| Title: | Guest Contribution: The Tree-Ring Dating of Pikes Farm, Michaelchurch Escley, Herefordshire |
| Date: | 2007 |
Introduction:
This report was commissioned by Tony Gray, the then owner, as part of his detailed studies of the origins, history, ownership and structure of Pikes Farm in the Upper Escley Valley, Michaelchurch. It is reproduced here with the kind permission of his widow.
Tony’s paper on Pikes Farm incorporating these findings and a commentary on them are also available on the website.
Ewyas Lacy Study Group
Oxford Dendrochronology Laboratory
Interim Report 2007/24
The Tree-Ring Dating of Pikes Farm,
Michaelchurch Escley, Herefordshire
M J Worthington and Dr D W H Miles FSA
Summary:
MICHAELCHURCH ESCLEY, Pikes Farm (SO 2907 3815)
(a) East end door frames Felling date ranges: 1457-87 and 1462-92
(b) Second phase of hall house Felling date: c. 1546
(c) Parlour range Felling date range: Summer 1561
(d) Later window frames Felling date range: Winter 1590/91
(a) Door lintel 1446(h/s); Door post 1451(2); (b) Chimney lintel 1532(44+13C NM); Longitudinal beam in dairy 1540(14); Cruck (0/1); Ex situ crucks 1529(h/s), 1516; Ex situ plank-and-muntin planks 1483, 1420; (c) Cross-beams 1561(17½C), 1541(1); Tiebeam 1539(h/s); Studs(0/2); (d) Window cills 1590 (24C), 1485; Window head 1557(3), Window mullion 1461. Site Master 1342-1590 MLCHRCH2 (t = 10.6 HEREFC; 10.4 WVT9; 10 WALES97)
A substantial stone farm house comprising an original north-south orientated single storey hall house/longhouse with subsequently raised roof line and an east-west orientated two storey extension on its north-east corner, forming an overall “L” shape. The longhouse section now comprises three bays – the original byre and cross passage forming a lounge; the hall; and, at the north end, the dairy/service room. A substantial chimney with spiral stair, facing into the hall, occupies space in the original cross passage. The hall and dairy have first floor accommodation and a small modern two storey extension has been built in the north-west corner of the “L” shape. The east-west extension comprises one large room on each of ground and first floors now comprising a kitchen and bedroom respectively. A large chimney with spiral stair occupies the eastern gable end.
Date sampled: 2nd July 2006
Owner & Commissioner: Mr Tony Gray
Historical Research: Mr Tony Gray and Richard Suggett FSA
Summary published: Miles, D H, Worthington, M J, and Bridge, M C, 2007 Tree-ring dates, Vernacular Architecture 38, (forthcoming)
Oxford Dendrochronology Laboratory
Mill Farm, Mapledurham, South Oxfordshire, RG4 7TX
daniel.miles@rlaha.ox.ac.uk & michael.worthington@rlaha.ox.ac.uk
www.dendrochronology.com
July 2007
How Dendrochronology Works
Dendrochronology has over the past 20 years become one of the leading and most accurate scientific dating methods. Whilst not always successful, when it does work, it is precise, often to the season of the year. Tree-ring dating is well known for its use in dating historic buildings and archaeological timbers to this degree of precision. However more ancillary objects such as doors, furniture, panel paintings, and wooden boards in medieval book-bindings can sometimes be successfully dated.
The science of dendrochronology is based on a combination of biology and statistics. Fundamental to understanding how dendrochronology works is the phenomenon of tree growth. Essentially, trees grow through the addition of both elongation and radial increments. The elongation takes place at the terminal portions of the shoots, branches, and roots, while the radial increment is added by the cambium, the zone of living cells between the wood and the bark. In general terms, a tree can be best simplified by describing it as a cone, with a new layer being added to the outside each year in temperate zones, making it wider and taller.
An annual ring is composed of the growth which takes place during the spring and summer until about November when the leaves are shed and the tree becomes dormant for the winter period. For the European oak (Quercus robur and Q. petraea), as well as many other species, the annual ring is composed of two distinct parts - the spring growth or early wood, and the summer growth, or late wood. Early wood is composed of large vessels formed during the period of shoot growth which takes place between March and May, which is before the establishment of any significant leaf growth, and is produced by using most of the energy and raw materials laid down the previous year. Then, there is an abrupt change at the time of leaf expansion around May or June when hormonal activity dictates a change in the quality of the xylem and the summer, or late wood is formed. Here the wood becomes increasingly fibrous and contains much smaller vessels. Trees with this type of growth pattern are known as ring-porous, and are distinctive in the contrasting open, light-coloured early wood vessels compared to the dense, darker-coloured late wood.
