Os Estados Unidos (estrictamente falando, o CONUS) pódense dividir de moitas maneiras, por exemplo:

• Estados do Norte e Estados Sureños (os ecos da Guerra Civil inda se escoitan forte, especialmente ao sur da liña Mason-Dixon).
• Conferencias Leste e Oeste das grandes competicións deportivas (só da NBA e da NHL, que os do fútbol americano e o béisbol son moi seus ata para eso).
• As rexións administrativas do United States Census Bureau: Noreste, Sur, Medio-oeste, e Oeste.
• Por usos horarios (Pacífico, Montañas, Central e Atlántico).

Todas estas son divisións artificiais do territorio (como as propias fronteiras, por outra parte). Pero podemos escoller outro xeito de dividir grandes territorios continentais, baseado na propia xeografía do terreo: trazando as divisorias de drenaxe, a liña que separaría dúas concas hidrográficas contiguas. E, escollendo río a río e regato a regato coidadosamente, separando aqueles que verten a un ou outro mar ou océano, conseguiremos dividir elegantemente todo un continente. E, xa que os “Contiguous 48” están convintemente encaixonados entre o Atlántico e o Pacífico, resulta moi cómodo empregar este método para dividilos en dúas metades, a vertente atlántica e a pacífica, mediante unha liña que segue os puntos máis altos das Montañas Rocosas.

Pois ben, esta división xeográfica tampouco é correcta ao 100%. Sendo meticulosos, atoparemos irregularidades na liña, como concas endorreicas que se atravesan no percorrido da divisoria, por exemplo a Great Divide Basin, situada no Red Desert, en Wyoming.

Non son estas as particularidades das que vos quero falar hoxe. Quérovos contar a historia de dúas gotas de auga. As dúas formaban parte do mesmo floco de neve, e caeron no inverno nunha meseta nas montañas rocosas, ao noreste de Wyoming, no espacio natural chamado Teton Wilderness. Cando chegou a primavera, no desxeo, a zona na cal caeron foise derretendo, creando unha corrente de auga. Por esa corrente, chegado o momento, se precipitan as dúas pinguiñas, unha ao carón da outra, ata que chega o desastre: topan cunha pedra. E sepáranse, unha corre cara a dereita, a outra cara a esquerda. Nunca se volveron ver. Logo de todo un inverno xuntas, tan brusca separación foi devastadora. E as pingas choraron, e choraron. Choraron cada unha o seu río, e seguiron viaxe metidas nel ata o mar. Pero, ata cal?

O curioso é que esa pedra se atopa no punto máis alto dun porto de montaña chamado Two Ocean Pass. E o regato de desxeo que baixaba desde a meseta era o North Two Ocean Creek. Ao dividirse no porto de montaña, un dos regatos que se forma é o Atlantic Creek; e o outro, o Pacific Creek. Vedes a onde quero chegar, non?

Efectivamente, neste punto da foto, chamado apropiadamente Parting of the Waters, a auga do North Two Ocean Creek divídese entre o Atlantic Creek (cara a esquerda na foto) e o Pacific Creek (á dereita).

O Atlantic Creek é afluente do río Yellowstone, e logo de atravesado o famoso parque nacional, verte ás súas augas, primeiro ao Missouri, e finalmente ao maxestuoso Mississippi, inspirador de Mark Twain nas súas “Aventuras de Huckleberry Finn”, e de milleiros de pesadelos de escolares americanos en concursos de deletreo. O Mississippi finalmente proba a sal nas costas de Louisiana, bailando ao ritmo do jazz de Nova Orleans.

Pola outra banda, o Pacific Creek ten un percorrido máis curto, 2170 quilómetros fronte aos 5610 km que percorre o seu irmán, e menos glamouroso, pois percorre os ríos Snake e Columbia antes de coñecer o océano Pacífico no mesmo punto onde o coñeceron Lewis e Clark, en Astoria, Oregon.

