ABOUT A BILLION YEARS AGO, LONG BEFORE THE CONTINENTS had separated to define the ancient oceans, or their own outlines had been determined, a small protuberance jutted out from the northwest corner of what would later become North America. It showed no lofty mountains or stern shorelines, but it was firmly rooted in solid rock and would remain permanently attached to primordial North America. Its position, fixed though it was in relation to the larger landmass, did not long remain at what seemed the northwest corner, because, as we know from studies which flowered in the middle years of this century, the surface features of the earth rest on massive subterranean plates which move restlessly about, sometimes taking this position or that and often colliding with one another. In these ancient times the future North America wandered and revolved at a lively rate; sometimes the protuberance lay to the east, or to the north or, more dramatically, the far south. During one long spell it served as the temporary North Pole of the entire earth. But later it stood near the equator and then had a tropical climate. It was, in effect, a fixed attachment to a wildly vagrant landmass, but it bore continuing relation to other would-be continents like Europe or, more significantly, to the Asia with which it would intimately be associated. However, if one had followed the errant behavior of this small jutting of rocky land attached to the larger body, one could never have predicted its present position. The destiny of this persistent fragment would be to form the rootstock of the future Alaska, but during this early formative period and for long thereafter, it remained only that: the ancestral nucleus to which the later and more important parts of Alaska would be joined. During one of the endless twists and turns, about half a billion years ago, the nucleus rested temporarily about where Alaska does today, that is, not far from the North Pole, and it would be instructive to visualize it as it then was. The land, in a period of subsidence after eons of violent uprising, lay not far above the surface of the surrounding seas, which had even yet not separated themselves into the oceans we know. No vast mountains broke the low profile, and since trees and ferns had not yet developed, Alaska, which amounted only to a minor promontory, was unwooded. In winter, even at these high latitudes, a phenomenon which would always characterize northern Alaska pertained: it did not receive much snow. The surrounding seas, often frozen, brought in so little precipitation that the great blizzards which swept other parts of the then world did not eventuate, and what little snow did fall was driven here and there by howling winds which swept the earth clear in many parts or left it lightly drifted in others. Then as now, the winter night was protracted. For six months the sun appeared low in the sky, if it appeared at all, while the blazing heat of summer came in a season of equal length when the sun set only briefly. The range of temperature, under a sky which contained less relative moisture than now, was incredible: from 120° Fahrenheit in summer to the same number of degrees below zero in winter. As a consequence, such plants as tried to grow--and there were none that resembled anything with which we are now familiar--had to accommodate to these wild fluctuations: prehistoric mosses, low shrubs with deep roots, little superstructure and almost no leaves, and ferns which had adapted to the cold clung to the thin earth, their roots often thrusting their way down through crevices in rock. No animals that we would recognize as such roamed this area, for the great dinosaurs were still far in the future, while the mastodons and mammoths which would at one time dominate these parts would not begin even their preliminary genesis for many millennia. But recognizable life had started, and in the southern half of the little promontory tentative forms moved in from the sea to experiment on land. In these remote and formless days little Alaska hung in suspense, uncertain as to where its mother continent would wander next, or what its climate would be, or what its destiny. It was a potential, nothing more. It could become a multitude of different things; it could switch its attachment to any of three different continents; and when it enlarged upon its ancestral nucleus it would be able to construct miraculous possibilities. It would lift up great mountains, the highest in North America. It would accumulate vast glaciers, none superior in the world. It would house, for some generations before the arrival of man, animals of the most majestic quality. And when it finally played host to wandering human beings coming in from Asia or elsewhere, it would provide residence for some of the most exciting people this earth has known: the Athapascans, the Tlingits and much later the Eskimos and Aleuts. But the immediate task is to understand how this trivial ancestral nucleus could aggregate to itself the many additional segments of rocky land which would ultimately unite to comprise the Alaska we know. Like a spider waiting to grab any passing fly, the nucleus remained passive but did accept any passing terranes--those unified agglomerations of rock considerable in size and adventurous in motion--that wandered within reach. Where did these disparate terranes originate? How could blocks so massive move about? If they did move, what carried them north toward Alaska? And how did they behave when they bumped into the ancestral nucleus and its outriders? The explanation is a narrative of almost delicate intricacy, so wonderfully do the various terranes move about, but it is also one of cataclysmic violence when the terranes finally collide with something fixed. This part of Alaska's history is one of the most instructive offered by earth. The visible features of the earth, including its oceans, rest on some six or eight major identifiable subterranean plates--Asia is one, obviously; Australia another--plus a score of smaller plates, each clearly defined, and upon their slow, almost imperceptible movement depends where and how the continents and the oceans shall sit in relation each to the other. At what speed might a plate move? The present distance from California to Tokyo is 5,149 miles. If the North American plate were to move relentlessly toward Japan at the infinitesimal rate of one-half inch per year, San Francisco would bump into Tokyo in only six hundred and fifty million years. If the plate movement were a foot a year, the transit could be made in about twenty-seven million years, which is not long in geologic time. So the movement of a terrane from anywhere in Asia, the Pacific Ocean or North America to the growing shoreline of Alaska presented no insuperable difficulties. Given enough time and enough movement of the respective plates, anything could happen ... and did. In one of the far wastes of the South Pacific Ocean a long-vanished island-studded landmass of some magnitude arose, now given the name Wrangellia, and had it stayed put, it might have produced another assembly of islands like the Tahiti group or the Samoan. Instead, for reasons not known, it fragmented, and its two halves moved with a part of the Pacific Plate in a northerly direction, with the eastern half ending up along the Snake River in Idaho and the western as a part of the Alaskan peninsula. We can make this statement with certainty because scientists have compared the structure of the two segments in minute detail, and one layer after another of the terrane which landed in Idaho matches perfectly the one which wandered to Alaska. The layers of rock were laid down at the same time, in the same sequence and with the same relative thickness and magnetic orientation. The fit is absolute, and is verified by many matching strata. Through the millennia similar wandering terranes seem to have attached themselves to the Alaskan nucleus. Frequently some enormous slab of rocky earth--sometimes as big as Kentucky--would creep relentlessly north from somewhere and bang into what was already there. There would be a rending of the edges of the two terranes, a sudden uprising of mountains, a revolution in the existing landscape, and Alaska would be enlarged by a significant percentage. Sometimes two smaller terranes would collide far distant from Alaska; they would merge and for eons would form an island somewhere in the Pacific, and then their plate would imperceptibly move them toward Alaska, and one day they would touch Alaska, so gently that even the birds inhabiting the island would not know that contact had been made, but the onetime island would keep remorselessly encroaching, grinding down opposition, overwhelming the existing shoreline of Alaska or being overwhelmed by it, and no casual observer would be able to detect where or how the join of this new land to the old had been accomplished. Now, obviously, after eight or ten such terranes had pushed against the ancestral nucleus, none of its original structure still touched the ocean, for it had been surrounded on all exposed sides by the incoming lands. A great peninsula, one of the largest on earth, was in the process of being formed, an immense proboscis reaching out toward Asia, which was also in the process of its formation. About seventy million years ago this nascent peninsula began to assume a shape vaguely like present-day Alaska, but shortly thereafter it acquired a peculiarity with which we today would not be familiar. Excerpted from Alaska by James A. Michener All rights reserved by the original copyright owners. Excerpts are provided for display purposes only and may not be reproduced, reprinted or distributed without the written permission of the publisher.
