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Notes on Paricutin volcano - 
These were immediately followed by hige irregular masses of orange colored 
lava, which falling upon the slopes of the cone made brilliant cascades of 
glowing rocks. (Note: During the daylight hours the ejected masses showed 
many irregular, elongated shapes) These arcs gave advance notice by a vivid 
lighting of the ash cloud above. The arcs were accompanied by temendous roars 
of noise and blasts of air, sometimes sufficiently strong to blow open the 
door of the casita. 
June 10 - 
12 AM- A vivid electrical storm to the southeast of the volcano. 
2:10 AM - The tramendous roar of the volcano suddenly ceased, there being 
one last tremendous blast about one minute after the general roar. After this 
last blast I ’vent to the door of the casita but could not make out the cone. 
Everything was ghostly still in the striking contrast to the tremendous din a 
few minutes before. In a few minutes I could perceive a large dust cloud and 
an occasional incandescent rock rolling down the cone’s side. TJhen the dust 
cleared a huge notch was evident in the profile of the cone. 
Earlier in the evening (about 9 PM) I noticed an almost imperceptible 
offset in the north rim of the cone. This can be seen in one of the photographs 
I took at that time. At 12 AM this had developed into a perceptible sag. 
Immediately after the lifting of the dust clouds there was a beautiful 
fountain of incandescent rock from the crater, the bursts following each other 
in rapid succession, most of them without noise except the patter of falling 
rocks upon the cone, or at most feeble noises. This continued until the next 
morning. 
In the morning (June 10) one could see that a large section of the north 
side of the cone had slid down forming a huge caldera-like cut in the previously 
symmeteical cone. The break covered about 45 degrees of an arc of the original 
cone. The east and west breaks were sharp, with steep walls, and the slumped 
portion stepped down the terraces (two long ones). The crater was very quiet 
with only an occasional burst of rock, but with a normal smoke cloud. 
The lowest terrace, beginning at the east break in the cone sloped about 
5 degrees to the east. The western and lower end showed an area of reddish 
oxidized rock and an occasional fall of rock accompanied by a reddish dust. 
This portion was obviously in motion and at 11 AM flowing lava appeared. 
The lava front advanced about 30meters per hour at the beginning but soon 
slowed down. At 3:45 PM it had advanced about 50 meters. The height of 
the lava front, where it broke from its ash cover, was about 15 meters high 
and at its flowing front about 3 meters. 
The front of the lower terrace, with an angle of repose for the loose ash 
cover, also advanced slowly to the north by the continuous sliding dovai of the 
ash, as the front slowly advanced. 
The lava itself, advanced by large blocks breaking off and rolling down 
the front and by the almost fluid-like triekfel/ of red hot fragments that con- 
tinually spalled off. The lava front was red only in the cracks and disinte- 
grated with a continuous crackle to which was added the tinkle of sliding rock 
fragments. The color of the hottest lava was orange red. No visible fumes 
were given off and there was no perceptible odor. 
The volcano was quiet all day with only smoke column. 
7:40 P. M. There suddenly appeared at the northwest base of the cone, 
a thin column of white smoke, larger than the fumaroles and within the main 
portion of the old flow where there were no fumaroles. Within a minute or two 
the base of the smoke column appeared red, increasing rapidly in intensity. 
We immediately hastened to the spot, crossing on our way an area of greatly 
disturbed ash and some pressure ridges, and found a low cliff of rock with 
