1. Desk-based Assessment & Deposit-centred Approach, worked example:
M25 junction 2 improvement
Francis Wenban-Smith
Heritage in Practice CPD course
Birkbeck, University of London
15th September 2017
CAHO-Contracting
Palaeolithic pre-construction
archaeology
Department of Archaeology

2. Worked example: M25 junction 2 improvement - introduction
CAHO-
Contracting
Real-world example
Demonstrate general approaches
Wider view
- deposits, landscape
- Palaeolithic remains
- general potential
Closer view: Palaeolithic Character Areas
- map + attribute table
- deposit character
- Palaeolithic remains
- more-specific potential

3. Wider view: landscape and geology
CAHO-
Contracting
Wider view: landscape and geology
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4. Wider view: landscape and geology - keys
CAHO-
Contracting
Wider view: landscape and geology
- keys
Drift
Solid

5. Wider view: proforma, DBA output 1: - deposits
CAHO-
Contracting ,
Drift
- Head
- Head Gravel
- Alluvium
- Dartford Silt
- Taplow Gravel
- Lynch Hill Gravel
- Boyn Hill Gravel
- Black Park Gravel
- undifferentiated terrace gravel
- Slopewash [Terrace?]
- Overbank flooding, intertidal, marsh
- Aeolian/loessic? Alluvial? Slopewash?
- Fluvial: high/low energy?
Channels? Alluvium? Land- surfaces?
- residual surface finds, or from un- mapped Pleistocene deposits [or maybe a mistake in the data]
- Gentle burial? Derivation?
- More vigorous burial? Derivation?
- High integrity, low disturbance
- High integrity, low disturbance?
- Varied disturbance: probably generally low, occasionally more- disturbed and reworked, and occasionally totally undisturbed
- need to consider most-likely deposit type
Solid
LC - London Clay
LMB - Lambeth Group
T - Thanet Sand
UCk - Upper Chalk

6. Wider view: Palaeolithic remains - HER, SRPP (map)
CAHO-
Contracting
Wider view: Palaeolithic remains
- HER, SRPP (map)
3km radius
records of known find- spots: A, E, G
HER=SRPP?
SRPP a bit awkward
Has out-of-date landline & geo- mapping
Nonetheless, good source:
- prior to 1993
- primary references

7. Wider view: Palaeolithic remains - HER, SRPP (site information)
CAHO-
Contracting
Wider view: Palaeolithic remains
- HER, SRPP (site information)

8. Wider view: Palaeolithic remains - map sites onto deposits
CAHO-
Contracting
Wider view: Palaeolithic remains
- map sites onto deposits
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Accurate, Estimated
General
Important
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9. Wider view: general potential - collate site info, DBA w-i-p
CAHO-
Contracting
Wider view: general potential
- collate site info, DBA w-i-p
not a formal “output”
my working method, w-i-p
add site names
add/investigate key primary references
relies on accuracy of HER info
need to second-guess most-likely geological provenance
“Undiff. T” = “Plateau Gravel”

10. Wider view: general potential
CAHO-
Contracting
Wider view: general potential
- collate site info by deposit, consider process/potential
DBA - output 2 - Wider view of deposit types and associated Palaeolithic remains
application of Deposit- centred Approach
problem of “most- likely” vs “maybe”
extrapolate info from wider area into site PCAs
“Absence of evidence..” from previously- uninvestigated deposits

11. - site location, topography
CAHO-
Contracting
Narrow view, PCAs:
- site location, topography

12. CAHO-
Contracting
Narrow view, PCAs:
- geo overlay

13. - geo overlay + PCAs layout
CAHO-
Contracting
Narrow view, PCAs:
- geo overlay + PCAs layout

14. - PCAs information and attribute summary
CAHO-
Contracting
Narrow view, PCAs:
- PCAs information and attribute summary
various discussion points
models of site formation in terraces
addressing uncertainty?
following known high potential, or investigating whether potential
problem of addressing rare but important remains:
- the “till” question
- the “London” question
- general potential