Dendrochronology utilises the variation in the width of the annual rings as influenced by climatic conditions common to a large area, as opposed to other more local factors such as woodland competition and insect attack. It is through the comparison of these climate-induced variations in ring widths that allows calendar dates to be ascribed from a firmly-dated sequence to one which is not. If a tree section is complete to the bark edge, then when dated a precise date of felling can be determined, precise to the season of the year, depending on the degree of formation of the outermost ring. Therefore, a tree with bark which has the spring vessels formed but no summer growth can be said to be felled in the spring, although it is not possible to say in which particular month the tree was felled.
Section of tree with conversion methods showing three types of sapwood retention resulting in A terminus post quem, B a felling date range, and C a precise felling date. Enlarged area D shows the outermost rings of the sapwood with growing seasons (Miles 1997, 42)
Another important dimension to dendrochronological studies is the presence of sapwood. This is the band of growth rings immediately beneath the bark and comprises the living growth rings which transport the sap from the roots to the leaves. This sapwood band is distinguished from the heartwood by the prominent features of colour change and the blocking of the spring vessels with tyloses, the waste products of the tree’s growth. The heartwood is generally darker in colour, and the spring vessels are blocked with tyloses. The heartwood is dead tissue, whereas the sapwood is living, although the only really living, growing, cells are in the cambium, immediately beneath the bark. In European oak (Quercus robur sp), the difference in colour is generally matched by the change in the spring vessels. Generally the sapwood retains stored food and is therefore attractive to insect and fungal attack once the tree is felled and therefore is often removed during conversion.
Sapwood in European oaks tends to be of a relatively constant width and/or number of rings. By determining what this range is with an empirically or statistically-derived estimate is a valuable aspect in the interpretation of tree-ring dates where the bark edge is not present (Miles 1997). The narrower this range of sapwood rings, the more precise the estimated felling date range will be.
Methodology: The Dating Process
All timbers sampled were of oak (Quercus spp.) from what appeared to be primary first-use timbers, or any timbers which might have been re-used from an early phase. Those timbers which looked most suitable for dendrochronological purposes with complete sapwood or reasonably long ring sequences were selected. In situ timbers were sampled through coring, using a 16mm hollow auger. Details and locations of the samples are detailed in the summary table.
The dry samples were sanded on a linisher, or bench-mounted belt sander, using 60 to 1200 grit abrasive paper, and were cleaned with compressed air to allow the ring boundaries to be clearly distinguished. They were then measured under a x10/x30 microscope using a travelling stage electronically displaying displacement to a precision of 0.01mm. Thus each ring or year is represented by its measurement which is arranged as a series of ring-width indices within a data set, with the earliest ring being placed at the beginning of the series, and the latest or outermost ring concluding the data set.
The principle behind tree-ring dating is a simple one: the seasonal variations in climate-induced growth as reflected in the varying width of a series of measured annual rings is compared with other, previously dated ring sequences to allow precise dates to be ascribed to each ring. When an undated sample or site sequence is compared against a dated sequence, known as a reference chronology, an indication of how good the match is must be determined. Although it is almost impossible to define a visual match, computer comparisons can be accurately quantified. Whilst it may not be the best statistical indicator, Student’s (a pseudonym for W S Gosset) t-value has been widely used amongst British dendrochronologists. The cross-correlation algorithms most commonly used and published are derived from Baillie and Pilcher’s CROS programme (Baillie and Pilcher 1973), although a faster version (Munro 1984) giving slightly different t-values is sometimes used for indicative purposes.
Generally, t-values over 3.5 should be considered to be significant, although in reality it is common to find demonstrably spurious t-values of 4 and 5 because more than one matching position is indicated. For this reason, dendrochronologists prefer to see some t-value ranges of 5, 6, or higher, and for these to be well replicated from different, independent chronologies with local and regional chronologies well represented. Users of dates also need to assess their validity critically. They should not have great faith in a date supported by a handful of t-values of 3’s with one or two 4’s, nor should they be entirely satisfied with a single high match of 5 or 6. Examples of spurious t-values in excess of 7 have been noted, so it is essential that matches with reference chronologies be well replicated, and that this is confirmed with visual matches between the two graphs. Matches with t-values of 10 or more between individual sequences usually signify having originated from the same parent tree.
