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The Straight Dope

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Where do pigeons go to die? I've only seen maybe two dead pigeons in my life. Considering how many there are, the streets should be littered with them. Is there a pigeon graveyard? --Ken Ellyson, Dallas; similarly from Bobbie Warshau, Evanston, Illinois; Betty Pryde, Novato, California

What is this? Just a few years ago everybody wanted to know where the baby pigeons were; now all I get is letters asking what's become of the dead ones. This surely tells us something about where the country is headed, but Lord knows what.

You don't see many dead city pigeons for a couple of reasons. The first is that scavengers make pretty quick work of them. Insects alone can reduce a deceased pigeon to a heap of feathers and bones in a week or two. Rats, dogs, or other animals may drag the carcass off into some secret corner for a late snack. Sanitation crews scoop up a few. And of course many cities have chains of pigeon funeral homes, offering the finest in avian undertaking.

The other reason you don't see dead pigeons is that old and feeble ones usually hole up in some out-of-the-way place so they won't be seen by predators. Nooks and crannies in and around buildings are always popular, but I'd say the pigeons' favorite spot is the ironwork underneath highway and railroad viaducts. I personally inspected several and found the surrounding area littered with decaying remains. Naturally, I paused for a moment of respectful silence. I may be a hard-bitten reporter, but hey, I got my sentimental side.

FROM THE TEEMING MILLIONS

In reference to the question of why the sea is salty [April 1], I couldn't help but cringe at your explanation. Sir Edmond Halley's hypothesis, which you called the "last word" on the subject, was that salt is carried into the ocean by rivers. The latest word--I wouldn't presume to call it the last--is that salt comes from two entirely different chemical reactions that take place on the ocean floor. Salt is composed of two elements, sodium and chlorine. Sodium is weathered from feldspars and other sodium-bearing minerals in the ocean crust. A significant amount also comes from the weathering of continental granite. Chlorine, however, is exclusively volcanic in origin. It is ejected as a gas from the mid-ocean ridge and other volcanic fissures and vents on the ocean floor. The two chemicals combine in solution to form salt. The salt contributed to the ocean by rivers is actually a recirculation of existing ocean salt carried to land by processes too complicated to describe here. --Benjamin Castellana, Dallas

Not so fast, pal. You're right that most ocean chlorine is the result of "outgassing" from the earth's interior and that sodium comes from weathering. The question is where the weathering occurs. One school of thought holds that sodium leached into the water from the ocean floor at the time the seas were first created. In other words, the sea is salty because it's always been salty. However, many scientists still contend that much if not most of the sodium entered the sea by way of rivers, having first been eroded from the land by rain. In this view, the sea became saltier over time. That's basically what Halley believed, and there are few who would say he was flat out wrong. We just aren't real sure what happened back in those early days.

Where Halley was wrong was in his assumption that the saltiness of the oceans is still increasing today. We now know that ocean salinity has been constant for hundreds of millions of years as a result of a complicated mineral recycling process. Today, and arguably in the distant past as well, sodium isn't being leached out of the ocean floor, it's being put back into the floor as sediment. From there, some speculate, the mighty forces of plate tectonics shove it under the continents and eventually it winds up on the land's surface, where the weathering starts the process all over again. But much still remains to be learned.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.

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