The Western United States Part 5

Near La.s.sen Peak, the southernmost of the great volcanoes of the Cascade Range, there lies another field of recent volcanic activity of even greater interest than the first. The centre of attraction is Cinder Cone, similar to Shadow Mountain in its manner of formation as well as in materials, but more symmetrical in form. Upon one side is a field of black lava several miles in extent, while volcanic sand has been spread over all the adjacent country.

[Ill.u.s.tration: FIG. 27.--THE CRATER OF CINDER CONE]

As nearly as can be determined, only a little more than two hundred years ago the valley now occupied by Cinder Cone and the lava fields gave no indication of ever becoming a new centre of volcanic action.

It has been thousands of years since the ancient volcanic peaks and cinder cones of this mountainous region became extinct. The glaciers had come, and torn and ground away the surface of the lava, and afterward dense forests had hidden all the rocky slopes, while lakes had occupied many of the valleys. Far below, however, the fires had not gone out. In many places there were boiling springs from which the steam, upon cold mornings, rose in dense white clouds.

Then, for some reason which we do not understand, the forces beneath the surface increased their activity. The force of the steam and other gases was too great to be restrained, and at a weak spot in the overlying rocks they broke through. Molten lava accompanied them, and a new volcano came into life in the valley where Cinder Cone now raises its dark, symmetrical slopes.

The eruptions were violent. With explosive force the molten lava was torn into fragments, and sand, lapilli, and bombs were hurled out into the air. The finer particles were carried by the air currents far over the surrounding country. The lapilli, scoriae, and bombs fell around the throat of the volcano, finally building up the cone to its present proportions. The great bombs, some of them five feet in diameter, are among the most remarkable products of this eruption. They lie scattered about upon the surface of the ground at the foot of the cone, and, although they are often irregular in shape, they might almost be mistaken for huge cannon-b.a.l.l.s.

The eruption killed and burned the trees in the near-by forests, burying them under six or seven feet of fine sand or ashes. After the cone had been built and the explosive eruptions had nearly stopped, a stream of molten lava burst from the base of the cone and filled a portion of the valley.

Now followed a long period of quiet. Trees began to grow upon the sand and gradually to encroach upon the barren wastes about Cinder Cone. It appeared as if there were to be no more eruptions. But the volcano was only resting. At about the time, perhaps, when the gold seekers began to pour across the continent to California, there was another eruption; but this time it took the form of a lava flow and was so quiet as to create no disturbance in the surrounding country.

[Ill.u.s.tration: FIG. 28.--CINDER CONE

The trees were killed by the last eruption of volcanic ashes]

A stream of thick, viscous lava flowed slowly out of an opening at the southern base of Cinder Cone. As the lava crept down the gentle slopes of the valley, it crusted over, forming a black, slag-like surface. The surface was from time to time broken up and mixed with the softer portions beneath, so that the movement of the flow was still further r.e.t.a.r.ded. At the lower end of the valley the lava occupied a portion of a body of water now known as Lake Bidwell; its rugged front made a dam across the valley above, forming Snag Lake. The stumps of the trees which were killed by the water when the lake was first formed are still standing.

[Ill.u.s.tration: FIG. 29.--THE LAST LAVA FLOW IN THE UNITED STATES

At Cinder Cone, California. It formed a dam across a valley, thus creating Snag Lake]

One's feet sink deep into volcanic sands, and walking is tiresome.

The lava field resulting from the last eruption is free from sand, but its rough surface, formed of broken blocks, is difficult to cross.

A few charred stumps rise out of the sand, pathetic remnants of the forest trees that were growing at the time of the first eruption.

Most of the trees have completely disappeared, leaving shallow pits where they once stood.

It is exceedingly difficult to climb the cone, which rises over six hundred feet, for the slopes, composed of loose lapilli, are so steep that one slips back at every step nearly as far as he advances. From the summit a remarkable sight meets the eye. Within the rim of the main crater is a second crater with a rim nearly as high as the first, while the cavity within has a depth of about two hundred and fifty feet.

