96 RASTALL : THE INGLETO^'IAX SERIES OF W. YORKSHIRE. 
characteristic suture-jointing which is produced in quartzose 
rocks by metamorphism. Strain-shadows are also well seen. 
In some of these quartzite pebbles the texture is very coarse, 
but there are also numerous examples of finely crystalline rocks 
of similar composition. In some of these foliation is conspicuous. 
Others show granulitic structure very well, and in many of 
these w^ater-clear recrystalhsed felspar is probably present in 
addition to quartz. 
There are also many fragments consisting of quartz, with 
or without recrystalhsed felspar, and abundant mica, either 
muscovite or a pale green biotite. Xo brown biotite was ob- 
served. These quartz-schists and gneisses show very well- 
marked parallel structure due to foliation, and they frequently 
occur in long narrow fragments, which are often slightly bent 
by subsequent pressure. Besides the strongly foliated gneisses 
and granulites there are also rocks having the composition of 
granites and syenites, which show little or no foliation. The 
strain-shadows which sometimes occur in the quartz of these 
rocks may be due to the crushing which they have undergone 
subsequent to deposition. There are also a few chips of well- 
developed granophyres, so that it is evident that a considerable 
part of the detritus was derived from an area of acid intrusive 
rocks. Xo undoubted basic intrusive tv^es have been recognised. 
It is noteworthy that a large proportion of the felspar of these 
acid intrusives is of a perthitic character, and one or two frag- 
ments of a coarse microcline-perthite-pegmatite or graphic 
granite may be specially mentioned. A fair proportion also 
of the simple felspar grains show perthitic structure. 
It is impossible to describe in detail the numerous rock- 
types of an intrusive and metamorphic character which are to 
be seen in these slices : it must suffice to say that the most 
conspicuous elements among them are a great variety of rocks 
which show conclusive evidence of having been derived from an 
area of intense dynamic metamorphism (Plate VIII.). 
Rocks of hypabyssal character are much less abundant, but 
quartz-porphyry and porphyry can be identified. Some of these 
have been much crushed. However, part of these may have 
been lavas rather than intrusions, and in most cases it is true 
