How different from the pellucid basin of the Great Geyser! Lord Dufferin tells us that he 'brewed his coffee in the Geyser water.'
The mud boils like the angry lava-waves of a volcano; it is always of a very high temperature, and occasionally runs over the rim of the basin, but never rises violently into the air. It looks like black sulphur (bitumen), and has a brimstone smell. Certainly it is a diabolical pit, and worth coming far to see, but it shows none of the phenomena which tempt travellers to Iceland.
It more closely resembles the salses or mud volcanoes of Central and South America, and is a phenomenon very common on the sides of volcanoes. As far back as the time of Pliny it was observed that 'in Sicily eruptions of wet mud precede the glowing (lava) stream.'
Humboldt recognizes in the 'salses, or small mud volcanoes, a transition from the changing phenomena presented by the eruptions of vapor and thermal springs, to the more powerful and awful activity of the streams of lava that flow from volcanic mountains.'
Although the recent discovery of the Devil's Cañon in California makes it impossible to say at what time, if ever, this smothered volcano may have been more active, we have accounts of analogous phenomena in Central America and San Salvador, in the Ausoles of Ahuachapan, near the volcano of Izalco, which were described in 1576 by Licenciado Palacio, and also in what was called the 'Infernillo,' on the side of the volcano of San Vicente, which was mentioned by the Spanish Conquistadores. We also know something of the subsequent history of these volcanoes; for M. Arago has remarked that
'The volcano of Izalco is extremely active. Among its eruptions may be cited those of 1798, 1805, 1807, and 1825. On the occasion of the last eruption the course of the river Tequisquillo was altered to the extent of several kilomètres.'
Also:
'The volcano of San Vicente, called also Sacatecoluca, was distinguished in 1643 by a very violent eruption which covered all the surrounding country with ashes and sulphur. In January, 1835, a new eruption of this volcano destroyed many towns and villages.'
Now let us see what old Palacio says of the springs on the side of this fearful volcano of Izalco:
'The springs, which the Indians call 'Hell,' are all within the space of a gunshot across, and each makes a different noise. One imitates the sound of a fuller's mill; another that of a forge, and a third a man snoring. The water in some is turbid; in some clear; in others red, yellow, and various colors. They all leave deposits of corresponding colors. Collectively the springs form the Rio Caliente, running underground for a quarter of a league, and so hot on reaching the surface as to take the skin off a man's feet. Double the range of a musket shot from these springs are others, which flow from a rock fifteen feet long by nine feet broad, split in the centre, sending out with water columns of smoke and steam, with a fearful sound, distinguishable for half a league.'