BOTANY Overlying the London clay we have various formations consisting of sands and gravels. Amongst these are: (i) Bagshot beds, which constitute some of the higher and more picturesque tracts, as at High Beech, Brentwood, Warley, Billericay, Stock, Langdon Hill and Ray- leigh ; (2) the glacial gravels occurring at Quendon, at Clavering, at Harlow and at Roydon, along the Colne from Great Yeldham, Halstead, Gosfield, Great Bardfield, Thaxted, over the high grounds of Danbury, around Colchester, Brightlingsea and St. Osyth, in patches at Mersca Island and Tolleshunt, and at Tiptree Heath ; (3) valley gravel in the Thames valley. Boulder clay, another glacial drift formation, occupies a large portion of the surface of Essex. Bordering on our rivers we have large tracts of alluvium recently deposited, forming extensive marshlands. These marshlands near the sea and riverine estuaries are either covered at high tides, when they are known as saltings, or the sea water permeates them, when they may be described as brackish marshes. We have also on the edges of the sea coast considerable stretches of shingle and sand. The long stretches of sea wall protecting the coast have a characteristic though limited flora. It will therefore be evident that Essex has an abundant variety of soil, and is very pleasantly diversified with arable land and pasture, with woodlands, commons and well timbered hedgerows. It includes every species of soil from the most stubborn to the mildest loam. For our present purposes we may group the geological formations as follows : 1 . Chalk and Boulder Clay, which contains much chalk. 2. London Clay. 3. Gravels and Sands. 4. Alluvium. 5. Marine. Though chalk only comes to the surface over a small area in the county the chalk flora extends over a considerable portion of its surface, for the Essex boulder clay usually contains so much chalk that the chalk loving plants may always be met with upon this formation. It is upon this strata that the traveller's joy (Clematis Vitalba] flourishes more particularly. Both the green hellebore and the foetid hellebore also occur as natives upon the boulder clay. Berberis vu/garis is found at Saffron Walden on the chalk, also the common rockrose (Helianthemum uulgare), which plant also occurs at other stations. The hairy violet (Viola hirta) is common both upon the chalk and upon the boulder clay. The following chalk plants are included in our flora : the buck- thorn (Rhamnus c atharticus) , ladies' fingers (Anthyllis Vu Ineraria) , the wild liquorice (Astragalus glycypbyllos), the purple milk-vetch (A. hypo- glottis'), the dropwort (Spiraea Filipendula), the salad burnet (Poterium Sanguisorba], common hare's ear (Bupleurum rotundifoliuni) , dwarf thistle (Carduus acau/is), yellow-wort (Cblora perfoliata), autumnal gentian 35
