The trail up the slope of the miniature volcano leads across this flow which is around the entire southwestern edge of the island. As the “explorer” continues upward along the trail, the character of the rocks changes to loose ash, pumice and scoria. These vary in color through shades of black to bright red. Such an accumulation indicates that the cone of Wizard Island was the site of explosive activity where the material was blown into the air and settled around the vent to build up the cone. Walking here becomes somewhat difficult. The angle of slope of the cone is as much as thirty five degrees. It is therefore typical of the usual cinder cone.
The steep slope of Wizard Island does not stop at the water’s edge. It must be remembered that the island has been built up from the floor of the lake which is 2000 feet at its greatest depth. This means that Wizard Island is itself quite a substantial volcano over 2700 feet high. It is a monument to the last volcanic activity of this immediate vicinity. Here is a case of a volcano within a volcano. There are two other smaller cones now submerged in the lake which are probably contemporaneous with the Wizard Island cone. They are east of the larger vent and were discovered when the Lake was sounded in 1886.
As one nears the summit of Wizard Island there may be seen on the Rim to the west the darkness of Llao Rock capped by a light yellowish material. The base of the rock cannot be seen but is of interest because it is a different type of lava from the others so far noticed. It is younger and is the type called dacite; that is, it contains a little more silica than the others. The base of Llao Rock is curved or U-shaped where it comes in contact with the lighter colored and older lavas. The logical thought is that the dacite is occupying an old valley which at one time extended up Mazama’s high slopes. This seems to be true, and what is more, the U shape indicates that it was a glacial valley. Mt. Mazama built a cone by successive outpourings of lava and explosions of ash and fragmental materials. Later, the cone accumulated snow and ice on its slopes and glacial valleys were formed. And, finally, one of these was filled by the lava which now forms Llao Rock. A glance to the east shows that glacial valleys were formed in other places too. The U shape of Sun Notch and Kerr Notch are particularly significant in this respect; and they are younger than the valley of Llao Rock. No lava flows over occupied their floors. On top of Llao Rock and other points around the Rim may be noticed a bright yellowish material which resembles a field of ripe wheat. This material is in reality a light rock of frothy appearance known as pumice. It was formed when molten lava containing a high percent of gas solidified while these gases were escaping, leaving it full of holes or air spaces.
On reaching the summit of Wizard Island a perfect crater is found. The crater is about five hundred feet in diameter and about one hundred feet in depth. The rim of the crater at some points is brilliant red, showing a high degree of oxidation. Most of the cinders, ash, and lava have a fused appearance, indicating the high temperatures which must have existed when eruption was in process.
By the use of a little imagination, one can here picture volcanic activity at its best. It is not hard to picture the crater emitting steam and hot gases and boiling sullenly with miniature explosions, while red hot molten lava restlessly moved about within it. Another striking thought is a realization that it could not have been so many years ago that such a scene would have been a reality. Certainly it could not have been many thousand years, and if the story told by the age of the trees on the island means anything, it was not many hundreds of years ago. The most recent estimate concerning the last activity of the Wizard Island cone, by tree ring count, is about 800 years. More than that could not be safely said, but certainly the lava and ash is as fresh as if put there yesterday and erosion shows practically no effects as yet. The general shape is that of a young volcano showing no dissection. It is in miniature an example of old Mt. Mazama which must have been of the same semi-explosive type. The absence of any signs of glaciation would tend to date Wizard Island as later than the last glacial period. At any rate, it is a very interesting thought to consider as the return down the slope is made and so back across the nor serene lake, once the scene of so many active and violent forces of nature.
The Birds of Wizard Island
By Berry Campbell, Ranger-Naturalist
On Wizard Island are found the birds of the mainland with a few exceptions. In general, the forest-inhabiting species are found there as on the Rim, while those which feed in the meadows are scarce or absent. As one walks through the trees on the trail to the crater, Purple Finches are conspicuous, and their incomparable song livens the woods. The Golden-crowned Kinglet attracts the curious with a song which sounds like tiny bells high in the tree tops.
These greenish midgets are not easily seen, for they spend their hours well up among the boughs, gleaning tiny insects from the needles. Occasionally they may be seen hovering up to the tip of a branch after the manner of a hummingbird. Keeping them company are the Audubon Warblers, whose merry “tsip” rings out as they fly through the forest – their yellow spots resembling patches of sunlight. If you are fortunate, you may see a family of them tramping through the woods. The juveniles noisily follow the adults who fill them with insect food. Red-Breasted Nuthatches climb up and down the trunk, vacuum-cleaning the crevices. Their nasal call may be heard at all times. With unexcelled industry, these fellows groom a large tree in very few minutes. Often associated with the Nuthatches are the Chickadees, with their cheery song – “chick-a-dee-dee.”
Although flycatchers abound, one seldom sees them. The clear call of the Olive-Sides, “What-peeves-you?”, follows one all the way up the cinder cone trail. Though it is not so noticeable, the “pee-ist” of the Western Flycatcher will be noted by the trained observer. The ease with which these birds catch insects in mid-air has led them to devote their whole time to the business, and their name is well earned. The Mountain Bluebird has followed their example and several may be seen at the top of the cone darting out from some vantage point at a helpless insect. Frequently heard in the deeper woods is the Hermit Thrush. Though a simple song of but three or four flute-like notes, the richness and the indescribable beauty of the sound make it a song unexcelled. Patient search will reveal that speckled-breasted virtuoso on a log or in some low tree.
Because of the dearth of meadows or grassy spots of any kind, Juncos and Robins are rare, although a few pair of each species breed on the island and in the afternoon their songs are sometimes heard. Chipping Sparrows, also ground-feeders, are absent or rare. The lack of soil, however, rather favors the Rufous Hummingbird, for its favorite flower, the Rock Mimulus, thrives in the loose lava slides. Often this nectar-feeding bird is the first bird seen on the island trip.
The bare rocky shores do not attract many waders – the only one which is at all common is the Spotted Sandpiper. The whistling “peetweet” of this bird may be heard up and down the shoreline, and towards, Skell Channel the species is quite abundant. As a person walks along the waters edge, these birds will often fly out over the water to land behind him, realizing better than their relatives the futility of running ahead of a man in an exploratory mood. Of the larger birds, Red-Tailed Hawks, Bald-Eagles, and Ravens have been seen, while a few ducks frequent the bays and inlets.
