“A yardang is a streamlined hill carved from bedrock or any consolidated or semiconsolidated material by the dual action of wind abrasion, dust and sand, and deflation. Yardangs are elongate features typically three or more times longer than they are wide, and when viewed from above, resemble the hull of a boat. Facing the wind is a steep, blunt face that gradually gets lower and narrower toward the lee end. Yardangs are formed by wind erosion, typically of an originally flat surface formed from areas of harder and softer material. The soft material is eroded and removed by the wind, and the harder material remains.”
3. Endogamy. The Wiktionary says endogamy is: “The practice of marrying or requiring to marry within one’s own ethnic, religious, or social group.” The article has more. Didn’t know there was a name for this.
4. Factor analysis (somewhat study/exam-related).
5. History of paper.
“Toilet paper was used in China by at least the 6th century CE.” I had no idea it’s been around for that long! Also:
“The earliest recorded use of paper for packaging dates back to 1035, when a Persian traveler visiting markets in Cairo noted that vegetables, spices and hardware were wrapped in paper for the customers after they were sold.“
Latest xkcd-strip which I thought I ought to add here:
Btw, I think Randall Munroe perhaps does not spend much time around people with average IQ’s, if the RHS is supposed to illustrate that 30 point drop. The average IQ of people who don’t know what a car is, well, it’s pretty damn low (most of them also probably can neither read nor write). The learned helplessness (‘why should I remember this when I can just look it up’) aspect of tech is important, but that comic was too much over the top to do it for me.
Incidentally, the drop (which is real and significant for me too) is part of why I almost prefer to interact with people online rather than in person. I have the impression that real-time face-to-face interaction is not exactly where I have my comparative advantage. Online interaction also makes discussions with a significant knowledge-component much easier to engage in, and the lag/delay between idea exchanges which is often a part of that interaction makes sure people like me, who perhaps aren’t really all that quick on the uptake, have time to think things more through. It goes both for ‘pure ideas’ and it goes for implicit social rules and norms which I sometimes have a hard time remembering implementing when doing the face-to-face stuff because there’s not enough time to both have the conversation and be aware of all that other stuff.