T HE granite rocks with rounded corners that sit on Holiday Hill year after year seem like idle things. They have a settled look as if they had been there always and would stay forever.
That giant stone, the biggest one of them all—what has it ever done? On a hot summer day, it casts a shadow where children can play comfortably or where they can sit and read without the glare of sunshine in their eyes. On blustery days, the wind breaks against the rock, leaving a quiet place on one side of it.
Perhaps you may think that is enough for a great rock to do, to make a pleasant shelter from sun and wind. What else, indeed, can it ever have done than just sit still? You will feel better acquainted with Holiday Hill itself, I think, if you know something about that huge piece of granite which looks so steadfast and unchangeable.
For the old boulder has a story of its own quite as marvelous as the tale of anything else on the hill. And in spite of the rock's quiet way of sitting there, its story is one of travel and adventure and mystery.
The mystery was a matter that kept many wise men guessing for many years.
Granite rocks with rounded corners
Vast numbers of such boulders, large and small, may be found in different places all over the northeastern part of North America. And wherever they are, there are reasons to think that they have been brought from somewhere else.
For such boulders are quite likely to be some kind of rock that is different from the solid bedrock that lies under the soil in which the boulders rest. In many places the bedrock is limestone and yet the boulders, big and little, may be granite like those of Holiday Hill.
Although they are different from the bedrock of their locality, they are like the bedrock in some other region, often far away. Certain granite boulders are like the granite mountain tops a hundred miles or more distant.
Indeed, the boulders and the mountains are so much alike that men who studied them came to think that the boulders had been broken off the mountains and scattered about the country for many miles.
The shape of the boulders puzzled people, too. They are so much like huge pebbles with their rounded sides and ends.
Of course it is easy to understand why pebbles which are touched by moving water are without sharp corners. If they are on the seashore the waves splash over them and rub them together until they become smoother and smoother. And if the little stones are in the bed of a river they are pushed against one another by the swift water currents and their rough edges are rubbed down.
But how had the great heavy rocks, in the soil or on top of it, come to be similar in shape to the little stones in rivers and on the seashore? How had their corners been worn off?
The longer people studied boulders, the more they came to believe that the large rocks had their blunt edges, as the pebbles had, by being pushed against some hard objects. It was because they thought these big stones had been knocked or rolled or bowled from one place to another that they gave them the name of boulders.
You can see what a mystery this was. What could have broken the rocky tops of mountains? What could have carried the broken pieces of rock about the country and dropped them here and there?
At last a man found an answer to these questions. His name was Louis Agassiz. In another country he had seen some high rocky mountains that were covered by enormous, deep masses of ice and snow. He knew what happened when great bodies of ice, called glaciers, pushed slowly down the mountains.
Louis Agassiz knew, too, what such a glacier did while it moved. It broke off parts of the rocks beneath it. The rocks became embedded in the ice and were carried with it. A glacier was like a solid river of ice, hundreds of feet deep, pushing rocks and soil as it went slowly on its way. And as the ice melted, of course the embedded stones dropped to the ground beneath.
A glacier is a slow‑moving river of ice
It seemed to Louis Agassiz that the boulders and much of the soil in the northeastern part of North America looked like boulders and soil that had been carried by glaciers and dropped as the ice melted.
So he believed that once, long, long ago, the mountains in this part of our country were covered with enormous weights of ice and snow. He reasoned that glaciers from these must have pushed across the land, grinding off the hilltops, broadening the valleys and shoving rocks and soil from place to place. Then, finally, as the ice melted, the boulders were left wherever they chanced to drop.
The more men thought about what Louis Agassiz told them of the movements of glaciers, the more reasonable his answer to the boulder mystery seemed. And now you may find in certain books, accounts of how the travel-worn boulders were carried by moving ice.
So we understand that the ancient stone on Holiday Hill is one of many that came from some far mountain. After a long and remarkable journey, it was left there a stranger.
But the boulder is not a stranger, now. It has sat on the same hillside for no one knows how many hundreds of years, and it seems quite at home there.
Though its travels were over long ago, its adventures were not, for changes came to the old boulder of Holiday Hill from year to year.
Air and moisture acted upon the surface of the rock, season by season, crumbling bits of it somewhat as iron is rusted when left outdoors.
Rain and snow fell upon the stone and settled in its hollows. When the water froze in winter, the rock was cracked in places.
Dust and brown dry leaves were blown upon the boulder. Some of these were later washed into the cracks by rain and formed tiny beds of soil.
Seeds, brought by wind or birds or squirrels, fell on this soil and grew. The roots of the plants reached into the cracks and pushed as far as they could into the crumbled spots.
Fires swept over that part of the hill, burning dry leaves and woody stems and tree trunks and leaving ashes and charcoal near the boulder and blackening its sides with smoke. Perhaps lightning had started some of the fires. Perhaps others had spread from Indian camps.
Plants grew on the hillside that had been cleared by fires. They scattered their seeds and spread their roots until in time the black ground was hidden under green leaves.
There were other plants of a quite different sort touching the boulder. They spread like a mat over the rock and covered much of its surface. These were the greenish gray lichens that lay with their flat parts so close against the rock that it was hard to tell where lichen left off and stone began.
Lichens had been living on Holiday Boulder ever since some tiny spores from lichens on other rocks had floated through the air and settled on this one.
The spores were finer than dust you can see in the air, but they were not too small to hold life. Young lichens grew from them, as some other plants start from seeds. The lichens had acid in them that softened the surface in which they grew. So they were able to get a firmer and firmer hold on the particles of rock to which they clung. They gave the rounded sides of the great stone a soft and lovely color.
One plant grew from a crevice in the very top of the boulder. It was a very large plant to be growing out of so narrow a crack. It was, indeed, a pine tree nearly twenty feet tall, and it was old enough to have cones with seeds.
Lichens covered the sides of Holiday Boulder and a pine tree grew in a crack at its top
Had that pine tree sprouted from a seed that had been blown to the top of the boulder years ago? Or had a bird perched there and dropped it? Or had a squirrel chosen that crack for a pantry and filled it with pine seeds, one of which had sprouted and grown?
You may ask that old giant rock as many questions as you like. But Holiday Boulder will be silent. It has no memory of any pine seed that was placed in its crevice. It does not feel the roots of the tree that are even now crowding against the sides of the crack. It does not know that blueberry bushes are brushing its surface with their branches and pushing their stems through its crumbling granite base. It does not feel the touch of the acid lichens or sense the difference between fire and frost.
Yes, you may question that ancient stone; but it has no knowledge of any of the events in all the marvelous story of its existence. Not even of that strange and icy journey that took place during those years before it came to sit on Holiday Hill!