Part 2

Reference has already been made to the numerous open commons dotted over the chalk area of Hertfordshire. These appear to have been left as open spaces at the time the country was enclosed, owing to the sterility of their soil, which is unsuited for growing good crops of either corn or grass. Many of these commons, as in the neighbourhood of Harpenden, were enclosed some time previous to the battle of Waterloo, when corn in this country was so dear, and every available piece of land capable of growing wheat consequently of great value. It may be presumed that the commons with the best soil were selected for enclosure; but most of such enclosed commons produce inferior crops, partly, it may be, owing to the plan on which they are cultivated. Till twenty years ago or thereabouts all such commons in the writer’s own neighbourhood were divided into a number of parallel strips, separated by grass “baulks”; these strips representing the respective shares of the copyholders of the district, who had the right of grazing on the original common. The absence of hedges rendered it necessary that the same kind of crop should be grown each year on every plot. This made it not worth the while of the occupiers to spend money on high cultivation. Of late years many of these enclosed commons have either been built over, or come under a single ownership, thereby obliterating one more interesting page in the history of the county.

To the south of the Elstree range of chalk hills the scenery suddenly changes, and on emerging into Middlesex from the tunnel through these hills on the Midland Railway we enter an extensive grassy plain, characterised by its abundance of oak trees, the scarcity of elms, and the total absence of ash. Parts of this plain, which is continued through Middlesex to London, form the great grass-growing and hay-producing district of Eastern Hertfordshire.

A plain very similar in character to that south of Elstree is entered upon to the northward of Baldock, just after leaving the line of chalk hills, although the greater portion of this northern plain is situated in Cambridgeshire and Bedfordshire. When travelling northward from London by the Great Northern Railway, observant persons, after passing through the tunnels traversing the chalk hills north of Hitchin, cannot fail to notice the general flatness of the country as this great plain is entered. Although so like the southern plain in general appearance, this northern plain, as is noticed in the section on Geology, is composed of much older rocks.

The heights of some portions of the chalk area above mean sea-level are, for this part of England, considerable. Thus Great Offley Church is 554 feet, St Peter’s Church, St Albans, 402 feet, Stevenage 306 feet, Hitchin Church 216 feet, while a hill near Therfield attains the height of 525 feet. Hastoe Hill near Tring is 709 feet.

5. Watershed. Rivers.

In commencing this section it will be well to devote a few lines to the proper meaning of the frequently misunderstood term “watershed.” It means the line of water-division, or water-parting; that is to say the line along a range of hills from which the streams flow in one direction on one side, and in the opposite direction on the other. The ridge-tiles on a roof form an excellent illustration of a watershed.

Every local stream is separated from the one nearest to it by a watershed; while a river-system, such as that of the Thames, is separated by a much more important watershed from the other river-systems which take their origin near its source. Such river-systems, each enclosed by a single watershed which it shares with its neighbours, are known as drainage-areas, or catchment-basins.

Practically the whole of Hertfordshire lies in the Thames drainage-area. At first sight it would be natural to suppose that the summit of the line of chalk downs forming the continuation of the Chiltern Hills in the neighbourhood of Tring and continuing thence to Dunstable would constitute the watershed between two river-systems. But this is not the case, for the Thames cuts through the Chiltern Hills between Wallingford and Pangbourne, and thus receives the drainage of both the northern and the southern flanks of that range. The watershed formed by the continuation of the Chilterns in the Tring district is therefore one of second-rate importance.

On the other hand, in the chalk hills near Hitchin we have a watershed of first class, or primary rank, for it divides the Thames catchment-area from that of the Great or Bedfordshire Ouse, which flows into the North Sea miles away from the estuary of the Thames. Only four comparatively small streams flowing into the Ouse basin lie for part or the whole of their course within the limits of the county. The first of these is the Pirre, or Purwell, a small brook which rises in the parish of Ippolits, and, after passing Much Wymondley, flows into the Hiz near Ickleford. The Hiz itself rises in a spring at Wellhead, a short distance southward of Hitchin (formerly also called Hiz), and after receiving the Purwell, flows to Ickleford, where it leaves the county, being joined in Bedfordshire by the Ivel, which rises not far from Baldock, passing Biggleswade to join the Ouse. Below Biggleswade it flows through Tempsford, where it unites with the Ouse. The last of the four streams belonging to the Ouse system is the Rhee (a Saxon term signifying a water-course or river), which springs strongly from the chalk a short distance west of Ashwell, and after passing Accrington Bridge and crossing the Ermine Street, eventually falls into the Cam.

