No. 83/84, 2007 70 Ontario Archaeology
For the Record: The What, How and When of Stratigraphy
Henry C. Cary and Joseph H. Last
Ontario archaeologists approach stratigraphy from a number ofdirections, a situation born from the adop tion and adaptation of Canadian, American, and British field techniques. Each method is suitable for cer tain conditions, but we suggest that stratigraphic excavation must be used to understand site formation. Our technique focuses on the single stratigraphic unit and asks ofit three questions: what is its nature? (jill buried sad, or flature); how did it get there? (primary or secondary deposition); and when was it deposited' (the relationship to other layers and flatures). Posing these questions during excavation ensures that crucial infor mation is not lost once the site is disturbed and allows the archaeologist to determine the site-wide sequence and phases ofdevelopment later in the analysis. Detailed stratigraphic recording and analysis is often seen as time consuming, especially in mitz.'gation excavations, but we will introduce methods currently in use at stratigraphically complex military sites in Ontario that effict rapid, thorough, and accurate recording.
Introduction Archaeological Services, Military Sites, a small group dedicated to cultural resource management Archaeologists in Ontario approach strarigraphy in of military National Historic Sites in Ontario. diverse ways. Some dig in arbitrary spits, then Over the past 24 years we have developed a system record and correlate the stratigraphic profile later to help us answer these inquiries. We do not intend in the analysis. Many excavate stratigraphically. to argue that our method is more effective than any removing each stratum in the reverse order of dep other, but merely want to present how it applies to osition while leaving baulks afterward drawn in our research. profile. Still others use only the plan drawing as a basis for understanding the sequence. Finally. there are some who combine these techniques depend Why Use FOll".? ing on field conditions. Methods for documenting stratigraphy are just as varied. Several use standard We began using recording forms to capture ized, pre-printed forms up to four pages in length, archaeological base data in 1981. Their adoption while others keep a daily log of their findings in a was not withour deliberation. Left with the notebook. Sometimes recording is the responsibil daunting task of making sense out of orphaned ity of a supervisor, while elsewhere each excavator notebooks, penned in prose and often creatively chronicles the excavation. disorganized, we felt that a systematic means of A discussion of the historic factors that resulted recording was necessary. The initial challenge was in this situation is beyond this paper's scope, but it to bring some order to the data without stifling was at least partially born from the "cultural mosa personal sryle and the inherent observations it ic" of American, European, and Canadian scholars brings to the endeavour. Our solution was, we who created archaeological programs in Canada hoped, to marry the best of both worlds. We during the mid-to-late 1960s. However, all looked needed a structured recording form that would to the study of stratigraphy, regardless of method, encapsulate all the requisite information, while at to answer questions about what humans did on a the same time providing enough freedom to site, how they lived, and when it all transpired. allow for in-depth description and interpreta- • The what, how, and when of archaeological (IOn. deposits are cerrainly the basic questions asked by Our recording form had to satisfy several other ,' the Parks Canada Ontario Service Centre goals. Foremost, we wanted it to be a template or I: I !, 1 /l
aide-memo ire that would assist novice excavators Department of Urban Archaeology (DUA), now to focus on the key and essential information the Museum of London Archaeological Services required to document, and ultimately understand, (MoLAS) (Spence 1993). the cultural resources under investigation. Second, it was to act as a frame of reference or ethic. Much of the recording form emphasises interpretation The Lot Summary FOlln and the Primacy of and site formation processes. Consequently, its Interpretation accurate completion challenges our methods and demands thought and attention during excava Central to WRU, MoLAS, and our approach is the tion. The underlying premise is a steadfast belief focus on the "stratigraphic unit." Generally