A side of Washington State that I didn’t know existed before our graduate student geology field trip last month:

If you get in your car in Seattle and proceed to cross over the Cascades, you’ll probably run into this landscape – dry, desert-like, a far cry from the lush abundance of coastal Washington. The reason is clear – the rain shadow to the east of the Cascade mountain range – but I was expecting a landscape much more similar to the eastern plains of Colorado.

But I digress from the above landscape, Dry Falls, and how it relates to my book-of-the-moment, Ice Ages: Solving the Mystery by Imbrie and Imbrie. The Dry Falls are a dramatic erosive feature, a large-scale valley with nearly-vertical valley sides. How would you imagine that these were formed? If you were J. Harlen Bretz, you would hypothesize that the Falls were formed due to large-scale catastrophic flooding, and in this case, you would be right. It seems that the Dry Falls were formed when an ice dam broke ~20,000 years ago, releasing a flow of water about ten times greater than that of all the current rivers of the world combined. Hard to imagine? Indeed – and one of the reasons that Mr. Bretz had to defend his theory for much of his life against skeptical peers.

The human capacity to intuit the non-intuitive from geologic evidence has allowed for inferences such as Bretz’s. But the process seems far from strictly logical – one must be able to imagine a place that looked dramatically different from today. As I read through Ice Ages, I am struck by the great (and sometimes) entertaining variety of explanations that were made for glacial features left in the record. And while it is easy today to accept the current theories as sensical and the remainder as absurd (and often, too catastrophic), the distinction is in part due to time alone. Imbrie and Imbrie write

One inference, however, was so extravagant that it cast doubt on the theory as a whole. For Adhemar argued that the gravitational attraction of the Antarctic Ice Sheet was large enough to drain the water from the northern hemisphere ocean and create a sea-level bulge in the southern hemisphere. Painting a dramatic picture of what would happen if temperatures in the southern hemisphere began to rise, Adhemar predicted that the huge Antarctic ice cap would soften and rot until finally – eaten away at its base by the warming ocean – it would be left standing like a giant mushroom. At last, the entire mass would collapse into the sea, creating a huge iceberg-laden tidal wave that would sweep northward to engulf the land. (pp. 73-5)

Absurd? Catastrophic? Yes on both counts. But it takes a bit of the same disposition to think of the huge tidal-wave theory and the enormous flood theory. The key is having both the imagination and the ability to rein it in, given data and a bit of common sense. Just remember that there’s some chance that anything you can imagine may have happen in the earth’s past.

And finally, an interesting fact that I’d forgotten about – the Northern Hemisphere gets more sunlight hours per year than the Southern Hemisphere, thanks to its greater distance from the sun during spring and summer. (Remember Kepler’s Laws? The orbit of the earth must draw out equal area in equal time, demanding that the earth moves more slowly when it is farther from the sun.)


In praise of public libraries

I have had the great fortune of living near two wonderful libraries within the last year – the Wellington City Library during my year in New Zealand, and now the Cambridge Public Library (above, during a recent warm end-of-summer night). I began going to the Wellington library shortly after I moved to NZ in recognition of the high cost of books in the country, to say nothing of the high cost of bringing those acquired and treasured books back across the Pacific. But my love affair with the library really flourished during my final months in Wellington, when I was writing my masters’ thesis. Days of writing were much improved when I was able to spend them sitting amidst a diverse crowd of Wellingtonians, looking out over Civic Square and taking breaks walking along the nearby waterfront. At the library, I saw school children deciding to spend their holidays reading, businessmen negotiating deals with the dreaded Australians, and older women reading books on art history. I was reminded that a library does not need to be a place of work, of stress, as it often felt during the college years. Rather, those around me at the Wellington library were, by and large, there to read materials that they were interested in without needing to financially invest in the words. At the library (when I probably should have been writing said thesis), I re-discovered my love for the New Yorker and its in-depth discussions of topics that are both random and apt, and my time there morphed from laptop-bound hours of writing to weekend afternoons of pleasure reading.

I’ve already mined the Cambridge Public Library for their New Yorkers, although I subsequently decided to split a subscription with a friend and so will no longer need to find it on the shelves. The next forgotten or undiscovered treasure can’t be too far away, though. I intend to continue my library patronage, despite the resources in Harvard’s own libraries, to remind me that the pursuit of knowledge is not one that should be wound up in the stresses of the Ivory Tower. Rather, I’ll sit among a community of which only a small minority will be studying for their qualifying exams, that spans ages and careers and interests, and with whom I might have to fight over the last copy of Harper’s.