The whole of the remaining rivers of the county belong to the Thames catchment-area. With the exception of the Thame, to be mentioned immediately in a separate paragraph, these form two main systems, namely that of the Colne draining the western and that of the Lea the northern and eastern part of the county; the watershed between these two systems running in a north-westerly and south-easterly direction between St Albans and Hatfield, and thence to the north of Chipping Barnet.

The Thame is almost entirely a Buckinghamshire river, but it rises in our county and runs on the north side of the great watershed formed by the continuation of the Chiltern Hills; this watershed constituting a broad, nearly waterless belt separating the catchment-area of the upper Thame from that of the Lea. The Thame itself springs from three heads in the parish of Tring; the first of these rising near the vicarage, the second at a spot called Dundell, and the third in a spring known as Bulbourne. The three become united at New Mill, whence, after passing through Puttenham, the Thame flows by Aylesbury, in Buckinghamshire, and from there continues its course till it eventually joins the Thames near the village of Dorchester, a considerable distance below Oxford.

Of the tributaries of the Colne system, the most important is the Ver (or Verlume), which rises some distance to the east of Cheverell’s Green, on the Watling Street, and passes through the village of Flamstead, and thence near the line of the high road to Redbourn, where it is joined by an intermittent stream, or “bourne,” known as the Wenmer, or Womer. The latter crosses the road from Harpenden to Redbourn at the foot of a steep descent; and in the old days its appearance as a running stream was believed to forbode a death, or “some extremity of dangerous import.” From Redbourn the Ver continues its course by way of Shafford Mill, at which place it crosses the high road, to St Albans, where it passes between the present city and the ruined walls of ancient Verulam, to which latter it is generally believed to have given its name. Thence its course is continued through the old nunnery of Sopwell (of which it supplied the extensive fish-ponds), and from that point it flows through Park Street to join the Colne near Colney Street; the latter stream giving the name to the united rivers, although the Ver is considerably the larger of the two constituents. The Colne itself rises in the neighbourhood of Tittenhanger, between St Albans and Hatfield, and passes through London Colney on its way to join the Ver. Near Watford the Colne receives an important tributary in the shape of the Gade, which issues from the chalk in the meadows of Great Gaddesden (to which and Gadebridge it gives the name), and after passing through Hemel Hempstead and Nash Mills, is joined at Two Waters by the Bulbourne. The latter rises at Tring very close to the Bulbourne source of the Thame (the watershed being here very narrow), and runs by way of the Frith, Dagnalls, Aldbury Meads, Dudswell Bottom, and North Church to the north-east side of Berkhampstead, where its volume is increased by two important springs, and thence to Two Waters. There is also an intermittent stream known as the Hertfordshire Bourne, which, when running, flows into the Bulbourne about halfway between Berkhampstead and Boxmoor. It is reported--and apparently correctly--to flow on the average once in every seven years; the point from which it flows may be higher up or lower down in the valley according to the amount of water discharged.

Below Two Waters the Gade (as the united stream is now called) passes through Kings Langley, Hunton Bridge, and Cassiobury Park to join the Colne between that park and Watford. After skirting the north side of Moor Park immediately below the last-named town, the Colne receives the Chess (giving the name to Chesham, in Buckinghamshire), which passes through Sarratt in our own county. The Colne then reaches Rickmansworth, where it forms the boundary between Buckinghamshire and Middlesex, and thence flowing by way of Uxbridge and Colnbrook, discharges itself into the Thames above Staines, after a course of about thirty-five miles.

We pass next to the basin of the Lea or Luy, the Logodunum or Logrodunum of the ancient Britons, and the largest river in the county. The Lea itself takes origin in a marsh at Leagrave, or Luigrave, a little north of Luton (= Lea-town), in Bedfordshire, and after passing through Luton Hoo, in that county, where it is expanded into a large artificial lake, enters Hertfordshire at East Hyde, in the valley north of Harpenden, and flows thence by way of Wheathampstead and Brocket (where it again expands into another artificial lake) to Hatfield, whence its course is continued by way of Essendon and the north side of Bayfordbury Park to Hertford. Just before entering the county town the Lea receives the Mimram, or Marran, which rises in the parish of Kings Walden, to the north-west of the Bury, and flows to the eastward of Kimpton Hoo, and thence by way of Codicote, Welwyn, Digswell (with added supplies from local springs), Tewin Water, and Hertingfordbury to its junction with the Lea close to Hertford. In the upper part of its course the Mimram receives the small brook known as the Kime, from which Kimpton and Kimpton Hoo take their names.

