468 BISECTIONS TOR COLLECTING FOSSILS. 



remnants of broken-up beds of lakes or seas (for botli kinds 

 have often been indiscriminately called alluvial), &c. He 

 will often find them to contain well-preserved remains, such 

 as teeth and bones of the elephant, hippopotamus, rhinoceros, 

 petrified wood, &c. Also, interesting mineral substances, 

 such as particles of metallic ores, gems, &c., are frequently 

 found imbedded in those deposits of loose materials ; 

 let him carefully collect, label, and preserve such objects. 

 "With regard to loose blocks, specimens should in general be 

 detached from such only, as, from the situation in which 

 they are found, and from other circumstances, have evidently 

 not formed part of neighbouring masses, and which are, 

 therefore, called erratic blocks. Masses of cliffs and rocks 

 precipitated from above, at recent periods, may, however, 

 often supply the collector with good specimens of strata not 

 easily accessible to him. Materials for roads, thrown out in 

 heaps, may furnish specimens for collections ; but the places 

 from whence they are obtained should be previously ascer- 

 tained. Eoad-stones are frequently brought from very distant 

 quarries. 



2. Upon the whole, rock specimens should be taken fresh 

 from the masses in their native places. Among localities 

 most favourable for this purpose, the following may be 

 specified : cliffs on the sea-shore they frequently afford 

 very perfect sections of the masses and strata of rocks ; pre- 

 cipitous sides of rivers, and their beds, and of mountain 

 streams, which often lay open strata and beds at depths 

 otherwise difficult to discover; ravines and deep valleys 

 transversely crossing the strata, and the naked sides of 

 which, especially when long operated upon by rivers and 

 mountain torrents, often present instructive profiles of 

 ytratification ; artificial sections of ground, such as are pro- 

 duced by quarries, gravel-pits, and excavations, of every 

 description, for roads, canals, tunnels, wells, &c. 



3. Where mines are worked, the collector will generally 

 find some well-informed person or other to assist him in his 

 pursuits ; but he should use circumspection in making 

 purchases of specimens from the common miners. 



4. Not unfrequently, one and the same mass of rock 

 exhibits great diversity of aspect, through the variation 

 which takes place in the mixture and proportion of its com- 



