342 C. LAPW0RTH OK THE MOEEAT SERIES. 



bands everywhere emerge from below the surrounding greywackes 

 in anticlinal forms, as in the Moffat district. If this be the case, 

 all the greywackes that floor the Uplands from St. Abb's Head to 

 the Mull of Galloway necessarily belong to one and the same great 

 arenaceous group, which must be of newer date than the Moffat 

 Series, and therefore, generally speaking, of Llandovery age. 



This conclusion is in exact accordance with what is already 

 known of the fauna of the arenaceous deposits to the north of the 

 Moffat area. Though the facts are somewhat complicated by the 

 replacement in the Girvan area of the dark beds of the Moffat 

 Series by limestones and breccias containing Bala and even Llandeilo 

 fossils, yet in the intervening districts of Peebles, Leadhills, and 

 Moniave, where the Hartfell and Glenkiln divisions are still recog- 

 nizable, it has been clearly shown by the officers of the Geological 

 Survey of Scotland that the conglomerates nearly at the base of the 

 greywacke group are often crowded with fossils (Corals, Crustacea, 

 and Brachiopoda) of well-known Llandovery types. 



To the south of the Moffat district this agreement is even more 

 striking. The great greywacke group to the south of the Ettrick 

 was proved by us, in the earlier portion of this paper, to repose 

 upon the Birkhill (Lower Llandovery) Shales of the Moffat Series. 

 After undergoing innumerable repetitions among the desolate wilds 

 of Eskdalemuir, in the contorted and inverted attitudes of their 

 equivalents in the Moffat area, the beds of this great group gradually 

 roll over to the southward, and pass up steadily, by a conformable 

 and gradual lithological and organic transition, into the Riccarton 

 Beds of Kirkcudbright, Mosspaul, and the Slitrig, which are ac- 

 knowledged on all hands to be the representatives of the Wenlock 

 Shale of Siluria. 



(e) Geologists have long been aware of the presence of a chain of 

 enormous volcanos in the Lake-district of the north of England, 

 which vomited forth mountain-masses of lava and ashes throughout 

 the greater portion of the Llandeilo epoch. Those who accepted the 

 theory of the Llandeilo age of the dark shales and greywackes of 

 the south of Scotland, and attempted to correlate them with their 

 supposed equivalents on the south of the Solway, have frequently 

 expressed their astonishment that these Scottish deposits, which 

 must have been laid down in a sea in some places less than 30 miles 

 distant from the volcanic area of the Lake-district, yet showed no 

 trace whatever of contemporaneous igneous action, whether in the 

 form of trap- dyke, lava-flow, or bed of volcanic ash. 



Our conclusion that the oldest beds of the south of Scotland (the 

 Glenkiln Shales) are in reality the equivalents of the highest 

 Llandeilo rocks, read in conjunction with the recent determination 

 of the absence of the highest Llandeilos in the Lake-district owing 

 to the break between the Borrowdale and Coniston groups, as 

 worked out by Mr. Aveline and the officers of the Geological Survey, 

 rids us at once of this vital difficulty. It is not only possible, but 

 indeed highly probable, that the volcanic series of Cumberland are 

 represented by similar rocks in the south of Scotland. They are, 



