The first lava to escape moved slowly the attitude of down the glacial valley. Perhaps at an s to the dip at early stage a dome formed above the ion shows the orifice, and as this continued to grow by flow before andesites and by expansion from within, the concentric flow bands were disrupted in the central parts and unfolded like the petals of an opening bud. Shortly, the lava filled the old glacial valley and spread onto the surrounding flats.
With a little care, one may examine the flow on the west side. At the base, the dacite is a jet-black glass, streaked in shades of pink and gray. In many places it is highly autobrecciated, and the shattered bottom is rucked up, forming many small caves. Within and just above the blocky basal layer, the flow planes are contorted into flat, recumbent folds, suggestive of viscous drag. Higher up, the contortion rapidly disappears, and the flow planes become smooth and regular. At first they dip into the caldera wall at low angles, conforming to the valley floor; farther up the cliffs, they become horizontal and then gradually the dip changes in direction, becoming increasingly steep and finally, near the surface, becoming vertical.
Beyond the caldera rim, the lava is almost entirely concealed by a blanket of pumice. Clearly, however, the surface of the flow has not been greatly eroded and preserves much of its original form. Only the low fringes of the lava were later covered by ice. The crust must once have bristled with black, glassy spines and turrets and been littered with angular blocks of obsidian. The attitudes of the flow planes (figure 10) resemble those seen in the Watchman, Cleetwood, Grouse Hill, and Redcloud lavas.
When the new highway was made to Diamond Lake, a cave was discovered at the edge of the Llao flow. Allen1 records that it measures 20 feet long and between 10 and 15 feet in diameter, and that many tributary channels a foot or so across ramify downward from the floor. On the roof of the cave he found abundant specular hematite, some of it in beautiful dendritic forms.