In reality, the probability of a particular date being valid is itself a statistical measure depending on the t-values. Consideration must also be given to the length of the sequence being dated as well as those of the reference chronologies. A sample with 30 or 40 years growth is likely to match with high t-values at varying positions, whereas a sample with 100 consecutive rings is much more likely to match significantly at only one unique position. Samples with ring counts as low as 50 may occasionally be dated, but only if the matches are very strong, clear and well replicated, with no other significant matching positions. This is essential for intra-site matching when dealing with such short sequences. Consideration should also be given to evaluating the reference chronology against which the samples have been matched: those with well-replicated components which are geographically near to the sampling site are given more weight than an individual site or sample from the opposite end of the country.
It is general practice to cross-match samples from within the same phase to each other first, combining them into a site master, before comparing with the reference chronologies. This has the advantage of averaging out the ‘noise’ of individual trees and is much more likely to obtain higher t-values and stronger visual matches. After measurement, the ring-width series for each sample is plotted as a graph of width against year on log-linear graph paper. The graphs of each of the samples in the phase under study are then compared visually at the positions indicated by the computer matching and, if found satisfactory and consistent, are averaged to form a mean curve for the site or phase. This mean curve and any unmatched individual sequences are compared against dated reference chronologies to obtain an absolute calendar date for each sequence. Sometimes, especially in urban situations, timbers may have come from different sources and fail to match each other, thus making the compilation of a site master difficult. In this situation samples must then be compared individually with the reference chronologies.
Therefore, when cross-matching samples with each other, or against reference chronologies, a combination of both visual matching and a process of qualified statistical comparison by computer is used. The ring-width series were compared on an IBM compatible computer for statistical cross-matching using a variant of the Belfast CROS program (Baillie and Pilcher 1973). A version of this and other programmes were written in BASIC by D Haddon-Reece, and re-written in Microsoft Visual Basic by M R Allwright and P A Parker.
Ascribing and Interpreting Felling Dates
Once a tree-ring sequence has been firmly dated in time, a felling date, or date range, is ascribed where possible. For samples which have sapwood complete to the underside of, or including bark, this process is relatively straight forward. Depending on the completeness of the final ring, i.e. if it has only the early-wood formed, or the latewood, a precise felling date and season can be given. If the sapwood is partially missing, or if only a heartwood/sapwood transition boundary survives, then an estimated felling date range can be given for each sample. The number of sapwood rings can be estimated by using a statistically derived sapwood estimate with a given confidence limit. A review of the geographical distribution of dated sapwood data from historic building timbers has shown that a 95% range of 12-41 rings is most appropriate for the Wales and the border counties (Miles 1997), which will be used here. If no sapwood or heartwood/sapwood boundary survives, then the minimum number of sapwood rings from the appropriate sapwood estimate is added to the last measured ring to give a terminus post quem (tpq) or felled after date.
Some caution must be used in interpreting solitary precise felling dates. Many instances have been noted where timbers used in the same structural phase have been felled one, two, or more years apart. Whenever possible, a group of precise felling dates should be used as a more reliable indication of the construction period. It must be emphasised that dendrochronology can only date when a tree has been felled, not when the timber was used to construct the structure under study. However, it is common practice to build timber-framed structures with green or unseasoned timber and that construction usually took place within twelve months of felling (Miles 1997).
Details of Dendrochronological Analysis
The results of the dendrochronological analysis for the building under study are presented in a number of detailed tables. The most useful of these is the summary Table 1. This gives most of the salient results of the dendrochronological process, and includes details for each sample, its location, and its felling date or date range, if successfully tree-ring dated. This last column is of particular interest to the end user, as it gives the actual year and season when the tree was felled, if bark is present, or an estimated felling date range if the sapwood is incomplete. Occasionally it will be noted that the felling date ranges may coincide with the precise felling date ranges. This is nothing to be overly concerned about so long as these are not too far apart. It must be remembered that the estimated felling date ranges are calculated at a 95% confidence level, which means that statistically one sample in 20 will have felling dates which actually fall outside the predicted range.
It will also be noticed that often the precise felling dates will vary within several years of each other. Unless there is supporting archaeological evidence suggesting different phases, all this would indicate is either stockpiling of timber, or of trees which have been felled or died at varying times but not cut up until the commencement of the particular building operations in question. When presented with varying precise felling dates, one should always take the latest date for the structure under study, and it is likely that construction will have been completed for ordinary vernacular buildings within twelve or eighteen months from this latest felling date (Miles 1997).
