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trict, except along the southern border, where, as for example, 

 northwest of Flenciington, it may be seen following the direc- 

 tion of the altered strata. It is likely that numerous dikes of 

 trap do exist, especially next the southwestern limit of the table- 

 land, but concealed beneath the soil, or perhaps existing as narrow 

 injected veins, not reaching the surface of the rock. The regular 

 stratified structure and northwestern dip of the strata seem, 

 however, not to have been changed, even where the rock appears 

 to have undergone the most decided alteration in all its external 

 features from the extremely elevated heat, to which it has evi- 

 dently been subjected since its original deposition. There is a 

 frequent alternation of the highly indurated beds with others, exhi- 

 biting but little departure from the commoner features of the red 

 shale and sandstone. 



In the range of country northeast of this tract, the strata, ex- 

 cept where intersected by some trap ridges, hereafter to be men- 

 tioned, seem to have sustained no corresponding alteration of 

 texture and colour; nor are the changes which appear in the 

 rock for a small distance from the trap which occurs in that 

 region, of precisely the same nature as witnessed in the strata of 

 the Swamp. 



The next belt of the formation which we meet with in our pro- 

 gress northwestward, commences at the verge of the altered or 

 indurated rocks of the Swamp, and extends nearly to the Nischi- 

 sakawick creek. 



In a part of the series the rock is a compact fine-grained, but 

 somewhat argillaceous, red sandstone, splitting into regular flag- 

 stone ayers, which render it a convenient building stone, for 

 which purpose it would seem to be, in other respects also, well 

 adapted. Its colour is a brighter red than that which distinguishes 

 the set of beds that next overlie it. 



Between the upper border of this more arenaceous tract, and 

 the southern edge of the variegated calcareous conglomerate, one 

 mile north of Milford, the predominant material is a very argilla- 

 ceous sandstone, with much soft friable shale, the whole being of a 

 deep reddish-brown colour. This extends over a width, measured 

 along a straight line parallel with the river, of about four miles. 

 The Nockamixon cliffs, upon the Pennsylvania side of the river, 

 exhibit a fine display of these upper beds. The angle of dip to 



