126 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



OUTCROP is illustrated. The steps formed by the thickness of the 

 card stratum at the same time illustrate another phenomenon and its 

 verbal sign, these being miniature ESCARPMENTS. 



" The term DIP, and that which it expresses, may be illustrated 

 by tilting the map ; as a whole, when all the strata will dip towards 

 the lower end ; or by placing a small object beneath some of the sti-ata 

 and pressing them down on either side of it, when those strata will 

 dip from it in each direction. In the latter case the upraised portion 

 will represent what is known in nature as an ANTICLINAL ridge. 

 If a second object be placed at a short distance from the first and 

 the strata be depressed between them a SYNCLINAL trough will 

 be formed 



" Whilst illustrating DIP, another term usually very perplexing 

 to learners, may, by means of the Strata Map, be most readily ex- 

 plained, viz. : STRIKE. 



" By removing portions of overlying strata geological INLIERS 

 are clearly exhibited ; and OUTLIERS are shown by means of a 

 portion of the stratum to which they belong cut to the shape of the 

 outlier to be represented and attached to the underlying stratum in 

 the proper position. 



"The strata of the map being all superimposed, horizontally, one 

 upon the other, that condition of things known to the geologist as 

 CONFORMABLE stratification is exhibited, and UNCONFORM- 

 ABILITY is easily explained. 



" Where IGNEOUS rocks occur within the area represented, the 

 space so occupied is marked by a distinctive colour indicating such 

 intrusion. But as it is usually impossible to say whether under- 

 lying st7-atijied rocks are pierced thereby, their presence is not indi- 

 cated on underlying strata. In any case where, by the operations of 

 the miner or otherwise, such rocks are found to exist, the fact may 

 be indicated on any stratum affected. 



" The Strata Map may be made of any size, and may consist of a 

 small n\imber of layers representing groups of formations or of a 

 large number representing the several foi^mations or their sub- 

 divisions. 



" Upon the various strata, FOSSILS, characteristic of the forma- 

 tion repi'esented, may be figured and na-med. 



