495 
of Edinburgh , Session 1868-69. 
gow, Fife, Kinross, Peebles, Selkirk, Lanark, Ayr, and Kirkcud- 
bright. In addition to these maps on the scale of one inch to a 
mile, thirty-six sheets of the coal-field maps, on the scale of six 
inches to a mile, have been published, including the coal-fields of 
Mid-Lothian, East Lothian, Fife, and Ayrshire. A considerable 
number more, now in the hands of the engraver, embrace the 
northern half of the Ayrshire coal-field, with part of the great 
coal-basin of the Clyde. In addition to the maps, sheets of hori- 
zontal sections are published, to explain the structure of the 
country, and also vertical sections, to illustrate the strata of the 
different coal-fields. Descriptive memoirs are likewise issued along 
with the maps, giving the detailed evidence on which the geological 
lines have been drawn, list of fossils, and all important information 
obtained in the course of the survey.* 
I shall now proceed to indicate some of the more important 
scientific results which have been obtained by the Geological 
Survey of Scotland during the four years which have elapsed since 
I last addressed the Society upon this subject. Beginning with the 
oldest rocks we have examined, I may remark that the complicated 
Silurian geology of Garrick has been mapped, and a large suite of 
fossils collected from that district. From the south-west of Ayr- 
shire the lower Silurian rocks have been traced across Nithsdale and 
Clydesdale into the valley of the Tweed. In the prosecution of 
the work, within the last few months an important discovery has 
been made by one of the younger members of the Survey, Mr K. L. 
Jack — viz., the occurrence of a bed of fossiliferous conglomerate, 
which has been traced for about five miles among tbe Leadhills. 
The fossils have not yet been examined, but there seems much 
probability that this bed will prove to be a prolongation of the well- 
known Wrae limestone, and thus define the age of the strata of the 
Leadhill district. A large area of Old Red Sandstone has now been 
examined, including the whole region between St Abb’s Head and 
* In the coarse of his remarks, the speaker pointed to a large map of the 
southern half of Scotland, on the scale of one inch to a mile, on which all 
the area yet surveyed hy the Geological Survey was coloured. There were 
likewise suspended on the wall specimens of the maps of the coal-fields of 
Fife and Ayrshire, on the scale of six inches to a mile ; specimens of the 
horizontal and vertical sections, and of the duplicate manuscript maps pre- 
served in the office of the Survey. 
VOL. Vi. 3 T 
