One Daily Parker reader sent me this clarification that the big hole in CA-92 preventing people in Half Moon Bay, Calif., from reaching Silicon Valley is not, technically, a sink hole:
The first thing to know about that sinkhole that opened on Highway 92 on Thursday: It’s not a sinkhole:
Geologists make a distinction between sinkholes, which require a particular blend of soils — limestone, salts, gypsum and other components — and caverns that appear with water due to engineering failures, aging infrastructure or simply not building enough capacity to handle the kind of runoff experienced in San Mateo County this month. They also note it’s a distinction without a difference for anyone stuck in traffic.
“Even scientists can’t always agree whether we want to call them sinkholes,” said Randy Orndorf, a research geologist for the USGS in Reston, Va., who is known as the sinkhole expert within the service. “I think about 20 years ago when I started doing research, we tried to say these are infrastructure failures and people still wanted to call them sinkholes.”
For the most part, sinkholes are limited to regions of karst terrain, which underpin about 25 percent of the United States land mass. Sinkholes are most common in these areas, where the underlying soil simply dissolves in water. Sinkholes are most common in Florida, Alabama, Missouri, Kentucky, Texas, Tennessee and Pennsylvania, according to the USGS. No one knows how many sinkholes develop in a given year because most likely occur in remote areas.
(The photo caption really summarizes things well: "Geologists say this isn't a sinkhole, but they acknowledge it doesn't really matter what you call it.")
Thanks for filling us in, USGS. (Actually, I love this kind of journalism. What can you say about rain in California? Let's dig into the issue! [Sorry.])
And every time I think about sinking, I sink of this: