PUBLIC PARKS OF IOWA 133 



winds of summer have blown the rock areas bare and clean as a city 

 pavement, and the wind-blown sands and dusts have rounded off all 

 corners and polished all surfaces until the hard vitreous blocks appear 

 as if fused in a furnace, without seemingly making any marked impres- 

 sion. Continental glaciers have repeatedly passed over the region, planing 

 off the glassy masses as a joiner does his beam of wood, and deeply groov- 

 ing the smoothed facets as by some giant graver. Compression and arch- 

 ing of the earth's crust have uplifted the country into mountains, but 

 they have signally failed to destroy the rocks. 



The sudden appearance and rapid decline of the Siouan mountains on 

 the mid-continental horizon are incidents of the Mesozoic age of geologic 

 history. Brief, brilliant, almost pathetic are the succession of chief 

 events. The main uplifting took place during the Triassic period. In 

 the succeeding Jurassic and Comanchan times all of the ranges were 

 completely razed to the present plains-level. During Cretacic time the 

 waters of the ocean again rolled unbrokenly over the old base-leveled 

 region, and the bared foundations of the former mountains formed the 

 bottom of the broad epi-continental sea. No great orogenic uplift was 

 ever more rapidly or more completely obliterated. It is one of the mar- 

 velous episodes in the long history of the North American land contest. 

 In still another way the Siouan area is quite notable perhaps the most 

 remarkable spot of our country. It is one of the completest of outdoor 

 laboratories for geological instruction. With an areal extent scarcely 

 larger than that of some of our larger cities, it is a unique study ground. 

 It is a veritable geologic multum in parvo. In this circumscribed dis- 

 trict is represented every known category of the geological agencies. 

 The whole panorama of geological science is spread out before one's 

 eyes. Apt illustration abounds of the major phenomena pertaining to 

 the origin, structure and modification of the earth's crust. 



The Siouan area is a locality where the cardinal principles of earth 

 science may be best taught by example and in the least possible period. 

 In a week's time the entire list of princal processes and products may 

 be passed in review in the field. In going to and from this spot another 

 week's time permits examination of the most complete stratigraphic 

 section of the continent and a review of the evolution of life generally. 

 As the culmination of a year's study of geological science indoors this 

 place is well worth a visit by every college student and teacher in geol- 

 ogy. It is, in fact, the most typical, most compact, and illuminating area 

 yet revealed wherein students may perform in a little while extensive 

 geologic field work of a most practical kind. It is here that the outlines 

 of field geology are acquired at a glance. The foundations are here 

 quickly laid for all broader and subsequent geologic excursions into the 

 farthermost points of earth. 



The realm of the ancient Siouan mountains is also famous in poetry 

 and Indian lore. Principal scenes of Longfellow's "Song of Hiawatha" 

 are laid here, although when he wrote the epic it is not probable that 

 the poet had ever been nearer the place than the Cambridge gardens 

 on the shores of Back Bay. 



