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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.



16 HERTFORDSHIRE

5. Watershed. Rivers.

In commencing this section it will be well to devote
a few lines to the proper meaning of the frequently mis-
understood 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.



WATERSHED RIVERS 17

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, even-
tually falls into the Cam.

The whole of the remaining rivers of the county be-
long 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

L. H. 2



18 HERTFORDSHIRE

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 Red-
bourn the Ver continues its course by way of Shafford
Mill, at which place it crosses the high road, to St Albans,



WATERSHED RIVERS 19

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 neigh-
bourhood 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.

2 2



20 HERTFORDSHIRE

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



22 HERTFORDSHIRE

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 Bunting-
ford), 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



WATERSHED RIVERS 23

way of Hammels, Standon, Barwick, Thundridge, to
cross the Ermine Street at Wade's Mill, and thence vid
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,



WATERSHED RIVERS 25

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 ;



26 HERTFORDSHIRE

thus he speaks of loose sand as a rock equally with a hard
substance like granite.

Rocks are of two kinds, (i) 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 pro-
duced 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.



GEOLOGY AND SOIL 27

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 sand-
stones, 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



'ERTIARY -
CONDARY -

RIMARY


NAMES or

SYSTEMS

' Recent & Pleistocene
' Pliocene
Eocene

Cretaceous

Jurassic

Triassic
'Permian

Carboniferous

Devonian
Silurian
Ordovician

Cambrian
Pre-Cambrian




CHARACTERS or ROCKS
sands, superficial deposits








clays and sands chiefly




chalk at top
sandstones, mud and clays below

shales, sandstones and
oolitic limestones

red sandstones and marls, gypsum and
salt

red sandstones & magnesian limestone

sandstones, shales and coals at top
sandstones in middle
limestone and shales below

red sandstones,
shales, slates and limestones

sandstones and shales
thin limestones

shales, slates,
sandstones and
thin limestones

slates and
sandstones

sandstones,
slates and
volcanic rocks





















GEOLOGY AND SOIL 29

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.

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 thick-
ness 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 super-
ficial 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.

As the greater portion of the subjacent rocks of the



30 HERTFORDSHIRE

county is formed by the Chalk, it will be convenient
to commence with this formation. The Chalk extends, or
"strikes," across all but the south-eastern portion of the
county in a broad belt, with a general south-westerly or
north-easterly direction, reaching on the northern side,
with a few exceptions, to the border of the county and
beyond, while to the southward its boundary runs ap-
proximately through Bushey, South Mims, Hertford, and
Bishop's Stortford. At Dunstable the Chalk forms what is
called an "escarpment," that is to say a high and somewhat
precipitous (although rounded) cliff overlooking the great
plain formed by the marls and clays of the underlying
strata. As in all true escarpments, the beds, or strata of
the Chalk, which are somewhat tilted by earth-movements
out of their originally horizontal plane, incline, or "dip"
away from the main face of the cliff, that is to say, towards
the south-east ; and this south-easterly dip of the Chalk,
apart from local interruptions and folds, continues to its
southerly boundary. Now since the Chalk is a porous
formation admirably fitted to collect and retain the rain-
water falling upon it, while it is underlain, as we shall
see shortly, by the impervious Gault Clay of the Bedford-
shire plain, and overlain along its southern boundary by
the equally impervious London Clay, it is obvious that
it will hold all the water thus collected, and that this
water will tend to run deep down in the rock in a south-
easterly direction. Hence the northern part of the Chalk
zone forms an almost perfect water-collecting area, which
can be tapped along the southern side of the county by
boring through the overlying London Clay.



GEOLOGY AND SOIL 31

The Chalk comprises several main divisions, of which
the. highest is known as the Upper Chalk, or the Chalk
with flints; this when fully developed being about
300 feet thick. It is a soft white limestone traversed by
nearly horizontal layers of black, white-coated flint, which
have originated by a process of " segregation " in the rock
subsequent to its deposition as ooze on the old sea-bed.
Usually these layers consist of irregular nodular masses;
but there is sometimes a continuous thin layer of scarcely
more than half-an-inch in thickness, locally known as
" chimney-flint." The south-easterly dip of the Chalk is
shown by the layers of flint to be not more, as a rule, than
three or four degrees. The Upper Chalk extends from
the summits of the hills as far down as Rickmansworth,
Watford, Hatfield, and Hertford, thus forming the bed-
rock of the greater portion of the county. By the wearing
away of the overlying Tertiary strata, a small cone, or
" inlier," of Chalk is exposed at Northaw.

Next comes a bed of about four feet thick known as
the Chalk-rock. It is a hard cream-coloured rock, con-
taining layers of green-coated nodules, is traversed by
numerous vertical joints, and rings to the stroke of the
hammer. Owing to its hardness, it resists the action of
the weather, and is therefore in evidence at or near the
summits of the hills, where it can be traced from close to
Berkhampstead Castle by Boxmoor and Apsley, and thence
to the south-west of Dunstable, Kensworth, the south of
Baldock, and so in a north-easterly direction to Lannock
Farm.

Below the Chalk-rock we come to the Middle Chalk,



32 HERTFORDSHIRE

or Chalk without flints, which may be so much as
350 feet in thickness, and rises in a rather steep slope
or " step " from the underlying beds to be next mentioned.
Flints are few and far between in the Middle Chalk,
which forms the western slope of the Downs at Royston,
as well as beyond the limits of the county at Luton, and




View on the Downs looking towards Wallington from
the Icknield Way

so on to the Chiltern Hills. Fossils are much more
numerous in the Middle than in the Upper Chalk. The
lowest bed of the former is the Melbourn Rock, a hard,
nodular band about 10 feet thick. Next comes the grey
and white Lower Chalk, from 65 to 90 feet thick, after
which we reach the Totternhoe Stone. Although only



GEOLOGY AND SOIL 33

six feet in thickness, this Totternhoe Stone, which forms
the escarpment of Royston Downs, is of importance as
having been largely employed in the construction of
churches and other buildings on the northern side of the
county. It is a sandy grey limestone, which used to be
largely quarried at Totternhoe, with special precautions
in drying. It can be traced from Tring by way of
Miswell, Marsworth, Pirton, and Radwell to Ashwell.

The Totternhoe Stone really forms the top of the
Chalk-marl, which is some 80 feet thick, and consists of
buff crumbling marly limestones. It forms a strip of low
ground at the base of the Chalk escarpment. At the
bottom of the Chalk occurs the so-called coprolite-bed,
which contains large quantities of phosphate nodules.
Forty years ago these beds were extensively worked
between Hitchin and Cambridge for the sake of the
nodules.

Only on the northern border of the county, between
Hitchin and Baldock, and then merely to a very small
extent, are any of the beds underlying the Chalk exposed.
These comprise, firstly the Upper Greensand, which is
either a sandy marl or a sandstone with green grains, and
secondly, a dark blue impervious clay known as the Gault.
These formations constitute the plain at the foot of the
Chalk hills in Bedfordshire, the scenery of which is very
similar to that of the London Clay plain in eastern
Hertfordshire and Middlesex.

It is important to add that, at a gradually increasing
depth as we proceed south, the Gault underlies the whole
of the Hertfordshire Chalk, and renders the latter such an

L. H. 3



34 HERTFORDSHIRE

excellent water-bearing formation. If the Gault be per-
forated we come upon the Lower Greensand, another
excellent water-bearing stratum, which comes to the
surface in the neighbourhood of Silsoe, in Bedfordshire.


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