Because of the loose character of the material of which it is built, no streamlets have yet worn channels down the slopes of Cinder Cone, and except for the presence of two small bushes which cling to its side, it is just as bare and perfect in form as when first completed.

Little by little the forests are encroaching upon the sand-covered slopes about the cone, and in time these slopes, the black fields of lava, and the cone itself, will be covered with forests like the older lava fields and cinder cones which appear upon every hand.

THE MUD VOLCANOES OF THE COLORADO DESERT

The Colorado Desert is a strange, weird region. Here is a vast basin at the head of the Gulf of California which was once a part of the gulf, but is now separated from it by the delta of the Colorado River. With the drying up of the water, the centre of the basin was left a salt marsh more than two hundred and fifty feet below the level of the ocean. In summer the air quivers under the blazing sun, and it seems as if no form of life could withstand the scorching heat, but in winter the atmosphere is cool and full of life-giving energy.

Around this desert rise the mountains, some old and nearly worn down, their tops barely rising out of the long slopes of sand and gravel; others rugged and steep, lifting their crests far above the burning desert into the cold, clear sky.

Curious forms of plants and animals find their homes upon the slopes about the basin, where they adapt themselves to the heat and dryness.

But toward the centre the soil is bare clay, for when the water dried up so much alkali and salt were left that nothing could grow.

However we do not now intend to study the plants or the animals, interesting though they are, but rather a group of mud volcanoes, which forms almost the only relief in the monotony of the bare plain. These volcanoes are in no way related to real volcanoes except in shape, for water and mud, instead of fire and lava, have been concerned in their building.

[Ill.u.s.tration: FIG. 30.--MUD VOLCANOES, COLORADO DESERT]

Once it required a long journey in wagons or upon horseback to reach the mud volcanoes, but now the railroad takes us within three miles of the spot. We alight from the train before a section house which stands in the midst of the great desert. Far, far away stretches the barren clay floor of the ancient lake. Here and there are scattered stunted shrubs, the only specimens of plant life which have been able to withstand the alkali in the clay.

Seen from the station, the volcanoes appear like dark specks almost upon the horizon, but in reality they are not far away, and an hour's brisk walk will bring us to them. The mud springs, which are scattered over an area of several hundred acres, present many strange and interesting features. There are holes in the earth with bubbling mud at the bottom, cones from the tops of which streams of muddy water issue, and ponds of mud, in some cases as thick as mola.s.ses, in others thin and watery. There are little jets of steam, strange odors, and a vista of many mingled colors. Taken altogether, it is a place quite different from any other that we have ever seen.

The ground is soft and marshy, and in some places undermined by the water, so that we have to take great care in walking about.

Some of the smaller springs occupy round depressions, sometimes three or four feet across, which look as if they had been made by pressing a large pan down into the clay. The bubbling mud in the bottom of the pan, as well as the hot water in many of the springs, makes it easy to imagine that we are standing upon the top of a great cooking stove in which a hot fire is burning. As the gas with which the water is impregnated comes up through the mud, it forms huge bubbles which finally break and settle down, only to rise again. In this way concentric mud rings, perfect in form, are made to cover the entire surface of the pool.

Where there is little water, the surface of the mud hardens and leaves a small opening, through which the bubbling gas throws small columns of mud at regular intervals. From the large pools, some of which are forty to fifty feet in diameter, there comes a low murmuring sound like the boiling of many kettles. The water is sputtering and bubbling, and in some places it is hot enough to give off thin clouds of steam. Occasionally we get whiffs of sulphur, while about the borders of some of the ponds pretty crystals of this mineral can be found.

More commonly the pools are crusted about with a white deposit of salt, for they all contain more or less of this substance in solution. Around a few of the pools the mud is stained with the red tinge of iron, and red lines mark the paths of the streams as they run off from the pools toward the still lower portions of the desert.

