PEALE.] PHYSICAL FEATURES OF DEPOSITS MOUNDS, ETC. 



403 



MOUNDS AND CONES OE CRATERS. 



A comparison of the various illustrations in Part I will show the great 

 variety assumed by the cones and mounds of the geysers of the Yellow- 

 stone Geyser Basins. They may be simple basins, surmounting a tube, 

 as in the case of the Grand and Saw Mill Geysers, sections of which are 

 shown in Figs. 23 and 26a. In these geysers we really have no cones. 

 Such is the case also in the Giantess (see Fig. 25), which is a huge glob- 

 ular basin or bowl in a mound of laminated geyserite. Others, as the 

 Fountain Geyser of the Lower Geyser Basin, are basins with mounds 

 just beginning to be formed where the water falls from the column dur- 

 ing eruptions. The building up appears to be mostly on one side. A 

 similar one-sided arrangement is seen in the crater of Old Faithful, as 

 though the prevailing winds were from a certain direction, and caused 

 the water to fall mainly on one side. In the Gibbon Geyser Basin there 

 are geysers without any cones, or even any siliceous deposit, except what 

 is just beginning to coat the rocks in which they are situated. This 

 argues against Bunsen's theory that the deposit of silica is necessary 

 to the existence of geysers. We shall have more to say of this farther 

 on. Where we have mounds or cones we see that they present differ- 

 ent characters. Compare, for instance, the cone of the Bee Hive with 

 Old Faithful, or the Castle and Grotto with the Giant. In the Giant 

 the cone is on a platform, and it seems as though before the latter was 

 built the condition may have been similar to that of the Great Fountain, 

 in the Lower Geyser Basin. The Castle also seems to have passed 

 through several stages. To form the broad mound upon which its plat- 

 form rests we must imagine a large bowl, with regular overflows to make 

 the laminated deposits of this mound. Then, later, the platform was 

 built on this mound, and still later again the cone or present crater of 

 the geyser. None of the Yellowstone geysers present the simple form of 

 the Great Geyser of Iceland (see section in Fig. 22), where a saucer-like 

 basin surmounts a tube of 72 feet in length. 



In the following table the sizes of the cones of the Yellowstone 

 National Park are compared with the Great Geyser and some of the 

 New Zealand cones : 



Name.' 



Location. 



Size at top. 



Size at the base. 



Height. 



Union 



Minnte Man. 



Clepsydra . 

 Flat, cone.. 

 Steep, cone. 

 Bee Hive .. 



Turban 



Grotto, cone 1. 

 Grotto, cone 2. 



Giant 



Old Faithfnl.. 

 Castle 



White Pyramid. 

 White Dome ... 

 Great Geyser... 

 Waikite 



Shoshone Geyser Basin . 

 do 



Lower Fire-Hole Basin. 



do 



do 



Upper Fire-Hole Basin. 



.do. 



-do. 



-do. 



.do 



-do. 



.do 



.do 



55 feet diameter. 

 55 feet diameter. 

 3by4feet 



11 by 23 feet.... 



18 feet circumfer- 

 ence. 



46 feet circumfer- 

 ence. 



10 by 15 feet 



20 feet circumfer- 

 ence. 



8 feet diameter.. 

 20 by 54 feet . . . . 

 20 feet diameter. 



28 by 26 feet 



19 by 26 feet 



24 bv 25 feet 



145 bv 215 feet . . . 

 120 feet circum- 

 ference. 



Lower Geyser Basin. 



Iceland 



Kew Zealand 



56 feet diameter. 



101 by 75 yards... 

 100 feet 



3 feet. 



3 to 5 feet. 



3 feet. 



15 to 20 feet.* 

 20 to 25 feet.* 

 3 feet. 



3 feet. 

 8 feet. 



4 feet. 



10 feet.t 



11 feet. 

 llfeetllinches.{ 



25 feet. 

 2.') feet. 



12 feet. 

 15 feet. 



♦These are in the Sentinel Group and have springs on their summits that are 8 or 9 feet in diameter, 

 and have rims to 8 inches high. 



tTheso are dimensions of the cone only. It rests on a platform that is 4 feet high and has a circum- 

 ference of 342 yards. 



jThis rests on a j)latform measuring 75 by 100 feet, and 3 feet in height, and the whole mass, platform 

 and cone, is on a mound of deposit 40 feet thick and covering 3i acres. 



