Prof. C. Lapworth—Ballantrae Rocks of South Scotland. 67 
can only be harmonized upon the lines here laid down, it must be 
frankly admitted that, in spite of all that has been already accom- 
plished, our knowledge of these strata is still in its infancy. We 
have so recently become aware of the proper methods of attacking 
the many geological problems they present for solution, that the 
most interesting and complicated part of the work yet remains to 
be done; and those geological students who have made themselves 
familiar with the new developments of our knowledge of the older 
rock-formations will find this South Scottish region a fruitful field 
for original research. My own intermittent labours for the last 
twenty years in this great plateau (which covers an area of at least 
5000 square miles) have been only sufficient to permit of my working 
out in detail the sequence in the two contracted areas of Moffat 
and Girvan, and of studying in much less minuteness a sufficiency 
of the test districts elsewhere to enable me to feel assured of the 
general truth of the views here developed. It remains for others, 
and especially for local geologists, to verify and to apply these 
views to the detailed mapping of the Uplands generally. 
In the paleontological part of this work the Graptolites must, of 
necessity, play the chief rdle, for they are almost the only fossils 
met with in the strata of this wide region. But the minor strati- 
graphical conclusions to which those fossils point ought not to be 
overstrained, but should be tested and re-tested upon every available 
opportunity. We cannot expect to recognize from end to end of 
the Uplands all the minuter “zones” of Moffat, Girvan, Skellgill or 
Scania; but we ought certainly to be able to identify by their means 
all the major stratigraphic subdivisions. Nothing more can be 
claimed for the Graptolites than that which is claimed by all 
geologists for the corresponding species of Trilobites or Ammonites. 
Hach formation has its characteristic Graptolitic species and varieties, 
and each species has a certain fairly known vertical range in the 
detailed sequence of the Lower Paleeozoic rocks ;' while the invari- 
able association of special forms in beds of corresponding systematic 
position affords a presumptive paleontological index of the true sys- 
tematic place of strata marked by the same forms elsewhere. 
With this we must rest content; but even here I hold we have 
sufficient paleontological criteria, when checked and aided by all 
the available local stratigraphical evidences, to enable us to map out, 
in time, the Lower Paleozoic rocks of the Uplands in all their 
main geological subdivisions. 
The known restriction of the entire family of the Monograptide 
to Silurian strata, and its absence from Ordovician rocks, affords us 
the means of determining the outcrop of the Upland boundary-line 
between the Ordovician and Silurian deposits; and the laying down 
of this line will give us the first useful geological map of the region. 
Next must follow the tracing of the less important divisional lines 
at the bases of the Glenkiln (Upper Llandeilo) and Hartfell (Caradoc) 
Groups in the Ordovician, and those at the summits of the Birkhill 
(Llandovery) and Gala (Tarannon) Series of the Silurian. Not 
1 Lapworth, Geol. Dist. Rhabdophora, Tullberg, Skanes Graptolither, etc. 