in the importance of stratigraphic excavation and defined, the "stratigraphic unit" represents "any the obligation we have as archaeologists to under single action ... [that] leaves a positive or negative stand the deposits exposed by our trowels. record within the sequence" (Westman 1994:1.2). Efficiency was our third concern. We believed These can have four kinds of temporal relation that having specified data in a structured format ships to other stratigraphic units: earlier, later, would expedite data recovery, provide consisten equivalent, or unknown (Harris 1979a). The strati cy in approach, and concentrate novices' atten graphic unit is referred to as a "context" under the tion on the essential elements of recording. This, MoLAS system (Westman 1994:1.2), but we call it we hoped, would streamline post-excavation "Lot," following Parks Canada conventions analyses and report writing. Fortifications are (DINA 1977). charactetized by modification and change in A "Lot Summary Form" (Figure 1) is filled out response to changing needs. As a result, their when one of the following is encountered: archaeological investigation can often involve 1. Recent sod; identifYing upwards of 100 stratigraphic deposits 2. Occupation level; per excavation unit. Recording forms have great 3. Fill; ly reduced the time required to compile layer 4. Buried sod; correlations and site-wide stratigraphic analyses. 5. Interface; They have also furnished unexpected benefits. 6. Artifact or cluster of artifacts; Because of their structure, it is quite easy to 7. Intrusion; review crew notes to see what essential informa 8. Feature; tion has been recorded and what observations are 9. Natural Strata; lacking before backfilling begins. The forms have 10 Lot extension/baulk; proven their worth during emergency field miti 11. Sample. gation, where time is a premium and distractions Finallv, "Other," can be used when the can unsettle even the most seasoned professional. • The aide-memoire aspects of the forms ensure recorder assigns a lot to a phenomenon he or she that all pertinent data have been noted before believes should receive individual analysis. For services are laid and the heavy machinery gets example, a 25 x 25 em area within a larger down to business. deposit can be designated as a separate lot to The initial influence for our forms came from keep the artifacts from this 25 em square section the Winchester Research Unit (WRU), the aca together, thereby reducing the need to plot them demic environment that prompted Edward Harris individually. to invent what came to be known as the Harris Thus, the first task when filling out the Lot Matrix and develop the "single context sheet" with Summary Form is to define the nature of the lot Lawrence Keen and Pattick Ottoway in the mid- and then in subsequent sections describe its soil 1970s (Harris 1975, 1977, 1979a, 1979b). More type, spatial characteristics, mode of deposition, tecent, though similar, ideas have been adopted and relationship to other deposits. Generally, from techniques begun in the mid-1990s by the most recording forms seek similar information, 72 Ontario Archaeology No. 83/84, 2007
.. - '\:' -: " ;-,:,' -- ,. Parks Canada Ontario Service Centre '-, - Archaeological Services ,- -,
• LOT SUMMARY . . 'I Date Began: 2"t .( , 0+ Crew: Site: \ ':!>lIt ~1I!t ~,.(\C-., *,~ Lot No.: Date Ended: 2~ , 7, 0+ \ SlIt t'" L t. Nature of Lot: Intrusion o Sample o R~ntSod o Buried Sod o Feature o Lot ExtenslonfBaulk ~upation Level o Interlace o ArtifacVClus!er o Natural Strata o Other • Fill a Brief Description: p-b .;~ O( ~ 4.,J 1?'A1\oJ flu. CJ fltttcnttL" , Cl..l.:r -~ Soil Type: Colour: ~G;~S~ 'i!!f'o ... .1 (\.. '(tc+I'%.), 'fa' ..~ t~'t (\~'(t<5lo) M", &~ (\O'(fl..Io{\) ComposlljOn: CMT I\-l.? \07:. ~~ SMt> Compaction: McCGfCAt'G Rock! Particle SiZe (%): \0;" A.~LA«. L-"-'f"S~ S~ t\{E: Eff\!t Spatial Characteristics: , Dimension/Shape and Extent ~cr~ la",1\I't. t. "' .. ""' " o. '3 p , .• Slope!Topography: SI.o\'l!; '1'l> So :r ~ ~~7 .....j pul ""~A ""'''' ~l"'[ Thickness and Range: fp~\),:"'e " .. \tj.Ci<'~9\' IJ $I"T1f A4P 1l{l..l' '\0 ..\"~1:* . Ai"e:M~ lZoe., -u.tl~ Exca~n Method: Hand TroweUad o Shovelled ~eened~4mm o Floated o Not Excavated o Backhoe o Other Mode of Depostion: CONFIDENCE: MODE: o Natural a Primary ~PI'aceo o Multiple Displaced o Unknown "r;; OM OL DURATION: ~crete Event o Accum. Over TIme o Unknown OH ~ OL ARTEFACTS: o De faCIo Il!"I5nmary o Secondary o Unknown ,..