NOTES «ON CHE 
TRAP-FLORA OF RENFREWSHIRE. 
By) GB.) Scorr) Ernror,. M.A., B-Se.,) FES: F.R:GS. 
(Read 4th September, 1903.) 
THE district which is referred to in these notes is that part of 
Renfrewshire and Ayrshire which lies in the triangle between the 
two G. & S.-W. Railway lines to Greenock and to Dalry respec- 
tively, and of which the base is a line up Noddsdale Glen. 
The rocks are composed mainly of porphyrite, melaphyre, etc., 
and are interbedded (according to the geological survey) in the 
shales, cement-stones, and grey sandstones of the Upper Old Red 
Sandstone. 
They are the result of a series of gigantic lava flows, originating 
somewhere in the north-west, and probably from an ancient 
volcano, now submerged, somewhere between Helensburgh and 
the Cloch lighthouse. They are most frequently exposed in a 
series of cliffs or escarpments, which run usually from east by 
north to west by south, but many are nearly due north and south. 
Intrusive felstones and porphyrites occur, and sometimes tuff 
replaces the porphyrite and melaphyre. 
Towards the east there are necks and dykes of Miocene basalt, 
but there are none in this district. 
Thus there were two periods of volcanic activity—one in the 
Upper Devonian and the other in Miocene times. 
These outbreaks are separated by an interval of time much 
greater than that which has elapsed between the last and our own 
days. 
The district has been much altered by ice action. It seems to 
have been the converging point of the northern or Highland and 
southern or Galloway ice. 
I think that many of the valleys, such as the parallel series of 
escarpments along the Lochar, as well as that from Carruth to 
Bridge-of-Weir along the Gryffe, and others, have been largely 
scooped or dug out by the ice-plough. 
A 
