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Excursion to Hertford and Ware
519 EXCURSION TO HERTFORD AND WARE. SA.TURDA.Y, 22ND JUNB,
1878.
Di1'ectors-The President, Professor MORRIS, F.G.S., and JOHN HOl'KINBON, Esq., F.L.S., F.G.S., Hon. Sec. Watford Nat. Hist. Soc. (RepC»'t by Mr. HOPKINSON.)
The northern edge of the London Tertiary Basin passes for a considerable portion of its course through the county of Hertford, and within the last few years several places along this line of outcrop have been visited by the Association, in conjunction with the Watford Natural History Society and Hertfordshire Field Club. On this occasion the neighbourhood of the county town was selected for investigation, and Members of the two Societies met at Hertford Station at half-past ten, the local Field Club forming by far the larger party. The first place visited was Hertford Castle, near which there are still standing, completely overgrown with ivy, the ruins of a much older structure, once an important fortress, supposed to have been built by King Alfred. From the Castle the route lay through the churchyard, famed for its fine avenue of chestnuts, 200 years old, and thence by permission through Ball's Park, the seat of the Marquis Townsend, to Mr. Lines' brickfield, between Rush Green and Little Amwell, the first point of geological interest. Before, however, the brickfields were visited, a chalk-pit near afforded Professor Morris the text for an interesting address, in the course of which he showed that the flints immediately above the Chalk were of a different colour to those in the Chalk, some chemical change having given them a green coating. The presence of this bed of green-coated flints, known to borers as the Bull's Head Bed, was a proof that we had the true surface of the Chalk, the bed forming the basement of the Tertiary Series. Another interesting point connected with the Chalk here, was that it contained very little silex, for it had segregated in the form of flints; while, in the Ohalk without flints, the silex was probably distributed through the mass. Mr. Lines, who here joined the party, stated that in the bed above-mentioned sharks' teeth and oyster shells (Oatrea Bellovacina) were frequently found. Various sections exposed in the brickfields were then examined,
520
EXCURSION TO HERTFORD AND WARE.
the Professor explaining the relative position of the different beds, and their relations to each other, and to beds elsewhere which are here wanting. In this district he said that we had the lowest portion of the Tertiary Series seen north of London, hut not the lowest known in the London area, for while the Thanet Sands were being deposited south of the Thames, the Ohalk here was nearer the surface, not allowing of their deposition. The Woolwich and Reading Beds also were only partially represented. They consisted of alternations of sands and clays, and showed a very different set of conditions to that on the south of London, where there were 30 or 40 feet of ash-coloured sands. Here there were no freshwater shells, thongh these beds were contemporaneous with the freshwater beds found at Lewisham, &c., which contained a great number of shells. While south of London there were freshwater and estuarine conditions, in the north and west the deposits were entirely marine. Other beds which form a passage between the Woolwich and Reading Series and the London Olay, were next examined, and Professor Morris stated that they represented an important change of conditions. Their black flint-pebbles were interesting as being derived from unworn flints perfectly rolled on some sea-shore, and after being rounded, spread over the surface, where they were now found. These higher beds, the Basement-bed of the London Olay, evidenced a great depression of a very large area, extending between Marlborough, Hungerford and Harwich. From the brickfields the route lay across the fields to Little Amwell, near Hertford Heath, the highest point visited during the day, where excavations are in progress for a reservoir to supply the village with water. Here the Professor continued his lecture on the geology of the neighbourhood. Few districts were, he said, so interesting geologically as this and the adjacent ones which had been partly worked out by Professor Hughes. Other heights of the same level were seen around, and these elevations were the remnants of a surface of uniform height which had been cut into deeply by denudation, the present river-valleys being formed and gravel deposited. The gravel beds, of the higher levels, might be seen to contain pebbles from a great distance-Wales, Oumberland, and Scotland. They were the high-pebble gravels of Professor Hughes. It was improbable that they were here first formed in place 3S pebbles, some at least being pebbles of far older age. After the pebbles were deposited an emergence took place, and the land
EXCURSION TO HERTFORD AND WARE.