( OM OL Interpretive Notes: t1 Ol\).U> D..Itf, CI[M<"°1'<\- M1? >M1l> t::at"on'( ~~al '~..1~ '1¢ off\~' ~U/lCJIs OCC'UY"i'<{I<>.l c, let..o -+1. ~IGIf ,.J ... - 'SI Continued on additional page 0 Lot Relation: US 2." Above; '!.~ I I I I I II I Below: t..'Ib,z.r.. EQual: 2J\ I I I I I I I I Cuts: Cut by; . I ~"} I I I I I I I I I I I Diagnosticl.lmportant Finds: ~QIIC. c.•. ~ sns- G;t j\u , "",SG' , Ck~l\r1f 'E'GI: 1t, .... \ ~...,'"'t\ ~'-S, *CoIt ..!u~ IIf fts~ hlJ> Mt .. ..AI. 'So...i~ ( S"""l: ) ~ Figure 1. The Lot Summary Form (English version) used by Archaeological Services, Military Sites. Developed by j Last and H Cary. Cary & Last For the Record: The What, How and When of Stratigraphy 73 - but our emphasis on the nature of the lot and its record. This is most often achieved by scrutiniz associated formation process (or processes) ing the relationship of each lot to those around it reveals our philosophy that interpretation is fun and constructing a Harris Matrix. As layers are damental to archaeological recording. All addi discovered and added to the matrix, a relative tional data are supporting evidence. chronology for the excavated unit emerges. While many archaeologists prefer to describe a Sometimes this leads to assigning absolute dates deposit solely by its physical characteristics to a lot. For instance, a burn layer uncovered at colour, composition, dimension/shape, and Fort George is known to have been created on a thickness we have found such practice wanting single day May 25, 1813 when a sustained • for our needs. Simply listing a lot's physical traits bombardment by American hotshot batteries lends little to hypothesis building about how and razed to the ground the buildings inside the for when it was deposited. Consequently, we include tification (Figure 2). Narrowing a deposit's origin both natural and cultural site formation process to a specific moment in the past such as this can es under the heading of "Nature of Lot" and pro be achieved only through stratigraphic analysis. vide an area entitled "Interpretive Notes" to cap By placing interpretation so prominently, we ture our preliminary interpretations. override the problem noted in the 1980s by DUA It is also in the latter section that we try to link archaeologists, who found that the absence of pre the deposit to an event in the site's history, based liminary interpretation in their field forms pro on our understanding of the documentary duced only a vague record of what had been • \-~ • 25 May 1813 Ash and Charcoal Deposit Figure 2 The American artillery bombardment ofFort George, Niagara-on-the-Lake, on 25 May, 1813, reducjred the t:k to a s;o;;; derin ru:n. Tan ible remnants ofthis event are marked on the site's archaeology-even at considerable distances om t e . IstOrtC u'. - in s g in the for! ofan ash and charcoal deposit. Top left photograph ofre-enacttnent by Davzd May (Upper Canada Provmczal Manne, gh b D···· \ b tt ";v:htphotoorahh b" Rachel Brooks (Parks Canada, Ontarzo ServIce Centre ColleetlOn). Am erst. urg lVZSlOn/, 0 om '''0' 0" r .J 74 Ontario Archaeology No. 83/84, 2007 to tell an engineer or architect whether or not a unearthed and its significance the excavation <:' (Spence 1993:34). MoIAS partially addressed this deposit is significant or expendable while we are -"-,<-. , ,- digging it, productivity and budgets suffer. --- . with their redesigned forms in the early 1990s .. - " - - (Spence 1993:40), but our Lot Summary Forms Although there are occasions when post-excavation analyses are required to confirm or establish a -- ,. give still more primacy to interpretation. Doing so, '-, .- : , . we believe, mitigates the commonly held view that deposit's historic value, attempting to determine its . '. . pro forma sheets causes excavators to allow "the mode of deposition and evaluate its significance mechanics of the system to impair their intellectu during excavation helps us focus on problematic al method" (Spence 1993:44). By stressing the contexts. mental aspects of digging stratigraphy, we, like Dr. After excavation, knowledge that a deposit is James Tuck who has conducted extensive work at either a fill or an occupation is critical to the the seventeenth-century site of Ferryland, establishment of a Harris Matrix chart, temporal Newfoundland "encourage the excavators to phasing, and the overall interpretation of the site. think about the process that could have been For instance, when dealing with fill, the most responsible for the deposit in which they are dig recent artifact recovered from it provides a ter ging" (Tuck 