Revieus — Macnrn'r*s Geology of the Grampians. 81 



provided. The structure there represented is on a large scale a gentle 

 anticline of bedding. 



In a short chapter concluding the first volume the author returns 

 to a description of the narrow helt of cherts and black shales which 

 crop out along the Highland border. Although the exact relation of 

 these supposed Arenig rocks is left as an open question, he can find 

 no justification for sejiarating these rocks, at any rate as seen in 

 Perthshire, from the crystalline schists of the Highlands. 



The second volume opens with an interesting description of the 

 Lower Old Red Sandstone of Strathmore, the stratigraphy and 

 structure being written up mainly from the papers of Jack & 

 Etheridge and Du Toit. The plant and fish remains are also 

 described and illustrated. The Upper Old Ked Sandstone, which 

 rests Avith a violent unconformity on the Lower, occurs only in small 

 patches, sometimes preserved between trough-faults. The interesting 

 outlier of Lower Carboniferous rocks near Dron, proving the former 

 extension of the Carboniferous rocks north of the Ochil Hills, is also 

 noticed. 



In the following chapter the author attempts to prove that the Old 

 Red Sandstone was laid down in the sea. In this few geologists will 

 agree with him, though it be not difficult to find objections to the 

 generally accepted lacustrine theory. His chief argument is that if 

 the Lower Old Red Sandstone were to be replaced in the position it 

 occupied before the faulting along the Highland border took place, it 

 would pass completely over the Highland hills even though they 

 were four times their present height. Further, that the position of 

 outlying masses upon the dividing ridge makes it difficult to believe 

 that the lake basins were separate and yet contemporaneous. The 

 argument that the 'Orcadian' and 'Caledonian' cannot be con- 

 temporaneous, because the former does not contain a volcanic horizon, 

 is one which is difficult to follow. Other reasons given are, to say 

 the least, curious. Thus, nothing will persuade the author that the 

 Lome basin is other than an outlier, because the boulders in its 

 conglomerates are so large as to preclude the possibility of its being 

 formed in a basin only a few miles wide (p. 29). The chemical 

 difficulty in the precipitation of red oxides of iron in the ocean is 

 ignored, and the attempt to bolster up his theory by an appeal to the 

 palteontological evidence is altogether unconvincing. After the study 

 which terrestrial accumulations have received in recent years, those 

 geologists who find difficulties in accepting the lacustrine theory 

 will be ready to admit that much of the Old Red Sandstone may 

 have been formed under certain continental conditions, but few, if 

 any, will find satisfaction in the marine theory. 



Chapter x contains a description of the unfoliated plutonic rocks 

 and dykes intruded into the Highland schists. These include the 

 well-known igneous complex of Garabal Hill, the plutonic rocks of 

 Carn Chois, and a small intrusion situated on the eastern shore of 

 Loch Tay. Short notices follow on various sills and dykes of quartz- 

 porphyry, felsite, and lamprophyre. 



The following chapter treats of the volcanic rocks of Lower Old 

 Red Sandstone age, which form the Sidlaw and Ochil Hills. These 



DECADE V. — VOL. VI. — NO. II. 6 