In Hertford the Lea is divided into two channels, one of which runs through the eastern portion of the town to cross Great Hertham common, while the other, which is navigable, passes along the western side to join its fellow at the aforesaid common.

At about one-third the distance between Hertford and Ware the Lea is largely augmented by the waters of the Beane (Benefician) and the Rib, which join close to their union with the main river. The Beane rises from a ditch in the parish of Ardeley (between Stevenage and Buntingford), and thence flows in a southward direction by way of Walkern, Aston, Frogmore, Watton, and Stapleford, passing on its way through Woodhall Park, at the entrance to which it is reinforced by several strong springs. Between Watton and Stapleford it also receives a small brook flowing from Bragbury End.

Starting in an easterly direction from Ardeley or Walkern, we shall cross the low watershed dividing the valley of the Beane from that of the Rib; which latter takes its rise near Reed, and after crossing the Ermine Street at the south end of Buntingford, flows by way of West Mill and New Bridge to Braughing, where it is joined by the Quin, which issues from a spring at Barkway, and passing by Hormead and Quinbury (to which it lends its name), reaches Braughing Priory. Below Braughing the Rib, as it is now called, flows by way of Hammels, Standon, Barwick, Thundridge, to cross the Ermine Street at Wade’s Mill, and thence _viâ_ Ware Westmill and Ware Park to join the Lea with the Beane.

From Luton to Hatfield the course of the Lea pursues a generally south-easterly direction; at Hatfield it becomes for a short distance due east, and then trends to the north-east through Hertford to Ware. Here it takes a sudden bend, so that the remainder of its course through the county and the adjacent portion of Essex is almost due south. A direct line from Luton to the Lea near Waltham Abbey measures about 40 miles; but, owing to its great north-easterly bend, the course of the Lea between these two points is something like 45 miles.

The last two rivers on our list are the Ash and the Stort, both of which in the upper part of their courses run from north to south nearly parallel with the Beane and the Quin. The Ash rises near Brent Pelham and thence flowing by Much Hadham and through the parish of Widford, falls into the Lea above Stanstead Abbots. The Stort, which is the most easterly tributary of the Lea in the county, is of Essex origin, taking its rise at the very border of the county, near Meesdon, and entering it again close to Bishop’s Stortford. Some distance above Stortford it receives one tributary from the Essex and a second from the Hertfordshire side, the latter forming for a short distance the boundary between the two counties. At Stortford the Stort is wholly within Hertfordshire, but a little below the town it forms the county boundary for a considerable distance, passing by way of Sawbridgeworth on the Hertfordshire, and Harlow on the Essex side, to join the Lea a short distance below the Rye House. From this point and Hoddesdon nearly to Waltham Abbey the Lea forms the boundary between Hertfordshire and Essex, finally leaving the former county near Waltham. The river now constitutes the line of division between Middlesex and Essex, finally joining the Thames below Bow Bridge, at Barking, after a course of 45 miles.

Here may conveniently be mentioned the celebrated Chadwell spring, near Hertford, which after supplying London with a large amount of water by way of the New River (of which more in a later chapter) for three hundred years, failed temporarily in 1897, so that water began to flow into, instead of out of its basin. Previous to this failure the amount of water discharged daily by the Chadwell spring was estimated at not less than 2,600,000 gallons. In addition to the temporary failure of Chadwell, a spring in Woolmers Park, near Hertford, has of late years completely dried up; both these failures being attributed mainly, if not entirely, to the tapping of the Hertfordshire water-supply by the deep borings in London.

6. Geology and Soil.

By Geology we mean the study of the rocks, and we must at the outset explain that the term _rock_ is used by the geologist without any reference to the hardness or compactness of the material to which the name is applied; thus he speaks of loose sand as a rock equally with a hard substance like granite.

Rocks are of two kinds, (1) those laid down mostly under water, (2) those due to the action of fire.