521
became scooped out, and great valleys were formed. During a period of submergence the Glacial or Boulder-clay materials were brought from the North; and here the Boulder-clay was seen to have mixed up the gravel of high-pebbles, and brought with it other materials. After this period a partial emergence took place, and after this emergence rain and rivers gave the present contour to the country, forming the third or River-gravel period, so that the district now presents the beds of High-pebble gravel, Boulder Clay and gravel, and Low-pebble gravel. From Little Amwell the route lay through the Walnut-tree Walk, and in refreshing shade, for the day was hot and the sun shone brightly, a halt was made for luncheon, after partaking of which the party passed through Amwell Bury, the romantic grounds of the Rev. D. Barclay Bevan, by permission of the Misses Bevan, and came upon the high road near the Amwell Hill lime-kilns, where a few fossils were found, and some fine examples of vertical "pipes," exposed at the sides of an extensive chalk-pit, were specially noticed. Climbing one of the sides of the pit, Amwell Magna was almost immediately reached, and the well-known spring which rises here from the Chalk, affording the New River Company a copious supply of water, was visited; but the beauty of the spot-the church above, the river flowing by, the finely-wooded hill-side, and the ornamental water reflecting the varied scene-diverted attention from the spring, and the interest attaching to its situation and origin. It is evidently a subterranean stream, flowing for some distance in the Chalk towards the river Lea, then passing under it and rising on the other side, and finding its way to the surface close to the river under which it flows. The next point of interest was near the New River Head, on the road from Ware to Hertford. Here the Diamond Rock Boring Company are boring for an additional supply of water for the New River Company. On arriving at the scene of operations, the party, by permission of the New River Company, and of Colonel Beaumont, C. Eo, Director of the Diamond Rock Boring Company, had the opportunity of becoming acquainted with the various methods of working adopted. The first operation consists in boring by means of compressed air-men working inside an iron cylinder into which air is pumped, which drives out round the edges any water which may accumulate, and materials which are loosened inside, while the cylinder is forced down from above. This preliminary
522
EXCURSION TO HERTFORD AlND WARE.
process had been given up, and the boring by diamonds had been carried on for some time. The shaft, commenced in February, had been carried to a depth of about 250 feet, a quarter of the entire distance intended, at an expense in diamonds alone of over £400 ; for although the diamonds rapidly cut away the hardest rock without showing any signs of wear, they become loose and break away by the wearing out of the steel socket in which they are fixed. They are set in rows tangentially at the bottom of a ring of varying dimension, the larger rings which are first used, being made to revolve more slowly than the smaller ones used at greater depths, where the bore-hole has to be smaller. At the present stage, a ring of 19i inches in diameter, making from 100 to 125 revolutions per minute, is being used, the motion being given by It 25·horse power steam engine. After this explanation, the foreman of the works most obligingly set his men to give a practical illustration of some of the processes, and the method of drawing the "core" and the "sludge" was duly exemplified. The Chadwell Springs, a few fields distant-better known as the New River Head-were next to have been visited, and the " Ermine Street," an old Roman road, and other indications of olden times, to have been explored, but evening was drawing near, and the party had to hasten from the boring to Ware Priory, the residence of Dr. J. Gwyn-Jeffreys, F.R.S., &c., who had invited the Members of the two Societies to tea. Here a sumptuous meal was provided, and after full justice had been done to it, Professor Morris, as President of the Geologists' Association, proposed a vote of thanks to Dr. and Mrs. Gwyn-Jeffreys, for their kind entertainment, which was seconded by Dr. Brett, as President of the County Society, and carried by acclamation. Dr. Gwyn-Jeffreys, in responding, referred to the long and tiring walk his visitors had accomplished, which he was sure was good for them, and for the ladies especially, of whom he was glad to see so many present. He was very pleased to see them all at the Priory, and hoped this would not be the last visit they would pay him. The party then took leave of their host and hostess, and left the Priory for Ware Station, the Members of the Geologists' Association returning to London by the Great Eastern Railway, and the Members of the Watford Society to Hertford, in the opposite direction, and thence to Watford and elsewhere.