Table 2 shows the degree with which the multiple radii have cross-matched with each other to form same-timber means. This shows the t-value over the number of years overlap for each combination of samples in a matrix table. It should be born in mind that t-values with less than 80 rings overlap may not truly reflect the same degree of match and that spurious matches may produce similar values. Once the individual multiple samples from the same timber have been combined, then these are compared with other samples from the site and any which are found to have originated from the same parent tree are again similarly combined, and the matches shown with a matrix table of t-values and overlaps.
Finally, all samples, including all same timber and same tree means are combined to form one or more site masters. Again, the cross-matching is shown as a matrix table. Reference should always be made to Table 1 to clearly identify which components have been combined.
Table 3 shows the degree of cross-matching between the site master(s) with a selection of reference chronologies. This shows the county or region from which the reference chronology originated, the common chronology name together with who compiled the chronology with publication reference and the years covered by the reference chronology. The years overlap of the reference chronology and the site master being compared are also shown together with the resulting t-value. It should be appreciated that well replicated regional reference chronologies, which are shown in bold, will often produce better matches then with individual site masters or indeed individual sample sequences.
Figures include a bar diagram which shows the chronological relationship between two or more dated samples from a phase of building. The site sample record sheets are also appended, together with any plans showing sample locations, if available.
Publication of all dated sites are published in Vernacular Architecture annually, and the entry, if available, is shown on the summary page of the report. This does not give as much technical data for the samples dated, but does give the t-value matches against the relevant chronologies, provide a short descriptive paragraph for each building or phase dated, and gives a useful short summary of samples dated. These summaries are also listed on the web-site maintained by the Laboratory, which can be accessed at www.dendrochronology.com. The Oxford Dendrochronology Laboratory retains copyright of this report, but the commissioner of the report has the right to use the report for his/her own use so long as the authorship is quoted. Primary data and the resulting site master(s) used in the analysis is available from the Laboratory on request by the commissioner and bona fide researchers. The samples form part of the Laboratory archives.
Summary of Dating
A total of 21 samples were taken from 19 timbers comprising four phases. Nine timbers were from the second phase of the hall house, five were from the parlour range, four were from various ex situ or reused timbers, and one was taken from the south truss of the top barn. Some of the timbers sampled in the second phase of the hall house included later alterations such as windows and a chimney lintel.
All of the timbers were cross-matched together, and two cross beams from the parlour range (mepf11 and mepf12) were found to have originated from the same tree, and were combined to form the same-tree mean mepf1112. This was found to match with 12 other timbers and were combined to form the 249-year site master MLCHRCH2 (Table 2). This was dated, spanning the years 1342-1590. Excellent matches were found with two other chronologies from the King’s Arms, Michaelchurch Escley, as well as other local chronologies from Herefordshire and the Welsh borders (Table 3a). The remaining undated samples were compared with this site master as well as the reference chronologies, and only one other dated. Sample mepf24 matched with the site master with a t-value of 4.21 and this was confirmed with other matches with the reference chronologies (Table 3b).
The results are somewhat complicated, given the number of subsequent alterations. The second phase of the hall range is probably represented by the door lintel and post at the east end (mepf1 and mepf2) which produced felling date ranges of 1457-87 and 1462-92 respectively. However, careful study of the fabric of the building is required to ensure that these elements are not reused. The next phase of construction in the hall part of the house is a chimney lintel (mepf3) and a longitudinal beam in the Dairy (mepf4a), which produced felling dates ranges of circa 1546 and 1541-66 respectively. One window cill (mepf7) produced a precise felling date of winter 1590/91, whilst a window head (mepf8) produced a compatible felling date range of 1568-98. Two other timbers from window frames (mepf6 and mepf9) produced termini post quem dates of after 1472 and 1496, and are probably part of the same phase as the 1590/91 felling date for the sample mepf7, but with a substantial number of heartwood rings removed in the conversion of the timber. Two samples from the east cruck of the south truss failed to date or to match each other, due primarily to the timber being too fast grown.
Of the five timbers sampled from the parlour range, three dated. The second cross beam on the west side (mepf11) produced a precise felling date of summer 1561, and although the third cross beam adjacent (mepf12) did not retain complete sapwood, it was found to have originated from the same tree as (mepf11), and therefore had to have also been felled in the summer of 1561. The tiebeam of the west truss (mepf15) did not retain complete sapwood, but produced a felling date range of 1550-80, entirely consistent with the 1561 felling dates for the other two dated timbers. Two studs from the east truss failed to date.
