Pichincha in Ecuador, an extinct volcano, is situated almost immediately on the equator. It has a height as measured by Whymper by the barometer, of 15,918 feet above the Pacific. The summit is covered by blocks of pumice. Several species of lichens are found at this elevation. According to Daubeny, Pichincha was extinct prior to 1539, when it became active. There were also eruptions in 1577, 1587, and 1668. It was also in activity during 1831.
Cayamba, another volcanic mountain of Ecuador, lies to the east of Pichincha, a short distance north of the equator. Its height is 19,186 feet. It is nearly extinct.
Cotopaxi, 19,680 feet, is another volcanic mountain of the high plateau of Quito. Cotopaxi is still active. Its slopes are covered with snow down to a height of about 14,800 feet. Between the lower edge of this snow line and the lower slopes of the mountain, there lies a zone of naked rock.
According to Whymper, the eruption of Cotopaxi, in 1877, was preceded by an unusual degree of activity in the earlier parts of the year. This, however, did not cause any alarm until June 25th, 1877, when, shortly after midday, an eruption, attended by tremendous subterranean roars, began, and an immense black column shot up into the air for about twice the height of the cone. This eruption was clearly visible at Quito, for the wind blew the ashes towards the Pacific. At this time the summit had not changed its appearance, but towards 6:30 A. M., on the next day, another enormous column of ashes rose from the crater. The ashes and cinders were first carried due north by the winds, and then, spreading out in all directions, were subsequently distributed through the air all over the country. At Quito, as early as 8 A. M., the sky assumed the appearance it generally has at twilight, and the darkness increased until midday, when it became as dark as at midnight. Indeed, it was so dark that one could not see his hand before his face.
During this eruption, as is very common in the eruptions of the snow-clad mountains of South America, a flood of water, due to the rapid melting of the snow and ice on the summit, rushed down the mountain slopes at 10 o'clock A. M., on the 26th of the month, almost immediately after the appearance of a stream of lava that began to flow down the mountain. In a few moments the mountain was completely shut off from view by immense columns of steam and smoke. At first, a low, moaning sound was heard, which rapidly increased to a roar, when a deluge of mud, mingled with huge blocks of ice and stones, swept down the mountain, leaving a desert in its path. It is estimated that at some places this stream moved with a velocity of fifty miles per hour.