1878.
Di1'ectors-The President, Professor MORRIS, F.G.S., and JOHN HOl'KINBON, Esq., F.L.S., F.G.S., Hon. Sec. Watford Nat. Hist. Soc. (RepC»'t by Mr. HOPKINSON.)
The northern edge of the London Tertiary Basin passes for a considerable portion of its course through the county of Hertford, and within the last few years several places along this line of outcrop have been visited by the Association, in conjunction with the Watford Natural History Society and Hertfordshire Field Club. On this occasion the neighbourhood of the county town was selected for investigation, and Members of the two Societies met at Hertford Station at half-past ten, the local Field Club forming by far the larger party. The first place visited was Hertford Castle, near which there are still standing, completely overgrown with ivy, the ruins of a much older structure, once an important fortress, supposed to have been built by King Alfred. From the Castle the route lay through the churchyard, famed for its fine avenue of chestnuts, 200 years old, and thence by permission through Ball's Park, the seat of the Marquis Townsend, to Mr. Lines' brickfield, between Rush Green and Little Amwell, the first point of geological interest. Before, however, the brickfields were visited, a chalk-pit near afforded Professor Morris the text for an interesting address, in the course of which he showed that the flints immediately above the Chalk were of a different colour to those in the Chalk, some chemical change having given them a green coating. The presence of this bed of green-coated flints, known to borers as the Bull's Head Bed, was a proof that we had the true surface of the Chalk, the bed forming the basement of the Tertiary Series. Another interesting point connected with the Chalk here, was that it contained very little silex, for it had segregated in the form of flints; while, in the Ohalk without flints, the silex was probably distributed through the mass. Mr. Lines, who here joined the party, stated that in the bed above-mentioned sharks' teeth and oyster shells (Oatrea Bellovacina) were frequently found. Various sections exposed in the brickfields were then examined,
520
EXCURSION TO HERTFORD AND WARE.
the Professor explaining the relative position of the different beds, and their relations to each other, and to beds elsewhere which are here wanting. In this district he said that we had the lowest portion of the Tertiary Series seen north of London, hut not the lowest known in the London area, for while the Thanet Sands were being deposited south of the Thames, the Ohalk here was nearer the surface, not allowing of their deposition. The Woolwich and Reading Beds also were only partially represented. They consisted of alternations of sands and clays, and showed a very different set of conditions to that on the south of London, where there were 30 or 40 feet of ash-coloured sands. Here there were no freshwater shells, thongh these beds were contemporaneous with the freshwater beds found at Lewisham, &c., which contained a great number of shells. While south of London there were freshwater and estuarine conditions, in the north and west the deposits were entirely marine. Other beds which form a passage between the Woolwich and Reading Series and the London Olay, were next examined, and Professor Morris stated that they represented an important change of conditions. Their black flint-pebbles were interesting as being derived from unworn flints perfectly rolled on some sea-shore, and after being rounded, spread over the surface, where they were now found. These higher beds, the Basement-bed of the London Olay, evidenced a great depression of a very large area, extending between Marlborough, Hungerford and Harwich. From the brickfields the route lay across the fields to Little Amwell, near Hertford Heath, the highest point visited during the day, where excavations are in progress for a reservoir to supply the village with water. Here the Professor continued his lecture on the geology of the neighbourhood. Few districts were, he said, so interesting geologically as this and the adjacent ones which had been partly worked out by Professor Hughes. Other heights of the same level were seen around, and these elevations were the remnants of a surface of uniform height which had been cut into deeply by denudation, the present river-valleys being formed and gravel deposited. The gravel beds, of the higher levels, might be seen to contain pebbles from a great distance-Wales, Oumberland, and Scotland. They were the high-pebble gravels of Professor Hughes. It was improbable that they were here first formed in place 3S pebbles, some at least being pebbles of far older age. After the pebbles were deposited an emergence took place, and the land
EXCURSION TO HERTFORD AND WARE.
