56 



The Naturalist. 



eastern wolds deposited in tliis vale during long ages is made up of 

 complex constituents. For our purpose Thorne Waste, as well as 

 Riccall Common, would, upon the map, come within this tract. 



3. — Most important in every way, I would have the area of our 

 county divided into three different areas, by means of surface shading 

 by fine parallel black or grey lines, each area limited by a contour 

 line. Each of these would indicate the three zones of altitude and 

 climate I have already described. Colour-washing would thus be left 

 for my fourth proposed divisioning. The upper zone is only, in York- 

 shire, small ; it covers little over 58 or 60 square miles. The surface 

 area of middle zone, including the moorlands of the hill swells and 

 spurs, is about 1200 square miles in extent. I would express this by 

 fine parallel line shading ; whilst the upper zone would be indicated 

 by a deeper shading, viz , the cross shading of " hatching." The 

 lower, or agrarion zone, I would have left unshaded. The three would 

 thus be distinguished, and it is easily done by an engraver, wooden 

 blocks being alone needed.- 



How would this apply in practice ? Well, I think — if a tyro found a 

 wheatfield, a table of explanations on map border, or on an accom- 

 panying map-key of descriptive character— w^hich I should be very 

 glad to write for the Union — would tell him, and by reiteration 

 impress it indelibly on his mind that he was in lower zone ; if he found 

 Fterls or Ruhus CJiamoemonts, that he must be in middle zone ; if Sedum 

 llhodiola, that he was surely in upper zone. Eut much more than this 

 would be suggested — and in time taught. 



4. — The map should show those lithological features I have already 

 indicated as influencing soil and distribution. Colour-washing should 

 here be used. Let the porous strata, chalk, oolites, permian tract, and 

 scar-limestone be washed-in in various shades of green (hinting at their 

 being most verdant botanically), the tracts of eu-geogenous rock 

 various shades of umber-brown to grey — the latter hue for the coal- 

 measure tract. The Lias strip, and Trias tract, drift-hid, can be 

 coloured pale yellow or salmon-hue, and also in this shade the sandy 

 tract of Holderness : these tracts holding lithologically intermediate 

 position. The vale of York, which I have already indicated as 

 important to be defined, will within its contour line coincide very 

 closely with the Triassic tract. Plant-species can then be recorded 

 systematically as occurring in zone ], 2, or 3; upon Holderness 

 sand (1), chalk (2), oolite (3), lias (4), trias sand (5), permian (6), 

 coal-measures (7), gritstone (8), Yoredale shales (9), mountain limestone 

 (10), and Silurian slate (11). 