[Ill.u.s.tration: FIG. 31.--POT-HOLES]

The built-up cones or volcanoes appear in every stage, from the little ones a few inches high to the patriarchs, which in some cases have reached a height of twelve feet. These cones are formed by the hardening and piling up of mud about the openings; but when they have reached the height mentioned, the pa.s.sages up through their centres, corresponding in each case to the throat of a real volcano, become clogged and new holes are formed in the mud at the base.

[Ill.u.s.tration: FIG. 32.--AN EXTINCT MUD VOLCANO

With small active one at its side]

Many of these mud volcanoes closely resemble true volcanoes in form and structure. The mud which pours out at the top forms streams down the slopes very like those of molten lava. New cones are built upon the sides or at the bases of the old ones in much the same way as are those in the volcanic regions.

There are no signs of volcanic action in the vicinity of these mud springs, and it is likely that the water is forced to the surface by large quant.i.ties of gas produced by chemical changes taking place deep within the clay beds of the old lake. Similar springs occur farther south, nearer the mouth of the Colorado River, in the Yellowstone Park, and near La.s.sen Peak, but nowhere in America except in the Colorado desert have they formed such large and interesting mounds.

THE HISTORY OF A COAST LINE

The story of our Pacific coast reads more like a tale from the "Arabian Nights" than like a plain statement of events which have actually happened.

The meeting place of the land and ocean is not really so permanent a line as it appears. The sh.o.r.e has been continually moving back and forth throughout the long history of the earth. That which was dry land at one time was at another time deeply buried beneath the ocean. The Pacific border seems never to have been at rest. It has risen and sunk again repeatedly. It has been squeezed, folded, and broken, shaken by earthquakes, and disturbed by volcanic eruptions.

One might be led to think from this statement that it would not be safe to live on the Pacific coast, and that both animals and men would shun the region. The fact is, however, that these changes usually come to pa.s.s so very slowly that we are not aware of them.

Severe earthquakes and volcanic disturbances take place so rarely in comparison with the length of a man's life, that we may pa.s.s our whole lives without experiencing any of these violent disturbances.

The Pacific coast region, with its forest-covered mountains, fertile valleys, and beautiful homes, presents so quiet and peaceful an appearance that it is difficult to believe that parts of its history have been so tumultuous.

Perhaps you will ask how we can know so much about the past. It is true that no one was here to witness the events which are supposed to have taken place. But Nature has left a record of her doings which we have only to see and understand in order to learn with certainty many things which happened in the far distant past.

Too many of us go through life seeing and understanding almost as little of the world about us as if we were blind. Our early ancestors were obliged to understand many things about Nature and to cultivate clear and close observation for the sake of self-preservation. The very life of the savage depends upon the training of his eyes. He must be able to tell the meaning of a distant object or an indistinct trail, for his enemies may have pa.s.sed that way recently. If we could bring the sharp eyes of the savage to our aid, the world would mean much more to us.

In order to learn something of the history of the Pacific sh.o.r.e line, we must see what the waves are doing at the present time.

The projecting points of land are being worn away (Fig. 33). The waves form the cliffs against which they beat, and sometimes, as they eat their way slowly into the land, they cut off portions and leave them standing alone as islands.

The pebbles and boulders (Fig. 34) were once angular fragments torn from the cliff. They have been washed about and hurled against the solid rock until they have been worn smooth; and the cliff in turn has had a cave ground out at its base. Above the lower cave there is a remnant of a second one, with pebbles upon its floor. This was made when the land stood ten feet lower than at present.

As the waves wear away the loose earth and the solid rock below it, moving the cliffs inland, they leave a comparatively smooth surface which is partly exposed at low tide. The fact that this surface is not marked by stream channels, as is the land, helps us to realize the great difference between the irregular surface of the latter and the plain-like character of the ocean floor.

[Ill.u.s.tration: FIG. 33.--POINT BUCHON, CALIFORNIA