Temos pois, outra posible división dos Estados Unidos tendo en conta criterios de xeografía física: atoparse a un lado ou a outro da maior vía contínua de auga doce do mundo, case 7780 km de costa a costa. De feito, considérase que este regato pode ser o camiño que empregaron os peixes para chegar ao río Yellowstone, xa que moitos outros ríos desa zona non teñen peixe, ao tratarse dunha meseta elevada onde a meirande parte dos cursos de auga forman importantes fervenzas. En palabras do Doutor Barton Warren Evermann, ictiólogo da US Fish Comission que investigou a zona en 1891:

We stood upon the bank of either fork of Atlantic Creek, just above the place of the ”parting of the waters,” and watched the stream pursue its rapid but dangerous and uncertain course along the very crest of the “Great Continental Divide.” A creek flowing along the ridgepole of a continent is unusual and strange, and well worth watching and experimenting with.

We waded to the middle of the North Fork, and, lying down upon the rocks in its bed. We drank the pure icy water that was hurrying to the Pacific, and, without rising, but by simply bending a little to the left, we took a draught from that portion of the stream which was just deciding to go east, via the Missouri-Mississippi route, to the Gulf of Mexico.

And then we tossed chips, two at a time, into the stream. Though they would strike the water within an inch or so of each other, not infrequently one would be carried by the current to the left, keeping in Atlantic Creek, while the other might be carried a little to the right and enter the branch running across the meadow to Pacific Creek; the one beginning a journey which will finally bring it to the Great Gulf, the other entering upon a long voyage in the opposite direction to Balboa’s ocean.

Pacific Creek is a stream of good size long before it enters the Pass, and its course through the meadow is in a definite channel; but not so with Atlantic Creek. The west bank of each fork is low, and the water is liable to break through anywhere, and thus send a part of its water across to Pacific Creek. It is probably true that one or two branches always connect the two creeks under ordinary conditions, and that, following heavy rains, or when the snows are melting, a much greater portion of the water of Atlantic Creek finds its way across the meadow to the other.

It is certain that there is, under ordinary circumstances, a continuous waterway through Two-Ocean Pass of such a character as to permit fishes to pass easily and readily from Snake River over to the Yellowstone, or in the opposite direction. Indeed, it is possible, barring certain falls in Snake River, for a fish so inclined to start at the mouth of the Columbia, travel up that great river to its principal tributary, the Snake, thence on through the long, tortuous course of that stream, and, under the shadows of the Grand Tetons, enter the cold waters of Pacific Creek, by which it could journey on up to the very crest of the Great Continental Divide to Two Ocean Pass; through this Pass it may have a choice of two routes to Atlantic Creek, in which the down-stream journey is begun. Soon it reaches the Yellowstone, down which it continues to Yellowstone Lake, then through the lower Yellowstone out into the turbid waters of the Missouri. For many hundred miles, it may continue down this mighty river before reaching the Father of Waters, which will finally carry it to the Gulf of Mexico—a wonderful journey of nearly six thousand miles, by far the longest possible fresh-water journey in the world.

We found trout in Pacific Creek at every point where we examined it. In Two-Ocean Pass, we obtained specimens from each of the streams, and in such positions as would have permitted them to pass easily from one side of the divide to the other. We also caught trout in Atlantic Creek below the Pass, and in the upper Yellowstone, where they were abundant.

Thus it is certain that there is no obstruction even in dry weather to prevent the passage of trout from the Snake River to Yellowstone Lake; it is quite evident that trout do pass over in this way; and it is almost absolutely certain that Yellowstone Lake was stocked with trout from the west, via Two-Ocean Pass.

 

 

Para saber máis:
· Parting of the Waters. Futility Closet.
· Plano topográfico da zona. Wikimedia.
· Parting of the Waters: a creek that flows to two oceans. US Ends.
· This Creek Divides the United States in Two. From Quarks to Quasars
· Two Ocean Pass and the Mystery of the Fishless Waters. M. Mark Miller
· Mother Nature’s Oddities: Parting of the Waters. Wyoming Tourism

 

Banda sonora do post: Bicoastal Collective: Chapters 1, 2, 3, 4 – Paul Tynan & Aaron Lington.