ORNITHOLOGICAL NOTES. 



353 



to the manner in which the Tertiary dykes range across the country 

 without any respect to strike, faults, or otlier geological accidents in 

 the rocks traversed. In this they differ from many other sets of 

 dykes, which have a bearing often clearly dependent on the lie of 

 the strata they intersect. For instance, the post-Carboniferous but 

 pre-Permian dykes of the ]Menai Straits run at right angles to the 

 strike of the Carboniferous rocks, and often fill dip-faults; and the 

 same is true of dykes of like age in some other districts, including 

 perhaps the Isle of Man. Dr. Geikie, however, considers some of 

 the Isle of Man dykes as belonging to the great Tertiary outburst ; 

 while yir. Clifton AVard, again, believed some in the south of the 

 island to be connected with a volcanic outbreak during the Car- 

 boniferous period. Here is a problem for the Manx geologists to 

 solve. 



Finally, if it be permitted to theorise in a subject so little known, 

 we may perhaps conveniently group igneous dykes under three 

 heads, arranged in order of increasing geological importance : — 

 firstly, those in connexion with volcanic necks or plutonic bosses, 

 commonly presenting a rough radial arrangement about their source ; 

 secondly, those injected during or closely subsequent to movements 

 of folding, etc., in the strata, sometimes showing a tendency to run 

 approximately parallel, or more frequently perpendicular, to the axes 

 of movement, and ofien along lines of faulting ; and thirdly, those 

 belonging to more extensive geological operations (fissure-eruptions, 

 etc.), these dykes sometimes presenting a general parallelism, which 

 may be part of a larger radial disposition, and being to a great 

 extent independent of any mmor geological features of the rocks 

 through which they break. 



jVO TES— ORNITHOL OGY. 



Roug'h-legg'ed Buzzard at Meanwood, Leeds. — When passing along 

 the Meanwood Road, on November 6th, just within Leeds borough boundary, niy 

 attention was called to a large bird in a stubble-field (apparently feeding), which 

 my informant described as a Sea-Gull, When I endeavoured to approach it, it 

 rose and flew slowly past me, alighting finally in a low tree. It was soon after- 

 wards shot and proved to be a fine specimen of the Rough-legged Buzzard 

 {Archibiiteo /a<^^flpus). The \md was in excellent plumage, and measured 56 in. 

 from tip to tip of wings.— H. Kni(;ht Horsfield. 



Whitby Bird-notes. — The following extracts from my ornithological notes for 

 this month may be interesting: — 



November.— Young Golden-eye Duck ( Clangiila glmicion) shot in Whitby Harbour. 

 ,, 3. — Immature specimen of Eider Duck [So>/iateria luollissivia) killed in 

 Whitby Harbour. 



9.— Another immature specimen of Eider Duck shot in the harbour of 

 Whitby. 



,, 10. — Large Black -backed (iull (Lariis mariniis) shot in the harbour. — 

 Thomas Siei'HENSON, Whitby, 22nd November, 1888. 



Dec. 1888. 



