Lightning in the Sand
As my friend Anna and I walked the sand dunes of southeastern New Mexico, she told me that she hoped we’d find a fulgurite, one as translucent white as the southeastern New Mexico sands around us. (31) A fulgurite—whose name stems from the Latin word fulgur, which means “thunderbolt”—is a hollow silica glass tube formed when lightning strikes sand. A fulgurite is created in one explosive second by fusion and pressure as sand heated by a lightning blast melts, (32) and becomes glass. Commonly called “petrified lightning,” a fulgurite places (33) the shape of a miniature lightning bolt into the earth, often branching deep into the ground.
Anna told me that I had possibly seen a small fragment of a fulgurite before, without realizing I had, on a beach. She explained though that even experts (34) are rarely able to locate a fully intact fulgurite. The thin, brittle glass tubes break easily. (35) Occasionally, after strong, sustained winds have shifted desert sands, while (36) an unbroken, previously buried fulgurite will be revealed, showing as a tube protruding from the ground. (37) I scanned the area, hopeful that I’d see a tube newly uncovered. (38) Anna made clear that we’d be lucky to come upon a small piece of fulgurite, just a few inches long. Anna had shown me fulgurites she had found on other trips. Their colors ranged from black to brown to green, corresponding to the color of the sand in which she had discovered them. I wasn’t surprised that I’d never recognized fulgurites on any beach: no one had ever told me what to look for. (39) Their interiors, though, are smooth, clear glass stained (40) with tiny bubbles trapped formed by air and moisture (41) during the rapid cooling of the melted sand after the lightning strike.
We continued exploring the dunes. Anna laughed and said we needed only to stop at the local gift shop to unearth (42) our treasure. (43) But given our (44) luck finding fulgurites in deserts and on beaches, (45) she wanted to keep searching to find our own piece of bright, white lightning in the sand.
40. Which choice makes clearest the light, sporadic arrangement of the bubbles in the glass?
A. NO CHANGE