How did SLTT go about its work?

SLTT conducted its activities without dedicated salary and without a dedicated travel budget. As a result, face-to-face meetings generally were not possible, and SLTT members boot-legged time from their agency science projects. The majority of SLTT interactions have been by email and by conference calls. Both internal and external evaluation of science-language concepts was facilitated by a web-conference site (archived) that stimulated discussion of philosophical and operational issues.

Development of philosophy and guidelines

Early in its deliberations SLTT had to figure out what exactly we were going to do, what was the scope of our assignment, how we would reconcile various geological traditions and perspectives represented by the SLTT group and their constituents, and how we would develop a consensus science language. To facilitate this discussion, the SLTT chair (Matti) periodically issued memoranda that stated guidelines, summarized deliberations, and ameliorated differences of approach. Some of these memos are archived here:

• Kickoff memo (04/03/2000)
• Tasks (04/20/2000)
• Action-plan (12/01/2000)
• Consolidated versus unconsolidated (02/15/2001)
• Clarification of objectives (03/14/2001)
• Relationship between SLTT and NACSN (03/20/2003)

20-queries exercise

SLTT’s first task required each committee member to submit twenty queries to a hypothetical geologic-map database. The 20-queries exercise had two purposes:

1. it served as a proxy for a requirements analysis that might be conducted among users of digital geologic-map data in order to determine how such products are used, and how the geologic data might be structured and organized from the point of view of concepts, content, and vocabulary;
2. it was a means of getting each SLTT member to think about the science concepts that might be embraced by geologic-map databases, along with the issues and problems associated with naming, relating, and querying information about geologic materials and geologic structures.

Results of the 20-queries exercise revealed that database-users were interested in a broad range of geologic concepts and database targets. These ranged from (1) academic queries related to the lithology, genesis, geometry, and age of geologic materials and structures, to (2) pragmatic queries targeting what information geologic-map units and geologic structures contain about natural resources, fluid transmissivity (ground water and hydrocarbons), geologic hazards (swelling ground, landslides, earthquake-induced ground-shaking), and land-use planning (landfill siting, ground-water recharge, commercial and residential development, infrastructure siting). SLTT’s task was to develop science language to facilitate this broad range of potential database queries.

Archived here are the results of the 20-queries exercise:

• SLTT 20-queries master list
• SLTT 20-queries, list of vocabulary terms

Results of the 20-queries exercise were passed along to the NADMSC Data Model Design Team (DMDT) for analysis and (especially) to ensure that science concepts emerging from the SLTT process were considered by DMDT as it developed architecture for a standard geologic-map data model.

Separation into subgroups

Early on, SLTT decided to split into subgroups organized around major classes of earth material:

• Plutonic subgroup (R.L. Kistler and D.M. Morton, co-chairs)
• Volcanic subgroup (S. Ludington and R. Christiansen, co-chairs)
• Metamorphic subgroup (J.W. Horton and S.M. Richard, co-chairs)
• Sedimentary subgroup (J.C. Matti and G.A. Weisenfluh, co-chairs)
• Surficial-materials subgroup (R. DiLabio, D.M. Miller, C. Olson, D.R. Soller, and A. Bolduc, co-chairs).

Ultimately, SLTT recommended to NADMSC that the surficial and sedimentary subgroups merge into a single group, based on three factors:

1. unconsolidated surficial materials are sedimentary in origin;
2. the lithology, physical properties, genesis, and geomorphology of sedimentary and surficial materials are identical;
3. scientific perspectives and geologic-mapping experience in the two subgroups complemented each other and provided insights beneficial to both groups.

NADMSC sanctioned this recommendation, and the combined sedimentary and surficial subgroups have worked together to develop a single body of science language for unconsolidated and consolidated sedimentary materials.

The SLTT chair selected subgroup co-chairs based on the following criteria: geologic-mapping experience, expertise in their science field, and knowledge of their agency’s role in producing or using geologic-map databases. Subgroup co-chairs reflect a range of American and Canadian constituencies and Federal and State perspectives.

Iterative science-language development

Using the 20-queries exercise and building upon the four BGS classification documents, the SLTT subgroups iteratively developed science-language schemes that were exchanged by email among subgroup members. This process continued from about September, 2000 through May, 2004.

Internal SLTT review

After each subgroup completed a consensus classification of earth materials, subgroup documents were submitted for SLTT-wide peer review. This review was intended to ensure uniformity of philosophical and operational approach throughout the SLTT science-language process.

NADMSC review

Following internal SLTT-wide peer review, SLTT science language documents were forwarded to the NADMSC for evaluation and review for consistency, for geopolitical sensitivity, and for compatibility with the data-model architecture being developed by the DMDT.

Community-wide peer review

With NADMSC approval, the SLTT documents now are under final revision, and will be released on this website for broad peer review within the North American geologic-mapping community.