COLLECTING AND PREPARING. 805 



tologists. Weathered surfaces where rocks are close to the surface 

 also make excellent collecting grounds. Stone walls and fences 

 may be a prolific source of weathered fossils. Very little can be 

 accomplished by attacking vertical cliff faces either natural or 

 artificial. It is better to attack the loose fragments quarried off or 

 fallen through the process of weathering. In cliffs long exposed, 

 the talus at the base is the best hunting ground, great care being 

 necessary, that the fragments collected from are correlated with the 

 beds in place. When no such fragments are available, quarrying 

 will have to be resorted to. Weathered limestone surfaces are 

 very satisfactory hunting grounds, but weathered sandstones are 

 generally less satisfactory since the shells weather away and only 

 external and internal molds remain. In such cases, if the cavities 

 showing the former presence of the fossils are numerous, it is best 

 to take large masses of the rock and ship them to thfe laboratory, 

 where the further breaking up should be done. Never try to ex- 

 tract the fossil from the sandstone or limestone in the field. Take 

 as much of the matrix as cannot be safely removed, leaving the 

 further cleaning for the laboratory. Many a good specimen has 

 been spoiled in the attempt to clean it in the field. 



vShales should be broken or pried off from the river bank or cliff 

 in large masses and then split. It is useless as a rule to attack a 

 vertical shale bank and attempt to extract delicate fossils. The 

 weathered talus at the base of all but actively undercut shale banks 

 generally furnish a rich supply of the more delicate fossils of the 

 shales. These should be placed between layers of cotton batting in 

 small boxes, the size of the box selected depending upon the 

 abundance of these specimens. Always have the box filled before 

 it is packed away, and with a label on the inside. When filled add 

 sufficient cotton batting or paper to prevent movement of the fossils 

 when the box is shaken, tie down the cover and write the locality 

 and bed on the outside as well. 



The beginner should be cautioned to be on his guard against 

 rockfalls as a result of prying off masses of rock near the base of 

 the cliff. This is especially the case in much jointed cliffs, where 

 the prying off of a mass near the base of the cliff may loosen the 

 masses higher up. 



Shales as a rule split better when wet; after drying they are 

 more brittle and break cross-wise. 