Four ex situ timbers dated. Two crucks (mepf21 and mepf22), thought to have been from the primary phase dated to 1540-70 and after 1527. However, either the door frame from the hall is actually reused, or the crucks are broadly contemporary with the 1561 parlour range. Two posts from a plank and muntin wall were also dated (mepf23 and mepf24), but as neither retained any heartwood sapwood boundaries, the termini post quem dates of after 1431 and after 1494 are less helpful in interpreting the early part of the building, and appear to be somewhat later than the hall doorframe.
Finally, a single sample taken from the top barn failed to date as it was fast grown, with only 52 rings.
References
Baillie, M G L, and Pilcher, J R, 1973 A simple cross-dating program for tree-ring research, Tree-Ring Bulletin, 33, 7-14
Bridge, M C, 1998 Compilation of master chronologies from the South, unpubl computer file SENG98, University of London Dendrochronology Laboratory
Groves, C, 1997, Dendrochronological analysis of Ightfield Hall Farm Barn, Ightfield, Whitchurch, Shropshire, Anc Mon Lab Rep, 91/97
Hillam, J, and Groves, C, 1994 Compilation of master chronologies from the North, unpubl computer file NORTH, Sheffield Dendrochronology Laboratory
Miles, D H, 1995 Working compilation of 71 reference chronologies centred around Shropshire by various researchers, unpubl computer file SALOP95, Oxford Dendrochronology Laboratory
Miles, D H, 1997 The interpretation, presentation, and use of tree-ring dates, Vernacular Architecture, 28, 40-56
Miles, D H, 1997b Working compilation of 58 reference chronologies centred around Wales by various researchers, unpubl computer file WALES97, Oxford Dendrochronology Laboratory
Miles, D W H, 2002 The Tree-Ring Dating at Abbey House, Buildwas Abbey, Shropshire, Centre for Archaeol Rep, 27/2002
Miles, D H, and Haddon-Reece, D, 1994 List 56 - Tree-ring dates, Vernacular Architect, 25, 28–36
Miles, D H, and Haddon-Reece, D 1996 List 72 - Tree-ring dates, Vernacular Architect, 27, 97–102
Miles, D H, and Worthington, M J, 1998 Tree-ring dates, Vernacular Architect 29, 111–29
Miles, D H, and Worthington, M J, 1999 Tree-ring dates, Vernacular Architect 30, 98–113
Miles, D H, and Worthington, M J, 2002 Tree-ring dates, Vernacular Architect 33, 81–102
Munro, M A R, 1984 An improved algorithm for cross tree-dating, Tree Ring Bulletin, 44, 17-27.
Nayling, N, 1999 Tree-ring analysis of oak timbers from Shrewsbury Abbey Church, Anc Mon Lab Rep, 39/99
Nayling, N, 2000 Tree-ring analysis of timbers from The White House, Vowchurch, Herefordshire, Anc Mon Lab Rep, 73/99
Tyers, I, 1996 The tree-ring analysis of six secular buildings from the city of Hereford, Anc Mon Lab Rep, 17/96
Worthington, M J, and Miles, D H, 2007 Tree-ring dates, Vernacular Architect 29, 111–29
Worthington, M J, and Miles, D W H 2001 The Tree-Ring Dating of Upper Lake, Westbury, Shropshire, Centre for Archaeol Rep, 42/2001
Table 1: Summary of Tree-Ring Dating
PIKES FARM, MICHAELCHURCH ESCLEY, HEREFORDSHIRE
| Sample number & type | Timber and position | Dates AD spanning | H/S bdry | Sapwood complement | No of rings | Mean width mm | Std devn mm | Mean sens mm | Felling seasons and dates/date ranges (AD) | |
| 2nd phase of hall house |
|
|
|
|
|
|
|
| ||
| *mepf1 | c | Door lintel east end | 1368-1446 | 1446 | H/S | 79 | 1.80 | 0.66 | 0.228 | 1457-1487 |
| *mepf2 | c | Door post east end | 1362-1451 | 1449 | 2 | 90 | 1.73 | 0.83 | 0.220 | 1462-1492 |
| *mepf3 | c | Chimney lintel | 1405-1532 | 1488 | 44+13C NM | 128 | 1.80 | 1.27 | 0.242 | c.1546 |
| *mepf4a | c | Longitudinal beam dairy | 1427-1540 | 1525 | 15 | 114 | 2.02 | 0.92 | 0.156 | 1541-1566 |
| mepf4b | c | ditto | - |
