Maybe you know someone who would love a full-size pewter replica of a USGS benchmark. Or that proverbial big sphinx of quartz that my jackdaws love—or at least a big quartz sphere. Here's a list of geologic gift ideas to help you come up with such things.

I was out this morning scouting some sites for a field trip related to ophiolites. Naturally it focused on those strange and unfamiliar rocks that most people never heard of: peridotite, serpentinite, greenstone, gabbro. On a whim (well, to check my tires) I visited one last roadcut and stared at the dark gray stone there, shot with carbonate veins and blocky fractures. "Are you metabasalt?" I asked it. Sometimes that helps, though not always right away. After a while I said, "No you're sandstone, aren't you." I had my eyes open for ophiolite, not sandstone. But that's what it was; specifically it was graywacke. A familiar rock, but with a strange name.
_{Graywacke — Geology Guide photo}

With the Thanksgiving holiday coming up, expect Plymouth Rock to take its regular turn in the spotlight. Supposedly the landfall of the Pilgrim colonists in 1620, the rock is rather more fragile than is suggested by its iconic character. In my discussion of the rock I note that having been carried to Plymouth Beach by the glaciers (and thus qualifying as an erratic), it was probably damaged in transit. Reader Walter Handy, who studied geology nearby, says that the beach is eroding its way through a drumlin and is littered with boulders—so let us add marine erosion to the rock's history of insults. The topographic map of Plymouth doesn't show classic tapered drumlins, just lumpy, poorly organized ground, so maybe the rock was eroded out of ground moraine. Either way, Plymouth Rock was ridden hard and put away wet, as the saying goes. Neither could the added stress of celebrity, so well documented in humans, have helped Plymouth Rock in maintaining its integrity.
_{Idealized Plymouth Rock — Geology Guide photo}

Close observers of this space may have noticed that the title of geology.about.com—the line at the very top of the browser—now includes "Earth science" as well as "geology." For many years I've insisted on the word "geology" to cover all the ground of Earth-based science. I've thought of "Earth science" as a sort of interloper, a newfangled, dumbed-down substitute. But I'm not always right. Sometimes, the rest of the world is right.

So now I'm exploring what exactly people mean by Earth science as opposed to geology. My first thought is that geology is whatever people did up to plate tectonics and Earth science encompasses the new jobs and tasks that have arisen since then. So prospecting, mapping, fossil studies, site investigation—that's geology. Water supplies, waste disposal, mine remediation, climate change—that's Earth science.

But I'd like your ideas.