Everything that happens leaves a permanent impression upon both living beings and objects, whose past history may often be read as one reads the pages of a book.
To a geologist, a pebble picked up on a beach shows traces of its origin upon some mountain range, which he may even be able to identify. The first rough shaping of the angular fragment was received during its long journey to the sea. This may have taken many hundreds of years until through rolling and pounding amid the boulders of the stream bed during winter floods, the pebble became more or less ball-shaped. Once on the beach, years and centuries of flattening produced by the restless waves continually moving the pebble back and forth on the sandy shore finally reduced this ball to a flattened disk.
To a botanist a tree shows by its structure the history of its kind, for the individual in its development recapitulates the evolution of its race. Moreover the series of annual rings records the climate for every year of growth, indeed every rain leaves its imperishable writing in the wood of that year.
The history of the earth is divided into eras and periods which differ widely in climate and life. Yet a slender line of living plants and animals has continued from each period down to the present time, so that we may study the life of hundreds of millions of years ago, in what can be seen on an afternoon's walk. Each of these descendants from past ages, has received an impression from the succeeding periods through which it has lived.
Recent geological history reveals a series of alternate fluctuations in climate as the epochs of the great ice age were separated by times of general warmth. Since the decline of the ice age some 25,000 years ago, cycles of warmth and cold, rain and drought have come and gone like the successive waves of a retreating tide; each leaving traces of its passing in the flotsam of lives, colonies, and arboreal islands scattered here and there over the country.
Sometimes these examples of past ages are quite impressive. Such is the case with two of whose existence I have just learned. The first, the Desert of Maine, a 500-acre area a short distance from Freeport, Maine, is described in an interesting tourist folder. Here amid the pine forests and fertile farms of a state far removed from desert conditions, lies an area of drifting sands which is with every year seizing upon more and more of the surrounding country. Where it will end no one can tell. According to the records this desert was at one time a fertile farm, then about fifty years ago a small patch of sand appeared which has steadily increased in size to the present day. Geologists believe the area was once the bed of a desert dry lake which had become overlaid by a thin layer of top-soil. When this was washed or blown away the fine sands were exposed and began to form moving dunes, which quickly invaded the surrounding country. Small as the desert is it is remarkable for its great variety of colored sands, and, strangest of all, there is even a tiny oasis about a spring of ice-cold water.
Maine itself is said to occupy some of the oldest land in the United States, great mountains have worn down almost to the plain, and large portions of the ancient land-mass now lie beneath the Atlantic Ocean. More recently continental across the country, carving and smoothing the land to its present form.
The second example of prehistoric survival, is described in the Ford Times for February under the title of "The Misplaced Muskeg," by Burgess H. Scott.
Deep in the mountains of West Virginia lie a number of small bogs filled with a tangled growth of reindeer moss, sedge, sphagnum and lichen, characteristic of the Muskeg and Tundra over a thousand miles to the north.
It is as though a bit of northern life and atmosphere had been transplanted entire to this southern location, for even the animals and birds are of northern species. Spruce trees growing between the bogs, though in some cases a hundred years old, have only reached a height of 15 to 20 feet.
Unlike the preceding instance of a relict desert, the Muskeg Glades are isolated areas left by the great continental glaciers when they retreated at the close of the Ice Age. A period of increased warmth brings a wave of southern types far beyond their normal range. On the other hand a time of lowered temperature and increased rainfall forces boreal plants and animals far to the south. Both climates upon retreating or contracting leave colonies which may survive for thousands of years. It is thus nature preserves seeds of former vegetation in case she may need to use them again. It is more than that, it is a memory of the past preserved intact for him who chooses to read.