1996:26). minus post quem, regardless of the number of ear We concede that in-the-field assessments can at lier items found in association. However, the times be speculative. For this reason, we added to same cannot be said of an occupation layer. Since the form a section for "Levels of Confidence," as an occupation is a product of accumulation over well as an "unknown" category, to help denote time, the most recent object retrieved from it which interpretations should be reviewed. No con generally signifies the terminus ante quem of the clusions we make during excavation are beyond stratum rather than its beginning. This also question in the post-field work analysis, but who applies to whether a layer is a primary, displaced, better to assign cultural activities than the excava or multiple-displaced deposit. Additionally, arti tor, at the time of excavation? It is far easier to fact studies are influenced. Regardless of how interpret the nature of the lot and the means of its rare or interesting an artifact collection might be, formation when other units are open and lots an assemblage recovered from a fill will receive found in one unit can be correlated with those of less attention than one found within a buried another. While we stress to all crewmembers the sod, by virtue of its limited interpretive value. importance of looking beyond their own excava When the Lot Summary Form is completed, we tion unit and advise them to note correlations in have a combination of interpretation, sequence, either "Interpretative Notes" or "Lot Relation" sec and physical characteristics. Essentially, it is a mar tions, commonly this task is left to site supervisors, riage between Harris' (l979a) focus on relation who record their observations using supplementary ships and the American school of site formation excavation unit summary forms. Working out a (Rapp and Hill 1998; Schiffer 1976, 1987). Unlike relative site-wide chronology is also achievable at Harris, we do not emphasize the importance of this stage, leading to more encompassing theories every lot's interface; rather, it is the deposit's regarding how the site developed over time. physical composition and its stratigraphic posi In-the-field interpretation also has pragmatic tion that helps us interpret whether it is a fill, a implications. Determining a stratum to be a fill or buried sod, and so forth, and to which temporal a buried sod, and making this explicit from the phase it belongs. start, dictates how the lot will be excavated and studied. For example, fill deposits because they are disturbed contexts can be removed with Never a Scheme Without a Plan greater speed than an in situ occupation level. Such an interpretation also provides Parks Canada Mter writing the Lot Summary Form, the next engineers with data that can be immediately step is to draw the lot's boundaries in plan view included into the planning process. If we cannot (Figure 3). MoLAS uses 1:20 scale for this, but Cary & Last For the Record: The What, How and When of Stratigraphy 75 £t" (}) '31) (i) 1..'1,) -' (;) ~~ ~,~"' Figure 3. Example ofa single-lot plan drawing from Fort Henry National Historic Site, Kingston, Drawn by J. Last, 76 Ontario Archaeology No. 83/84, we prefer 1: 1 0 for smaller pits, as we find it more evolved over the past 200 years (Cary and ," , intuitive. Only the specific lot appears on the 2004: 13-15). Here, the Royal Engineers succes"",' plan; this reduces confusion while emphasizing sively deposited thick layers of rubble about the;; the stratigraphic unit as an individual entity. In site in an attempt to protect and mask the ram-!. order to capture superpositional relationships, we parts of the fort. Other sites, such as Fort.'. rely on abbreviated matrices that include all adja George, have provided insights into land modifi_ ,.' cation since the British occupation and continu- ," ,'; ,.! cent strata. Composite plans are rarely used, ---'·i except when the excavation is completed. The ing after the 1930s restoration (Fox 1996).) -; - unit walls are recorded in profile in 1:10, but if - -- time is limited we may draw 1: 1 by tracing the pro file onto clear plastic sheet, then transferring it to Bringing Home the Stratigraphy paper in the lab. The selection of which wall, or walls, to draw is made on a case-by-case basis; how Once we are out of the field, a thorough site for ever, we record as many as are necessary to docu mation analysis can begin. For this we use the ment the overall stratigraphic sequence. Lot Summary