| +14C | 14 | 1.07 | 0.13 | 0.136 |
|
| mepf5a | c | East cruck south truss | - |
|
| 35 | 2.39 | 0.61 | 0.162 |
|
| mepf5b | c | ditto | - |
|
| 43 | 2.09 | 0.65 | 0.200 |
|
| *mepf6 | c | Window cill | 1342-1485 |
|
| 144 | 2.13 | 0.85 | 0.143 | After 1496 |
| *mepf7 | c | Window cill | 1462-1590 | 1566 | 24C | 129 | 0.97 | 0.37 | 0.188 | Winter 1590/91 |
| *mepf8 | c | Window head | 1421-1557 | 1554 | 3 | 137 | 1.42 | 0.49 | 0.137 | 1568-1598 |
| *mepf9 | c | Window mullion centre Dairy | 1383-1461 |
|
| 79 | 1.49 | 0.34 | 0.119 | After 1472 |
| Parlour Range |
|
|
|
|
|
|
|
| ||
| mepf11 | c | Cross beam 2nd west side | 1437-1560 | 1543 | 17½C | 124 | 2.31 | 0.47 | 0.161 | Summer 1561 |
| mepf12 | c | Cross beam 3rd west side | 1424-1541 |
| 1 | 118 | 1.88 | 0.44 | 0.145 | (Summer 1561) |
| *mepf1112 |
| Same-tree mean mepf11 + mepf12 | 1424-1560 | 1543 | 17½C | 137 | 2.12 | 0.41 | 0.151 | Summer 1561 |
| mepf13 | c | North stud east truss | - |
| 3 | 94 | 1.54 | 0.45 | 0.226 |
|
| mepf14 | c | South stud east truss | - |
| H/S | 81 | 1.84 | 0.61 | 0.201 |
|
| *mepf15 | c | Tiebeam west truss | 1482-1539 | 1539 | H/S | 58 | 2.71 | 0.58 | 0.193 | 1550-1580 |
| Ex-situ timbers |
|
|
|
|
|
|
|
| ||
| *mepf21 | s | cruck possible primary phase | 1382-1529 | 1529 | H/S | 148 | 1.20 | 0.68 | 0.185 | 1540-1570 |
| *mepf22 | s | cruck possible primary | 1430-1516 |
|
| 87 | 3.78 | 1.12 | 0.160 | After 1527 |
| *mepf23 | c | post from plank and muntin wall | 1343-1420 |
|
| 78 | 2.58 | 0.73 | 0.203 | After 1431 |
| mepf24 | c | post from plank and muntin wall | 1427-1483 |
|
| 57 | 2.06 | 0.67 | 0.183 | After 1494 |
| Top barn south truss |
|
|
|
|
|
|
|
| ||
| mepf31 | c | tiebeam | - |
| 18C | 52 | 3.09 | 1.21 | 0.231 |
|
|
|
|
|
|
|
|
|
|
|
|
|
| * = MLCHRCH2 Site Master | 1342-1590 |
|
| 249 | 1.83 | 0.72 | 0.140 |
| ||
Key: *, †, § = sample included in site-master; c = core; mc = micro-core; s = slice/section; g = graticule; p = photograph; ¼C, ½C, C = bark edge present, partial or complete ring: ¼C = spring (last partial ring not measured), ½C = summer/autumn (last partial ring not measured), or C = winter felling (ring measured); H/S bdry = heartwood/sapwood boundary - last heartwood ring date; std devn = standard deviation; mean sens = mean sensitivity.
Explanation of terms used in Table 1
The summary table gives most of the salient results of the dendrochronological process. For ease in quickly referring to various types of information, these have all been presented in Table 1. The information includes the following categories:
Sample number: Generally, each site is given a two or three letter identifying prefix code, after which each timber is given an individual number. If a timber is sampled twice, or if two timbers were noted at time of sampling as having clearly originated from the same tree, then they are given suffixes ‘a’, ‘b’, etc. Where a core sample has broken, with no clear overlap between segments, these are differentiated by a further suffix ‘1’, ‘2’, etc.
Type shows whether the sample was from a core ‘c’, or a section or slice from a timber‘s’. Sometimes photographs are used ‘p’, or timbers measured in situ with a graticule ‘g’.
Timber and position column details each timber sampled along with a location reference. This will usually refer to a bay or truss number, or relate to compass points or to a reference drawing.
Dates AD spanning gives the first and last measured ring dates of the sequence (if dated),
H/S bdry is the date of the heartwood/sapwood transition or boundary (if present). This date is critical in determining an estimated felling date range if the sapwood is not complete to the bark edge.
