On Certain Conglomerates near Sydenham. 49 



quartzite, porcellanite, and quartz-porphyry. These pebhly mud- 

 stones have a thickness of about seventeen feet near the water's 

 edge. The matrix is exceptionally somewhat sandy. They are 

 followed by a heavy coiiglon)erate of pebbles of similar character 

 to those in the mudstones, but reaching larger sizes, nearly a 

 foot in diameter, and a few additional rocks were observed, 

 including a greisen. 



The pebbles are thickly crowded together, and in various 

 positions, the spaces between large material filled with smaller, 

 and the small quantity of fine material is mainly sandy. The 

 junction with the underlying pebbly mudstones is very uneven ; 

 the conglomerate is about 15 feet thick at the water's edge, 

 but contemporaneous erosion has cut away the mudstones higher 

 up the bank and allows the conglomerate to thicken to about 22 

 feet. In the upper part of the conglomerate there occur two 

 irregular bands of sandstone about 9 inches thick and with few 

 pebbles in them. 



The upper surface of the conglomerate is fairly even and is 

 succeeded by a series of pebbly mudstones, similar to those below, 

 for about 40 feet. Then follows an alternation of thin sandstone 

 beds and mudstones, both free from pebbles for about 24 feet. 

 Another band of about 4 feet in thickness and containing 

 pebbles then occurs. The matrix is mainly mudstone but it 

 contains a discontinuous bed of tine sandstone, which, at one 

 place, is folded back on itself, and at another disturbed from its 

 position parallel to the beds. In the upper part of the mudstone 

 and above this sandstone is a band of coarse grit. The next bed 

 following is a sandstone free from pebbles and the pebbles were 

 not observed further at this place. 

 The series may be tabulated thus : — 

 Uppermost, eastern end : 



Mudstone, with pebbles, and grit band 



and fine sandstone bed disturbed - 4 feet 



Alternating mudstones and sandstones, 

 without pebbles - - - - 



Pebbly mudstones - - - - - 



Heavy conglomerate - - - . 



Pebbly mudstones - - - - - 



Total 



