A CENTURY OF GEOLOGY IN INDIANA. 135 



About 20 pages and four plates of the 1874 report are given to a chapter 

 on "Antiquities," based upon an investigation made by Mr. Cox and F. 

 W. Putnam of the Peabody Museum in the fall of 1874. A full description 

 of the stone fort at the mouth of Fourteen Mile Creek and of other earthworks 

 in Clark and Jefferson Counties is given, with illustrations of their plans, 

 and of stone pipes and other objects taken from them and other mounds 

 throughout the State. 



Under his description of Jackson County, Cox states that in the vicinity 

 of Roekford a thin limestone "passes upward into greenish gray, hard, cal- 

 cerous shale, filled with fossil cephalopod shells, in a fine state of preservation. 

 The Goniatites and Nautili of this locality are among the most interesting fos- 

 sils found in the country. They are eagerly sought for by collectors and have 

 given to Roekford a world wide notoriety. The rock is easily decomposed 

 when exposed to the air and its fossils are found ready weathered out on the 

 newly exposed surface after floods in the river. The children of the village 

 keep a sharp lookout for them and the outcrop, which is only two or three 

 feet thick, and from 150 to 200 feet long, is diligently searched from day to 

 day after each freshet or heavy rain. Large numbers are collected and sold, 

 for what they can get, to the scientists who are attracted to the locality. 

 They go by the name of "snake rocks" and if you ask for Goniatites or Nautili, 

 as I did, you will be told that they know nothing about such things, but on 

 the other hand, if you inquire for "snake rocks" you will find that nearly 

 every boy and girl in the village will have a few and are ready for a trade." 



In the report on Brown County, Collett tells how the ridges of Knobstone 

 withstood the onward movement of the first glacial invasion of the State, so 

 that all the land directly southward comprises a driftless area. He says: 

 "Approaching the central areas from the east, from the west and from the 

 valley of Bean Blossom Creek at the north, it was found that the county was 

 enclosed by a wall of hills ranging from 350 to 450 feet in height. In valleys 

 to east, west and north, glacial drift was present, mounting well up on the 

 sides of the hills. But within this walled space the scarcity or entire absence 

 of boulders showed that the ice drift had only for a short period, or never 

 intruded, Bean Blossom Ridge marking the extreme southern limit of the local 

 glacier foot. Against and upon this wall-like ridge the stranded ice seems to 

 have been continually massed and melted by each recurring summer's sun. 

 It sent torrents of water south across the county, wearing slight depressions 

 in the ridge as at Low Gap and the source of Greasy Creek, bearing fine sedi- 

 ment, some gold dust and black sand, and but few or no pebbles or boulders. 

 The long continued melting of ice loaded wdth the most enduring debris of 

 the Laurentian rocks, as greenstone, quartzite, quartz, gold and magnetite, 

 deposited large quantities of these imported materials in Bean Blossom Val- 

 ley. The rapid current of the ice water would naturally carry down stream 

 the lighter sand and gravel, and sort out and leave behind the heavier rocks, 

 gold and magnetite in considerable quantities. Still above the outside wall 

 of the county, several peaks, notably the Weed Patch Knob, rise from 50 



