them!
Image caption: House built with Claremont Potatoes in the Russian Village District of Claremont.
To log this earthcache:
Message the cache owner with your responses to the items below. Stand on the low wall at the posted coordinates, facing north towards the larger rocks about 30 yards away.
1. Look at the Claremont Potatoes that you see stretching from here north to the larger rocks and estimate the size of the largest and smallest ones (excluding the large rocks at the end).
2. Describe the color(s) of the Claremont Potatoes and tell what type of rock you think they are.
3. Feel some of them, describe the texture (rough? smooth? jagged? rounded?), and tell how you think they got this way.
4. About how many Claremont Potatoes would you say are in this 8-foot wide / 30-yard long stretch, from where you’re standing to the larger rocks at the end? (Can you imagine digging up all of these in your yard when you were trying to build a house or plant an orange tree?)
Optional activities:
a) Take a photo of yourself with one or more Claremont Potatoes and post it to your log! (No spoilers.)
b) Visit WP2 and take a walk through the Russian Village District to see several houses and other structures built from Claremont Potatoes in the 1920s and 1930s.
Sources:
Bidwell Museum
Bernard Field Station Geography
Claremont Courier
Wikipedia
Los Angeles Times
Daily Bulletin