Sapwood complement gives the number of sapwood rings. The tree starts growing in the spring during which time the earlywood is produced, also known also as spring growth. This consists of between one and three decreasing spring vessels and is noted as Spring felling and is indicated by a ¼ C after the number of sapwood ring count. Sometimes this can be more accurately pin-pointed to very early spring when just a few spring vessels are visible. After the spring growing season, the latewood or summer growth commences, and is differentiated from the proceeding spring growth by the dense band of tissue. This summer growth continues until just before the leaves drop, in about October. Trees felled during this period are noted as summer felled (½ C), but it is difficult to be too precise, as the width of the latewood can be variable, and it can be difficult to distinguish whether a tree stopped growing in autumn or winter. When the summer growth band is clearly complete, then the tree would have been felled during the dormant winter period, as shown by a single C. Sometimes a sample will clearly have complete sapwood, but due either to slight abrasion at the point of coring, or extremely narrow growth rings, it is impossible to determine the season of felling.
Number of rings: The total number of measured rings on the samples analysed. If the pith is included or near to the beginning of the sequence, this is indicated by a Θ symbol if the pith is included in sample; Φ if within 5 rings of centre; and Ω if within 10 rings of centre.
Mean ring width: This, simply put, is the sum total of all the individual ring widths, divided by the number of rings, giving an average ring width for the series.
Mean sensitivity: A statistic measuring the mean percentage, or relative, change from each measured yearly ring value to the next; that is, the average relative difference from one ring width to the next, calculated by dividing the absolute value of the differences between each pair of measurements by the average of the paired measurements, then averaging the quotients for all pairs in the tree-ring series (Fritts 1976). Sensitivity is a dendrochronological term referring to the presence of ring-width variability in the radial direction within a tree which indicates the growth response of a particular tree is “sensitive” to variations in climate, as opposed to complacency.
Standard deviation: The mean scatter of a population of numbers from the population mean. The square root of the variance, which is itself the square of the mean scatter of a statistical population of numbers from the population mean. (Fritts 1976).
Felling seasons and dates/date ranges is probably the most important column of the summary table. Here the actual felling dates and seasons are given for each dated sample (if complete sapwood is present). Sometimes it will be noticed that often the precise felling dates will vary within several years of each other. Unless there is supporting archaeological evidence suggesting different phases, all this would indicate is either stockpiling of timber, or of trees which have been felled or died at varying times but not cut up until the commencement of the particular building operations in question. When presented with varying precise felling dates, one should always take the latest date for the structure under study, and it is likely that construction will have been completed for ordinary vernacular buildings within twelve or eighteen months from this latest felling date (Miles 1997).
Table 2: Matrix of t-values and overlaps for same-timber means and site masters
Components of Site Master MLCHRCH2
| Sample: | mepf2 | mepf3 | mepf4a | mepf6 | mepf7 | mepf8 | mepf9 | mepf1112 | mepf15 | mepf21 | mepf22 | mepf23 |
| Last ring date AD: | 1451 | 1532 | 1540 | 1485 | 1590 | 1557 | 1461 | 1560 | 1539 | 1529 | 1516 | 1420 |
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| mepf1 | 2.37 | 2.06 | 2.17 | 6.64 | 0.00 | 1.57 | 4.60 | 1.90 | 0.00 | 5.94 | 1.59 | 4.18 |
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| 79 | 42 | 20 | 79 | 00 | 26 | 64 | 23 | 00 | 65 | 17 | 53 |
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| mepf2 | 2.66 | 3.41 | 3.44 | 0.00 | 3.57 | 2.24 | 2.65 | 0.00 | 5.42 | 1.19 | 2.23 |
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| 47 | 25 | 90 | 00 | 31 | 69 | 28 | 00 | 70 | 22 | 59 |
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| mepf3 | 4.62 | 3.67 | 3.40 | 5.05 | 3.88 | 5.52 | 4.41 | 4.84 | 4.00 | 2.24 |
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| 106 | 81 | 71 | 112 | 57 | 109 | 51 | 125 | 87 | 16 |
