FLffiTZ TRAP FOUMATIONS. 801 



of llie sand, or from otiier causes, insulated poi lions of tlie 

 upper part of this fortnaiion have resisted the action of the 

 water, and of the various aj>;cnts which have broken down 

 and removed the adjacent parts. 1 hese portions have pro- 

 tected and preserved entire 'he coUimns of louse sandstone 

 on which tliev rested. One of these singular liills. called the 

 Castle Hock, of which Mr. Seymour has preserved a sketch, 

 when seen from a little distance, presents tlie appearance of 

 columns, porticos, arches, ^c, having a most striking re- 

 semhlance to an architectuial ruin. 



One of the fust con<ideral)le trihutaries which the Arkan- 

 saw receives from the north, after it enters the plains, is 

 called the Boiling-spring Fork. It has received this name 

 hom a large and uncommonly beautiful spring of water, si- 

 tuated upon it immediately at the foot of tlie mountain. 

 'I'his spring is but a few rods from the commencement 

 of the granite, wliich there rises into what is called by Pike 

 the " highest peak," and issues from a chasm in a stratum 

 of fine compact sandstone of a deep red colour, which re- 

 poses against the granite at an angle of near forty degrees. 

 A short distance to the right, this sandstone is succeeded bv 

 an extensive bed of silicious breccia resting against the gra- 

 nite in a similar manner. This agii;regatc consists of coarse 

 angular fragments of hornstone, jasper, and other silicious 

 minerals, firmly cemented. It is also of a red colour, and 

 abounds in iron. 



The spring above mentioned tlirows out a consideral)le 

 quantity of water, perhaps fifty gallons per minute, and also 

 about an equal volume of an aeriform fluid. The water is 

 lin)pid and colourless, and when freed by Ijoilifig from t!ic 

 carbonic acid whicli it contains, is entirely without taste. 

 Immediately on comins: in contact with tlie aii'. it is covered 

 with a pellicle of carbonate of lime, which substance has 

 been so copiously deposited as to form a capacio\is bason 

 overhanging a considnrable stream of water, and luoks 

 as if chiselled from the whitest marble. The risinij ol' thr 



