J. H. A. Whealler—Boulders of Cambridge Gravels. 205 
The latter calls for special caution owing to its great similarity 
to the Silurian Orthoceras Limestone from South Sweden. Unless 
a specimen contains a fossil it 1s impossible to state definitely which 
rock it is. 
Noticeable under this heading is the Paleolithic implement 
found by Professor Marr, which is made from a silicified oolite 
which Dr. Rastall has identified as being of Yorkshire origin. The 
rocks from unknown localities are as follows :— 
(a) Metamorphic : 
Garnet-mica-schist. 
Hornblende-schist, with quartz veins. 
Green mica-schist, turning brown in places. 
Micaceous schistose conglomerate (quartz pebbles). 
Gneissose granites (comparatively common). 
Foliated granite with porphyritic microcline. 
Very much altered gabbro. 
Gneissose muscovite-biotite-granite. 
. Many quartzites of varying composition. 
Muscovite-granite-porphyry. 
Microgranites, chiefly pink. 
Many granulites. 
Many granites. 
.. Pegmatite. 
Markfieldite. 
Dolerites (common). 
Felsite. 
Basalts (common). 
10. Three types of rhyolites. 
The last is an important point, owing to their practically negligible 
development in the east of Scotland. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
(b) Igneous. 
1 
2 
3 
4 
5 
6 
7 
8 
9 
0) 
(c) Sedimentary : 
1. Carboniferous chert. 
2. Arkose (Sparagmite). 
In conclusion I should like to express my gratitude to Dr. Bonney 
and Dr. Rastall for their great kindness in identifying many of the 
specimens. 