521
became scooped out, and great valleys were formed. During a period of submergence the Glacial or Boulder-clay materials were brought from the North; and here the Boulder-clay was seen to have mixed up the gravel of high-pebbles, and brought with it other materials. After this period a partial emergence took place, and after this emergence rain and rivers gave the present contour to the country, forming the third or River-gravel period, so that the district now presents the beds of High-pebble gravel, Boulder Clay and gravel, and Low-pebble gravel. From Little Amwell the route lay through the Walnut-tree Walk, and in refreshing shade, for the day was hot and the sun shone brightly, a halt was made for luncheon, after partaking of which the party passed through Amwell Bury, the romantic grounds of the Rev. D. Barclay Bevan, by permission of the Misses Bevan, and came upon the high road near the Amwell Hill lime-kilns, where a few fossils were found, and some fine examples of vertical "pipes," exposed at the sides of an extensive chalk-pit, were specially noticed. Climbing one of the sides of the pit, Amwell Magna was almost immediately reached, and the well-known spring which rises here from the Chalk, affording the New River Company a copious supply of water, was visited; but the beauty of the spot-the church above, the river flowing by, the finely-wooded hill-side, and the ornamental water reflecting the varied scene-diverted attention from the spring, and the interest attaching to its situation and origin. It is evidently a subterranean stream, flowing for some distance in the Chalk towards the river Lea, then passing under it and rising on the other side, and finding its way to the surface close to the river under which it flows. The next point of interest was near the New River Head, on the road from Ware to Hertford. Here the Diamond Rock Boring Company are boring for an additional supply of water for the New River Company. On arriving at the scene of operations, the party, by permission of the New River Company, and of Colonel Beaumont, C. Eo, Director of the Diamond Rock Boring Company, had the opportunity of becoming acquainted with the various methods of working adopted. The first operation consists in boring by means of compressed air-men working inside an iron cylinder into which air is pumped, which drives out round the edges any water which may accumulate, and materials which are loosened inside, while the cylinder is forced down from above. This preliminary
522
EXCURSION TO HERTFORD AlND WARE.
process had been given up, and the boring by diamonds had been carried on for some time. The shaft, commenced in February, had been carried to a depth of about 250 feet, a quarter of the entire distance intended, at an expense in diamonds alone of over £400 ; for although the diamonds rapidly cut away the hardest rock without showing any signs of wear, they become loose and break away by the wearing out of the steel socket in which they are fixed. They are set in rows tangentially at the bottom of a ring of varying dimension, the larger rings which are first used, being made to revolve more slowly than the smaller ones used at greater depths, where the bore-hole has to be smaller. At the present stage, a ring of 19i inches in diameter, making from 100 to 125 revolutions per minute, is being used, the motion being given by It 25·horse power steam engine. After this explanation, the foreman of the works most obligingly set his men to give a practical illustration of some of the processes, and the method of drawing the "core" and the "sludge" was duly exemplified. The Chadwell Springs, a few fields distant-better known as the New River Head-were next to have been visited, and the " Ermine Street," an old Roman road, and other indications of olden times, to have been explored, but evening was drawing near, and the party had to hasten from the boring to Ware Priory, the residence of Dr. J. Gwyn-Jeffreys, F.R.S., &c., who had invited the Members of the two Societies to tea. Here a sumptuous meal was provided, and after full justice had been done to it, Professor Morris, as President of the Geologists' Association, proposed a vote of thanks to Dr. and Mrs. Gwyn-Jeffreys, for their kind entertainment, which was seconded by Dr. Brett, as President of the County Society, and carried by acclamation. Dr. Gwyn-Jeffreys, in responding, referred to the long and tiring walk his visitors had accomplished, which he was sure was good for them, and for the ladies especially, of whom he was glad to see so many present. He was very pleased to see them all at the Priory, and hoped this would not be the last visit they would pay him. The party then took leave of their host and hostess, and left the Priory for Ware Station, the Members of the Geologists' Association returning to London by the Great Eastern Railway, and the Members of the Watford Society to Hertford, in the opposite direction, and thence to Watford and elsewhere.