Oorrespondence—Dr. C. Callaway. 139 
The author described a series of beds overlying the normal Old Red 
Sandstone and underlying the normal Lower Limestone Shales in the 
above district. They differ from the ordinary Old Red Sandstone in 
two particulars:—(1) No fossils characteristic of this series have as 
yet been discovered in them. (2) The materials of which the Old 
Red of the neighbourhood is formed are well water-worn, while those 
composing the beds referred to are not so; they also contain calcareous 
material, and the author considered them to correspond, in time, with 
the Calciferous series of Scotland for the following reasons in addition 
to their stratigraphical position:—(1) with those of Berwickshire in the 
rapid succession and variation in the colour of beds; (2) the presence 
of certain Polyzoa and of Rhynchonella pleurodon in a limestone which 
succeeds them. The author also described a section in the Millstone 
Grit at the Morse railway-cutting. Here the Millstone Grit dips at 
about 40°; resting on it is a rose-coloured sandstone passing up into 
a pebble-bed dipping at 19°. The pebbles are vein-quartz and a 
quartzite like that of the Lickey. The Old Red Sandstone, Calciferous 
Sandstone, and Millstone Grit appeared to him to have derived their 
materials from a common source, viz. ancient granitic rocks. 
An Appendix by Dr. T. Wright described the organisms in specimens 
of the above-named limestone of Drybrook. Polyzoa are abundant, 
individuals being numerous, but species few. Rhabdomeson gracile 
and Fenestella tuberculata are abundant in one specimen, the other 
containing in addition Certopora similis. Fragments of a Crinoid, 
referred to Potertocrinus crassus, also abound. There are a few crushed 
shells of Rhynchonella pleurodon, and spines, possibly of a Productus. 
The organisms of a slab from the Bristol district were also described. 
This contains 2. gracile, with one or two other Polyzoa, and numerous 
Crinoid fragments. 
CORRESPONDENCE. 
es 
THE HIGHLAND PROBLEM. 
Sir,—Geologists are aware, from two short papers which I have 
communicated to the Geological Society, that I have been engaged 
for some years in the investigation of the relations between the 
Durness and Assynt Limestones and the great Eastern Gneiss.. ‘The 
difficulties surrounding the inquiry are so great that for the first two 
years I did not feel justified in announcing a definite conclusion on 
the main question. Two months of hard work last summer enabled 
me to fill in many important gaps in my evidence, and I am now in 
a position to make a definite announcement. My most important 
conclusions are the following :— 
1. The Eastern Gneiss has been brought over the Quartzo-dolo- 
mitic group by earth-movements subsequent to the deposition of the 
latter, and is of Archean age. 
2. The Quartzo-dolomitic series is frequently, at its junction with 
the Eastern Gneiss, folded back upon itself. 
3. The “ Upper Quartzite ” of Murchison is the “‘ Lower ” Quart- 
zite repeated by either faulting or folding, and the “‘ Upper Lime- 