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| mepf4a | 2.68 | 2.36 | 2.99 | 3.62 | 4.73 | 3.58 | 4.89 | 5.23 | 0.00 |
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| 59 | 79 | 114 | 35 | 114 | 58 | 103 | 87 | 00 |
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| mepf6 | 2.88 | 3.61 | 5.32 | 2.96 | 0.00 | 5.50 | 2.76 | 4.59 |
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| 24 | 65 | 79 | 62 | 62 | 104 | 56 | 78 |
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| mepf7 | 4.83 | 0.00 | 4.74 | 3.23 | 2.83 | 5.14 | 0.00 |
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| 96 | 00 | 99 | 58 | 68 | 55 | 00 |
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| mepf8 | 4.38 | 7.39 | 4.38 | 5.01 | 2.39 | 0.00 |
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| 41 | 134 | 58 | 109 | 87 | 00 |
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| mepf9 | 3.14 | 0.00 | 4.70 | 0.64 | 0.03 |
| Components of same-tree mean mepf1112 |
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| 38 | 00 | 79 | 32 | 38 | |||
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| Sample: | mepf12 |
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| mepf1112 | 6.23 | 7.93 | 4.33 | 0.00 |
| Last ring | 1541 |
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| 58 | 106 | 87 | 00 |
| date AD: |
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| mepf15 | 4.86 | 5.92 | 0.00 |
| mepf11 | 12.03 |
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| 48 | 35 | 00 |
| 1560 | 105 |
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| mepf21 | 4.45 | 2.48 |
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| 87 | 39 |
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| mepf22 | 0.00 |
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| 00 |
Table 3a: Dating of site master MLCHRCH2 (1342-1590) against reference chronologies at 1693
| County or region: | Chronology name: | Short publication reference: | File name: | Spanning: | Overlap: | t-value: |
| Herefordshire | Kings Arms Michaelchurch Escley | (Worthington and Miles 2007) | MLCHRCH3 | 1444-1535 | 92 | 6.17 |
| Wales | Gwernfyda Llanllugan | (Miles and Haddon-Reece 1996) | GWRNFYDA | 1410-1551 | 142 | 8.10 |
| Northern England | Northern England Master | (Hillam and Groves 1994) | NORTH | 440-1742 | 249 | 8.11 |
| Shropshire | Upton Cressett | (Miles and Haddon-Reece 1994) | CRESSETT | 1298-1498 | 157 | 8.25 |
| Wales | Old Burfa, Evenjobb, Rads | (Miles and Worthington 1998) | OLDBRAFA1 | 1347-1487 | 141 | 8.45 |
| Shropshire | Ightfield Hall barn, Whitchurch | (Groves 1997) | IGHTFELD | 1341-1566 | 225 | 9.18 |
| Herefordshire | Kings Arms Michaelchurch Escley | (Worthington and Miles 2007) | MLCHRCH4 | 1370-1497 | 128 | 9.38 |
| Wales | Welsh Master Chronology | (Miles 1997) | WALES97 | 404-1981 | 249 | 10.02 |
| Herefordshire | White House, Vowchurch | (Nayling 2000) | WVT9 | 1364-1602 | 227 | 10.41 |
| Herefordshire | Farmer's Club, Hereford | (Tyers 1996) | HEREFC | 1313-1617 | 249 | 10.63 |
Chronologies shown in bold are composite chronologies
Table 3b: Dating of site master mepf24 (1427-1483) against reference chronologies at 1483
| County or region: | Chronology name: | Short publication reference: | File name: | Spanning: | Overlap: | t-value: |
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| Wales | Welsh Master Chronology | (Miles 1997) | WALES97 | 404-1981 | 57 | 4.50 |
| England | Southern England Master | (Bridge 1998) | SENG98 | 944-1790 | 57 | 4.55 |
| Shropshire | Buildwas Abbey | (Miles 2002) | BUILDWS2 | 1374-1547 | 57 | 4.62 |
| Shropshire | Coats Farm | (Miles and Haddon-Reece 1996) | COATSFM | 1346-1485 | 57 | 4.68 |
| Staffordshire | Sinai Park | (Tyers 1997) | SINAI | 1227-1750 | 57 | 4.69 |
| Shropshire | Clungunford Master Chronology | (Miles 2002 unpubl) | CLNGNFRD | 1273-1653 | 57 | 4.79 |
| Shropshire | Rowton Grange, Clungunford | (Miles and Worthington 2002) | CGFE | 1407-1597 | 57 | 4.77 |
| Shropshire | Shropshire Master Chronology | (Miles 1995) | SALOP95 | 881-1745 | 57 | 4.70 |
| Wales | Rose and Crown, Gwydwn | (Miles and Worthington 2000) | GWYDWN | 1411-1571 | 57 | 4.87 |
| Hampshire | Rye Cottage, Mapledurwell | (Miles and Worthington 1999) | rye7 | 1377-1525 | 57 | 4.84 |
| Shropshire | Shrewsbury Abbey Church | (Nayling 1999) | SACM2 | 1375-1493 | 57 | 5.32 |
| Shropshire | Upper Lake, Westbury | (Worthington and Miles 2000) | UPRLAKE | 1418-1546 | 57 | 5.36 |
Bar diagram showing dated timbers in chronological position
Ref: tg_mic_0159