Forms, supplementary notes, pro The practice of drawing profiles is non-nego file drawings, and Harris Matrix to group the lots tiable, be it for test pits or open area excavations. from excavated units into site-wide temporal Profiles are the best graphical representation of phases. Phasing, like lot interpretation, is often the site's formation, and they stand as the only tied to periods consistent with our understand tangible record of past depositional history. ing of the site's history. Commonly, it is estab While a Harris Matrix illustrates the sequence, it lished through the use of the documentary misses the nuances of a layer's thickness, slope, record, although occasionally we can identify and composition (Figure 4). Profiles are also use phases of development previously unrecorded ful for comparative analyses and for on-site pre- that, in turn, inform historic scholarship. This sentatlons• to VISItors.• • dialogue between the historical and archaeologi In open area excavations, a standing baulk can cal record begun with the individual lot and obscure relationships among lots from one unit continued to include the site-wide sequence to another. True to Murphy's Law, a baulk will attempts the "multi-directional approach" to his invariably run across the feature you want to torical archaeology favoured by Deetz understand the most, but there are valid reasons (1993:158), and in doing so, we hope, con to keep it, at least until an occupation level is tributes new insights to the study of British mil reached and the baulk can be drawn and itary life. removed. Because the profile is a physical record, Military sites provide the conditions for a multi although partial, it survives even when a soil layer directional approach, and they require it of us. in the middle of the unit dries out and its bound Because British fortifications are blessed with a aries become difficult to see. It also retains layers wealth of historical records, we can analyze the that were easier "read" in profile than in plan. stratigraphic sequence on a much more fine With the profile, at least a remnant of a some grained level than is achievable on less document times-crucial deposit will remain to be examined ed sites. But while we can narrow down a layer's and preserved. deposition to within a few months, days, or even We maintain this full range of stratigraphic hours such as the burn stratum of Fort recording even when artifacts are not found. George only the sequence can give us this refine Regardless of whether artifacts were dropped in a ment, as the artifacts at best furnish dates to the given area, elements of the historic landscape nearest decade. Such detail allows us to identify usually survive to shed light on archaeological strata associated with the reasons why a site was findings in other areas or at other sites. For exam designated as a National Historic Site by the ple, our study of the fill levels at Fort Henry has Government of Canada. These deposits, and what provided a detailed picture of how the terrain has they represent, are of the highest importance and Cary & Last For the Record: The What, How and When of Stratigraphy 77 Phase \I: Fort Henry National Historic Site Fills and R';:c(.;!l[ Sod. Kingston, Ontario c. late 20th C.:nlury Sub-operation 131H16F .:. 1970$ Trcilch (ut Stratigraphic Matrix and East Wall Profile Phll~C IV; , Harris Matrix Officcr~' B;uracks IkstrtrClj,m , and Wt:~t Range Commissariat of QUancrs CDI1Slrl,lctiOn. 184 J Sub-operation I , @ , , CJO ~ f)ji t;>- c7 d' , ~ Gravel and clny loam ,- , oc 50 em 1m Phase II: " Ot1ict'rs' Barr:u.:k-" Wull Construction. Fills and Code Explanation Occupation. c. IS:!O-183:! ~mF2~ / ~ She l\url'lber LOI Number Sub-operatiotl South Wan (]fc.1820-41 (SXc;\Vlllin!\ Unin Nllm~r OUicers' Barracks _--,1- Dr;,wn by 11. Cary r"Jrks Ca.nuda Archaeol(]gi .. al Sc~ices L Phase I: Nuttlntl Limestone Bedrock Figure 4. Example ofa stratigraphic profile and accompanying Harris Matrix from Fort Henry National Historic Site, Kingston. Drawn by H. Cary. must be protected and presented to the public. Conclusion: Benefits of the Lot Summary Determining which resources are of national or Form regional significance also has ramifications for our collections management strategy in that it Our level of recording is easily perceived as time provides guidelines for their future storage and consuming and at times excessive, but we present study. that in most cases it is in fact faster and more Phasing, like lot interpretation, is not