[9] COLLECTING AND PEEPARING FOSSILS SCHUCHERT. 



susceptible of change than others.^" In such regions, look over the old 

 weather-worn rock surfaces, since the chances of finding fossils there 

 are usually far more favorable than on fresh fractures. Localities of 

 this kind usually yield few and poor fossils, but these are of the greatest 

 interest to the geologist for determining the age of the strata in question. 



Localities new to the collector. — In searching for localities new to the 

 collector, one way is to begin by asking local school-teachers or drug- 

 gists if there are any collectors of fossils in the vicinity. If such a 

 person can be found, directions to localities will generally be given. As 

 a rule, however, one has to. depend upon himself in this matter, and it 

 is advisable to begin by looking over the refuse i^iles of quarries and 

 the cuttings along railroads and turnpikes, or to search the banks of 

 streams and hillsides for natural rock exposures. If organic remains 

 occur, these are, as a rule, most easily seen on weathered surfaces, since 

 the fossils are nearly always of a mineral composition different from 

 the matrix in which they are buried, and therefore weathered differ- 

 ently. Friable sandstones, however, often fail to show traces of fossils 

 on weathered surfaces, even when they are quite abundant within. 

 Loose drifted rocks in the beds of streams generally will indicate, ou 

 breaking them, whether fossils abound in the vicinity, and the amount 

 of wear will afford some clew as to the distance they were transported. 

 These "lost rocks" often serve as leaders to fossiliferous strata. Exter- 

 nally they are of no value as specimens, but when broken may yield an 

 abundance of good fovssils. 



A list of some important Korth American localities for fossils is 

 given in an appendix to this iDaper. 



Stone walls. — In many regions stone walls furnish excellent fossils, 

 the rock being usually derived from strata in the immediate vicinity 

 of the wall. Examine the fields around these walls, particularly after 

 the spring rains, as such localities are occasionally productive of free 

 fossils. 



Rocic ballast. — Broken rocks on which railroads are laid are some- 

 times good places in which to collect, but caution is required lest sev- 

 eral geologic horizons become mixed. Trackmen usually give the 

 sources of such rocks. 



Gravel pits. — Sometimes fossils are found in gravel pits, but are 

 usually very much worn. In certain regions, however, notably in 

 Michigan, very good fossils are found in such places. These trans- 

 ported fossils may have an interesting tale of travel to tell. In Min- 

 nesota it is not rare to find fossils in the drift from Manitoba, while in 

 the Ohio Valley ijieces of native copper are sometimes picked up 

 which were transported from the Lake Superior copper region by the 

 great glaciers from the north. The value of drift fossils, however, is 



^Geikie, Text-Book of Geology, 3d ed., p. 319. See also James D. Dana's Text- 

 Book of Geology, 4tli ed., p. 309, 1895. 



