Nature

Geology

The geology of the Barleywolds is roughly: chalk hills in the north, and chalky boulder clay in the south. However, the underlying bedrock is all chalk, except in the far south where there is some underlying clay, but there is overlying boulder clay over most of the Barleywolds except the far north, where chalk is at the surface. The chalk formed from the microscopic shells of phytoplankton in shallow seas, roughly 100 million years ago. This was compressed deep in the earth, then raised up to form a band of chalk running diagonally across England. Around 450,000 years ago, during one of the deepest ice ages, an ice sheet forced its way south, across the top of this band of chalk, and deposited “boulder clay” on the other side. But the rough passage over the chalk ridge, made this clay seriously chalky - which created good soils..

Chalk exposed south of Royston

Landscape

The topography of the Barleywolds is gently-rolling, low hills cut by valleys running south from the chalk 'highlands' in the north. Between the valleys are clay uplands which in some places forms plateaus. The chalk is relatively resistant to rain weathering, so forms hills, but chalk's soft nature means it erodes over time, so the hills are low and rolling - in contrast to hard rock, which gives high and spiky hills. The passage of the ice sheets over the hills also smoothed them, and the rivers draining the ice sheets carved the valleys, running south. The soils of the north, where the chalk is close to the surface, are reasonably well drained, which means they are easy to plough - relative to clay soils that hold water and are not easily ploughed. However, the chalk is full of flints, which may need to be removed from the soil, but can them be used for building. When these chalks hills are used for pasture, they result in an open, green, rippling blanket, as on Therfield Heath. The valleys of the Barleywolds were cleared of forest for crops early, while the higher land was left as forest until later, but used for wood, pigs and hunting. The lords of the manors enclosed some forest as Parks for hunting, for example at Bennington and Weston. The settlement pattern of these high woodland areas typically results in dispersed settlements of individual farms or a few houses, surrounded by a patchwork of woods, parks, fields and meandering lanes. Whereas the settlement pattern of the valleys and chalk escarpment is typically nucleated villages around common greens, and surrounded by large fields, which used to be the common fields.

The Hertfordshire Spike, David Lawrence Art

The chalk escarpent of the Barleywolds at Weston, Clothall, Therfield, Heydon and Barkway. Note: i) the gently rolling hills, characteristic of chalk, ii) the whiteness of the unploughed fields, characteristic of chalk, iii) the relative emptiness of the arable landscape, characteristic of the Barleywolds,and iv) most of the landscape is arable fields, but there is a patchwork of woods, chalk meadows, and hedgerows.

http://landscape-east.org.uk/lct/chalk-hills-and-scarps

Chalk grasslands

Chalk grasslands are associated with softly rolling pastoral landscapes, and can be found on the north slopes of the Barleywolds, such as at Therfield Heath. The short, aromatic turf is flower-rich and humming with insects in the summer, including rare and beautiful butterflies. Scrub includes lime-loving species such as guelder rose, dogwood and burnet rose, in addition to hawthorn and blackthorn, and occasionally juniper. The scrubby grassland margin may host common calamint and the great green bush-cricket. Quaking grass, meadow oat-grass, wild thyme, dropwort, bird’s-foot-trefoil and salad burnet are common on chalk. Through the summer, look for a succession of orchids including early purple, common spotted, pyramidal, fragrant, bee, burnt, greater butterfly, frog and musk orchids and autumn lady’s-tresses. Rarer are pasqueflower, round-headed rampion and early gentian. Bugs include: bees, ants, hoverflies, beetles and grasshoppers (including rufous and striped-winged).

Common spotted orchid (and cowslips)

Chalk rivers

Chalk streams are a globally rare habitat, important for wildlife such as water vole, brown trout, grayling and bullhead. They are clearer and more uniform in temperature than other rivers. However, they rely on winter rainfall to maintain summer flows. Plants typical of these streams include: Blunt-fruited water-starwort, Lesser water-parsnip, Stream water crowfoot, Brook water crowfoot, and whorl-grass. The Chalk rivers/streams draining south from the Barleywolds are (from west to east): the Beane, Rib, Quin, Ash and Stort. For wildlife and conservation on these rivers see: https://www.riverleacatchment.org.uk

On the north side of the Barleywolds, chalk streams start from springs, for example at Fowlmere Nature Reserve, with strickingly clear water.

Stream water crowfoot in a clear chalk stream

Pasqueflower

Rare flowers found on the Barleywolds include the Pasqueflower, which flowers in abundance on Therfield Heath in March/April.

Red deer

Red deer, roe deer and fallow deer are found in the Barleywolds, sometimes in very large herds, usually on the quieter uplands, near woods. White fallow deer are quite common.

Chalkhill Blue

Chalk butterflies include: Chalkhill, Small and Adonis blues, silver-spotted skipper, Duke of Burgundy, marsh fritillary and Lulworth skipper, dingy skipper, brown argus, marbled white and meadow brown.

The Red Kite

Red Kites are a glorious sight and sound when soaring, and are now ubiquitous in the Barleywolds. But Kites were hunted and poisoned to extinction in the England during the 18th and 19th century, because of their reputation as scavengers. They were reintroduced from Europe between 1989 and 1993, including 90 birds released in the Chilterns, from where birds spread east to the Barleywolds. They pair bond for life and can live for up to 29 years. Egg laying starts late March. Eggs hatch after 32 days. Diet consists mainly of dead sheep, pigs, and roadkill, plus earthworms, birds and small mammals. Distributed across Europe, particularly Germany. Kites in Northern Europe used to migrate south for winter, but now generally stay put. Kites have a piercing unworldly cry that echoes, making the sound difficult to locate. Distinguished from the Common Buzzard by their V-shaped tail, whereas the buzzard has a fan shaped tail. And the colour of Kites is rusty brown with a hint of red, whereas buzzards are chocolate brown flecked with white (or white flecked with brown from below).

Red kite

Buzzard

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