[Geysers] ID of picture on NPS site

[Michael Goldberg]

Hi everyone,

I just noticed a couple of links on the NPS Webcam page to a collection of 
short videos detailing various aspects of the park.  One of them, called
"How Do You Tell a Geyser from a Hot Spring?" has a cover picture that's 
giving me trouble.  The image is at the site

http://www.nps.gov/archive/yell/insideyellowstone/images/How-to-tell-GeyserHot-Sp.jpg

Or you can find it by navigating the "Inside Yellowstone" link and 
clicking on the Old Faithful area.

My gut feeling says this should be something obvious (e.g. Rocket), but
I can't seem to pin it down.  Your help identifying this feature is 
appreciated.

Michael Goldberg
mikeg at math.jhu.edu