Sedimental Values: Digging In to La Brea’s Past

In the middle of the enormous urban environment of Los Angeles, California sits the La Brea Tar Pits, one of the richest and most famous late Pleistocene (last Ice Age) fossil sites in the world. Due to the geography and geology of the L.A. Basin, oil has accumulated on the surface becoming a sticky “tar” trap for millions of plants and animals over the past 50,000+ years. Paleontologists have been collecting fossils at the site from “Pits” since 1913, cataloging them into archival ledgers for the past hundred years.

Buried within typed pages of fossils and geology samples are data about exactly where and how specimens were found in the ground. Since excavation is a destructive process it is important to record everything about a specimen or sample that you are about to remove. Pit 91 was initially divided up into 3 foot x 3 foot grid squares, 6 inches deep, each one given a unique field number. Within each of these grids, hundreds of fossils were discovered, each one requiring exact measurements. Depending on the bone, a set of criteria were established to indicate what each data point referred to. Here is a dire wolf femur as an example:

Although you will see many abbreviations in these papers, the most common are the three that are on almost every record (and which we're asking you to transcribe):

BD = "Below Datum" ("Datum" is in reference to a datum plane 172 feet above sea level)
N = "North"
W = "West"

These measurements help researchers situate the specific fossil within the overall geographic space of the Pit.

One of the biggest challenges for museums in the 21st Century is the digitization of their collections. In the past decade the Collections staff and volunteers at La Brea have been busy entering paper records of excavation into the Museum’s database, with the goal of getting all cataloged records (~600,000) in an electronic form by the end of 2020. However, this is only a fraction of our collections. Many more were collected but are not prepared or cataloged yet. Having digital records not only helps management of such an enormous collection, but also makes it freely available for global research. Held in the public trust, museum collections contain vital information connecting our past, present and future. Imagine a world where the possibilities for Museum education, engagement and research are just a click away!

Sedimental Values will capture 40 years of fossil field data from Pit 91, allowing the Museum to plan for preparation and curation of a collection numbering in the tens of thousands or maybe more! It will allow our curators, students and visiting paleontologists to ask research questions about Paleoecology and target their efforts on particular samples or specimens. Research has already shown that Pit 91 offers us a unique glimpse into prehistoric LA with over 600 species of plants and animals noted. We know there are more species to be discovered. This site contains hidden secrets about past climates and may provide us with an important baseline with which to understand our current biodiversity.

This research is being conducted as part of the Collections, Heterogeneous data, And Next Generation Ecological Studies (CHANGES) project at the University of Michigan.

Image Credit:
Shaw, C.A. (1982), Techniques Used in Excavation, Preparation, and Curation of Fossils From Rancho La Brea. Curator: The Museum Journal, 25: 63-77. doi:10.1111/j.2151-6952.1982.tb00583.x