The first kind may be compared to sheets of paper one over the other. These sheets are called _beds_, and such beds are usually formed of sand (often containing pebbles), mud or clay, and limestone or mixtures of these materials. They are laid down as flat or nearly flat sheets, but may afterwards be tilted as the result of movement of the earth’s crust, just as you may tilt sheets of paper, folding them into arches and troughs, by pressing them at either end. Again, we may find the tops of the folds so produced worn away as the result of the wearing action of rivers, glaciers, and sea-waves upon them, as you might cut off the tops of the folds of the paper with a pair of shears. This has happened with the ancient beds forming parts of the earth’s crust, and we therefore often find them tilted, with the upper parts removed.

The other kinds of rocks are known as igneous rocks, which have been molten under the action of heat and become solid on cooling. When in the molten state they have been poured out at the surface as the lava of volcanoes, or have been forced into other rocks and cooled in the cracks and other places of weakness. Much material is also thrown out of volcanoes as volcanic ash and dust, and is piled up on the sides of the volcano. Such ashy material may be arranged in beds, so that it partakes to some extent of the qualities of the two great rock groups.

The relations of such beds are of great importance to geologists, for by means of these beds we can classify the rocks according to age. If we take two sheets of paper, and lay one on the top of the other on a table, the upper one has been laid down after the other. Similarly with two beds, the upper is also the newer, and the newer will remain on the top after earth-movements, save in very exceptional cases which need not be regarded here, and for general purposes we may look upon any bed or set of beds resting on any other in our own country as being the newer bed or set.

The movements which affect beds may occur at different times. One set of beds may be laid down flat, then thrown into folds by movement, the tops of the beds worn off, and another set of beds laid down upon the worn surface of the older beds, the edges of which will abut against the oldest of the new set of flatly deposited beds, which latter may in turn undergo disturbance and renewal of their upper portions.

Again, after the formation of the beds many changes may occur in them. They may become hardened, pebble-beds being changed into conglomerates, sands into sandstones, muds and clays into mudstones and shales, soft deposits of lime into limestone, and loose volcanic ashes into exceedingly hard rocks. They may also become cracked, and the cracks are often very regular, running in two directions at right angles one to the other. Such cracks are known as _joints_, and the joints are very important in affecting the physical geography of a district. Then, as the result of great pressure applied sideways, the rocks may be so changed that they can be split into thin slabs, which usually, though not necessarily, split along planes standing at high angles to the horizontal. Rocks affected in this way are known as _slates_.

NAMES OF SYSTEMS CHARACTERS OF ROCKS

{ Recent & Pleistocene+------+ { Pliocene +------+ sands, superficial deposits TERTIARY { Eocene +------+ { | | clays and sands chiefly +------+ { Cretaceous | | chalk at top { | | sandstones, mud and clays below { +------+ SECONDARY{ Jurassic | | shales, sandstones and { | | oolitic limestones { +------+ { Triassic | | red sandstones and marls, { | | gypsum and salt +------+ { Permian | | red sandstones & magnesian { +------+ limestone { | | { | | sandstones, shales and coals { Carboniferous | | at top { | | sandstones in middle { | | limestone and shales below { +------+ { | | { Devonian | | red sandstones, { | | shales, slates and limestones { +------+ { | | { Silurian | | sandstones and shales { | | thin limestones PRIMARY { +------+ { | | shales, slates, { Ordovician | | sandstones and { | | thin limestones { | | { +------+ { | | { Cambrian | | slates and { | | sandstones { | | { | | { +------+ { | | { | | { | | sandstones, { Pre-Cambrian | | slates and { | | volcanic rocks { +------+

If we could flatten out all the beds of England, and arrange them one over the other and bore a shaft through them, we should see them on the sides of the shaft, the newest appearing at the top and the oldest at the bottom, as shown in the figure. Such a shaft would have a depth of between 10,000 and 20,000 feet. The strata are divided into three great groups called Primary or Palaeozoic, Secondary or Mesozoic, and Tertiary or Cainozoic, and the lowest of the Primary rocks are the oldest rocks of Britain, which form as it were the foundation stones on which the other rocks rest. These may be spoken of as the Pre-Cambrian rocks. The three great groups are divided into minor divisions known as systems. The names of these systems are arranged in order in the table with a very rough indication of their relative importance, though the divisions above the Eocene have their thickness exaggerated, as otherwise they would hardly show in the figure. On the right hand side, the general characters of the rocks of each system are stated.

With these preliminary remarks we may now proceed to a brief account of the geology of the county.

In Hertfordshire, apart from the soil and the superficial accumulations of gravel, sand, and clay, only the lower beds or strata of the Tertiary and the uppermost formations of the Secondary period are represented.