Geological map and memoir collections as a source of data on the quality of the rock record

1
Geological map and memoir collections as a source
of data on the quality of the rock record

• Alistair J. McGowan and Andrew B. Smith
• Department of Palaeontology, Natural History
  Museum
• alandchristine_at_googlemail.com

2
Talk structure
Sepkoski (1979)

• - Problem Separating genuine increases/decreases
  in diversity through time from variation in
  sampling.
• - Requires a means of assessing variation in
  sampling effort. What measure(s) should we use?
• - Using web and GIS tools to quantify changes in
  rock availability
• - Getting the public on board

Benton (1993)
3
Framing the data, fixing the results?
Global perspective (When?) -Encourages top-down
explanations of biodiversity patterns -
Palaeontological data treated as a series of
points though time. - No spatially explicit
thinking/analyses
R. A. Rohde (Creative Commons)
Local/regional perspective (When AND
where?) -Encourages consideration of a broader
range of explanations - Palaeontology in
4D -Spatially explicit analyses become standard
Kidwell and Holland (2002)
4
The geological record Bias in four dimensions
Time
Space and relative sea-level change
Palaeogeographic shifts
Mork et al. 2000
Differential sampling of habitats and destruction
of records by geological processes
5
Proxies for rock availability per geological
interval
Number of formations Indicate diversity of
sedimentary habitats and, by extension,
ecological habitats. However, formations are not
consistently defined internationally
http//strata.geol.sc.edu/exerices/seismic/exercis
e3-final-report.html
6
Hurricane Cliffs, Utah
Calcarenite dominated succession marked
lateral variation in bed development
intraclasts abundant in lower beds
7
Beaver Dam Mountains, Utah
Mudrock dominated, with occasional calcareous
shell beds more distal setting than Hurricane
Cliffs
8
Proxies for rock availability per geological
interval
Outcrop Area Amount of rock available to sample,
but fossils can be very patchy in their
distribution
GIS-based analyses are promising Can overlay and
interrogate many types of spatially explicit
data E.g. US census data used to test if more
fossils are found in more populous areas
Uhen Pyeson 2007
9
Proxies for rock availability per geological
interval
COSUNA charts (Peters 2005)

• Records information on rock deposition at the
  basin-level scale
• Main charts are aggregates of
• section and borehole data from
• 100km2 areas around each point
• Contains considerable amounts of
• subsurface data.
• Useful for estimating total amount
• of rock deposited
• BUT does not account for the
• relative lack of fossils collected from
  subsurface deposits

3dparks.wr.usgs.gov/nyc/images/fig114.jpg
10
Proxies for rock availability per geological
interval
Number of collections Sampling effort by
collectors, but does not indicate
geographic/environmental spread of sampling or
intensity of sampling effort
Localities sampled in Early Triassic Virgin
Limestone of Utah
11
Proxies for rock availability per geological
interval
Number of maps with outcrop Provides information
on extent of outcrop. .
Hard labour in NHM geological map library
Maps as sampling quadrats (Image NBN Gateway)
12
Key advantages of linked map and memoir series

• Map/memoir combinations mimic of the discovery
  process of fossils.
• Data on multiple formations and
  terrestrialmarine units ratio
• Record of whether a unit is fossilferous within
  EACH map area
• Additional insight into the age and environment
  of the outcrop(s) of a unit in a particular area

13
Construction of species-(rock) area models (Smith
McGowan 2007)
Apply resulting equation to rock time-series in
correct order and compare to Sepkoski curve
Independently order diversity and rock
time-series from low to high
With use of digital map data we can examine a
broader range of variables
14
Using BGS Digimap and other online resources
Bedrock
Drift overlay
15
Combining data types and information
Map built from 1100000 series shapefiles in
Arc Explorer
Ballyadams and Aghmacart Formations
http//www.gsi.ie/
Example using the Geological Survey of Ireland
1100000 map data
16
Extent of Aghmacart and Ballyadams Formations
Ballyadams Formation (Carboniferous crinoidal
limestone)
Aghmacart Formation (Carboniferous dark shaly
micrite, peloidal limestone)
17
GIS-based metrics

• Aghmacart Fm
• sheets 2
• polygons 12
• Max 46.5km2
• Min lt 1km2
• Mean 13.8km2
• Total area 165km2

• Ballyadams Fm
• sheets 4
• polygons 57
• Max 171.3km2
• Min lt 1km2
• Mean 13.5 km2
• Total area 767.8 km2

18
Integrating palaeobiodiversity and geodiversity
data within NBN
Museums and geological surveys provide taxonomic
expertise and safeguard collections, but are too
understaffed to run routine identification and
much of the data entry. So....
19
Citizen science, regional recorders and
(palaeo)Biological Recording
Expected species richness
Tetrads with Oystercatcher
Tetrads with Blackbirds
20
Conclusions

• Geological maps and memoirs (and the archivists
  who curate them) are important resources for
  quantifying the relationship between rock
  availability and changes in diversity through the
  Phanerozoic.
• Digital maps offer new analytical capabilities
  that should be exploited to bring analyses of
  palaeobiodiversity into step with modern
  ecological techniques.
• A research area that could potentially become a
  citizen science project in Earth Sciences to
  match biological recording projects for extant
  taxa.

21
Acknowledgments

• Meeting convenors
• Andrew Smith, PI on Leverhulme
• Michael Benton, University of Bristol
• Kenneth Johnson, NHM
• Jon Todd, NHM
• Shanan Peters, University of Wisconsin-Madison
• Hellen Pethers, NHM Earth Sciences Library