a one consistent. The British model from which it time exercise and can involve re-evaluation, came was specifically designed to speed up data refinement, and rethinking. Because we return to recording without sacrificing accuracy (Spence sites continually, sometimes in the same year, the 1993:26). The set of checked boxes on our Lot stratigraphic intelligence we have gained at Summary Forms, like the reminder lists on the Ontario's military sites allows us to effectively and MoLAS forms, serve as mental prompts to ensure efficiently assess what is significant and impor that the same information is recorded for all tant. In turn this often speeds excavation, record deposits, features, or cuts regardless of how ing, and subsequent interpretation, all of which hot, cold, wet, frozen, or pressured the excavator are primary concerns to field archaeologists. might be. 78 Ontario Archaeology No. 83/84, 2007 Research Division, Parks Canada, Ottawa. , , , Our single-lot method is also advantageous -',-,;- -,-,8' - - --'," because it can be adapted to any site regardless of Ms. on file, Parks Canada Ontario Service - --,,'- Centre, Cornwall. " ,,-'- type, affiliation, or age. We do stress, however, Cary, H.C., and J.H. Last that knowledge of site history, as discussed above, 2004 Archaeology at Fort Henry: The Advanced is mandatory for interpretations to be formulat Battery. Ms. on file, Parks Canada Ontario ed with confidence. Expedience and precision are Service Centre, Cornwall. often achieved by making the excavator responsi Deetz, J. ble for documentation. The well-trained field 1993 Flowerdew Hundred' The Archaeology of a worker who removed the deposit is the most Virginia Plantation, 1619-1864. University . qualified to describe its characteristics, freeing up Press of Virginia, London . the supervisor to move among excavation areas Fox, K. with the knowledge that a standard set of data are 1996 Surfing Through History: Illustrating the Structural History of Fort George with Surfer© being recorded. For large mitigations, this is par for Windows©. Ms. on file, Parks Canada ticularly important, because a single principal Ontario Service Centre, Cornwall. investigator simply cannot record all of the Harris, E. e. recovered elements simultaneously. 1975 The Stratigraphic Sequence: A Question of Over the past two decades, the content and Time. World Archaeology 7(1):109-121. detail of our Lot Summary Forms have slowly 1977 Units of Archaeological Stratification. evolved, but what has not changed is our under Norwegian Archaeological Review 10(1- lying belief in the primacy of stratigraphic exca 2):109-121. vation, matrix analysis, and the interpretation of 1979a Principles of Archaeological Stratigraphy. modes of deposition. Given our mandate and the Academic Press, London. 1979b The Laws of Archaeological Stratigraphy. complex nature of the sites under study, we have WorldArchaeology 11(1):111-117. found that the use of Lot Summary Forms, Rapp, R., and e.L. Hill beyond acting as an aide-memoire, help to guide 1998 Geoarchaeology: The Earth-Science Approach to our interpretations in and out of the field. While Archaeological Interpretation. Yale University we acknowledge that our Lot Summary Form is Press, New Haven. not the end-all for archaeological recording, it Schiffer, M.B. does provide an assurance that basic information 1976 Behavioral Archaeology. Academic Press, New is captured in a thorough, consistent manner. York. 1987 Formation Processes of the Archaeological Acknowledgements. Many thanks to Eva Record. University of New Mexico Press, Albuquerque. MacDonald and Dena Doroszenko for granting us Spence, e. the opportunity to join this interesting and impor 1993 Recording the Archaeology of London: The tant forum, and to Edward Eastaugh and Wade Development and Implementation of the Catts for their insightful comments on earlier drafts DUA Recording System. In Practices of of this paper. We are also indebted to the OAS Archaeological Stratigraphy, edited by E.e. reviewers, whose ideas and suggestions helped Harris, M.R. Brown III, and G.J. Brown, strengthen the prose and intent of this paper. pp. 23-46. Academic Press, London. Tuck, lA. References Cited 1996 Archaeology at Ferryland, Newfoundland 1936-1995. Avalon Chronicles 1:21-42. DINA (Department of Indian and Northern Affairs) Westman, A., ed. 1977 Parks Canada Archaeology Manual Volume 1: 1994 Archaeological Site Manual. Museum of Excavation Records System. Archaeological London Archaeological Service, London.