11 December 2011

Our Blog is moving!

Hello fellow fossil enthusiasts and asphalt-saturated bone from the Ice Age lovers. The Excavatrix as you know it today will no longer be the site for our updates. To check out what's new with fossil digging and processing here at the Tar Pits, please refer to our brand new tarpits.org website (Yay!) that's launching tomorrow, 12/12. The new "Blog" can be found by clicking "Blog" at the far right of the website's top page menu.

The Excavatrix at blogger.com will still be available to view old posts at this time.

I'd like to give a shout out to Andie, the awesome creator of The Excavatrix at blogger.com and hope that you all will enjoy the new tarpits.org website!

20 August 2011

We opened another box!

This is box 12. It contains the next deposit from Project 23 to be excavated.
Box 12

Deposit 12 facts:

  • 10,000 pounds (pretty small compared to the others)
  • Sits at north-east side of compound, front row along the north fence
  • Excavators will be able to stand or sit at its sides
  • No indication in notes as to what it may contain
  • associated with 6 spoils buckets
Under the white tarp, the deposit is seen wrapped in plastic with supportive foam and fill cushioning its sides

Brain foam, Ew!
Brain foam


It will be an ex-home to mud daubers
Mud dobber
and paper wasps
Paper wasps in a bad place

We cleared away the plastic and scanned the surface for fossils
Laura checks the deposit surface for fossils

This is it from the box so far, some very weathered large bone frags:
This is bone (very weathered)

Before setting grid lines, we need to consider that the box's current orientation to north is different from its original orientation
Preparing for gridline orientation

Measurements written on the side of the box indicate its orientation from north as it was in the ground. The box north line is determined from these measurements.
Finding North


The top board is cut down from one side and it's ready for digging


Karin found the 6 deposit 12 buckets from the shed and so far they have been more interesting than the box, containing bones from various large mammals


This is a sabertoothed cat tibia that had been broken in three pieces


The bone is lighter in color and more brittle than our normal asphalt protected bones


And upon closer inspection we see crystals growing on the cancellous tissue


Also, a horse tooth!


There are also fragments from other very large animals. I don't know which sides of the deposit they all came from, we will have to see as we go through the box, hopefully, maybe, where the rest of that cat, horse, and others are!

01 June 2011

How to Screen Wash Project 23 Matrix

Over 2000 buckets of matrix produced from Project 23 thus far and what to do with them? Reduce! Our matrix contains a lot of non-asphaltic sediment that can be washed away. Over past months Excavators have been working on a new system for screen washing, with major organizing and tool/equipment building done by Karin.

First, we choose buckets that have a lot of fine non-asphaltic sediment and soak overnight:
soaking matrix

We then scoop muddy squishy matrix from its bucket into a specialized bucket with a 20 mesh (size used for micro-fossil sorting) screen on the bottom (that Karin made) and swish and break
down the fine dirt that washes into tubs of water (that Karin made, sitting on a wooden platform that Karin made)
the wash station


Between washings, the bottom is cleaned. It is a rather enjoyable process bringing us back
back to our mud pie making days.

removing silt from matrix

The matrix dries on screens and then is bagged. Sometimes visible microfossils are "high graded" into a capsule within the bag. One rather large recent surprise was a Nothrotheriops shastensis patella in matrix from Box 1. It's the first Shasta ground sloth found in Project 23!

bagging dried matrix

A five gallon size bucket of matrix reduces down to about a gallon size bag of matrix that will later be degreased, and then we re-use buckets - yay!
from bucket to bag

In other P23 news....

Box 14 had a bit of a make-over with our use of one of the fancy canopies from Media Day

Little Timmy's left lower mandible shows up near a disturbed part of the deposit

An herbivore (probably bison) maxilla is revealed in Box 1
P23 1 B-1 L-6 grid progress

And in the lab, Herb found two elements (occipital horns and maxilla) from a coastal horned lizard in Box 14 while sorting matrix from a block of asphaltic sand containing many small delicate bones. These are the first horned lizard bones found since 1929 in Pit A, and only the second individual ever identified at Rancho La Brea.

27 March 2011

Cleaning and the Media

Spring cleaning started early this year with Pit 91 glopping and maintenance.
Since it is a dirty job, Laura donned our recently donated fishing waders/frog suit

Pit 91 Drama

Michelle did some reverse basting to remove water sitting
around the fossils.

Removing water

Here Karin gets those tough to reach support beams with
her vacuum hose extender handle to suck up the dirt
and leaves that Michelle bravely swept to the edge.
Extended vaccuming

Michelle showcases our new Pit 91 decorations


And here's an ancient grid number I found on the wall!
Pit 91 grid number

Our even bigger excitement than cleaning Pit 91 in March was Media Day.
We prepared the compound and Box 1 and 14 for numerous visitors. Both
large fossil deposits from these boxeswere well exposed and shined and the
reporters were given direction on where to stand.
Box 1 ready for visitors

Along with showcasing the boxes, we also had a table of fossils in the compound
including an unprepared large tree branch, some prepared Little Timmy elements
and 6 prepared saber-toothed kitten radii.

photo by Nola Milner

In the lab a table was set up to show off Clyde's skull and mandible, juvenile bison from Box 7B, saber-toothed kitten mandibles and maxillae, elements of Fluffy, Donatello, oak leaves, beetle eaten pine, and millipede.


The fishbowl lab showed off the recently opened skull of Zed and here's the
Project 23 crew standing around him at the end of the day

John and Shelley gave a speech to numerous reporters about what has been
discovered in Project 23 for the last two years and then the reporters were
released to the table, boxes, and lab to interview us.

Laura on TV
photo by Nola Milner

Here are some links to articles as a result:

LA Times (Blog): http://latimesblogs.latimes.com/unleashed/2011/03/la-brea-tar-pits.html

La Opinion (Print): http://www.impre.com/laopinion/noticias/la-california/2011/3/10/mamut-cuenta-la-historia-de-la-244025-1.html#commentsBlock

Trekaroo (Web): http://blog.trekaroo.com/2011/03/14/monday-madness-win-a-family-four-pack-of-tickets-for-the-page-museumla-brea-tarpits/

URCA (Radio): http://www.yourcaliforniashow.com/radio-links/prehistoricbonesnearlosangeles-homebrewing101-andmuchmore

LA Weekly (Web): http://blogs.laweekly.com/informer/2011/03/la_brea_tar_pits_new_fossils.php

KPFK (Radio): www.hearinthecity.org

Plus, close to 300 media outlets ran the AP story from when we were interviewed two days before Media Day


Here are the excavators looking our best on Media Day.

photo by Nola Milner

Continuing on with cleaning, last week we poked through the collection of animal skeletons that are in various states of decay in the "monkey shed." With eagerness and sometimes slight reluctance, Michelle took an inventory to show her forensic anthropology classmates who might assist in preparing them for storage in our modern comparative collection in the lab.


Karin found a shy new friend

And another....the bear labelled "Bozo"IMGP0802

and an apparently to Michelle, an absurd pelican beak

The fun never stops here, even with the recent torrential rain.

During lunchtime the canopy over deposit 14 collapsed from the weight of water

We also brought out the warm and cozy Tyvec suits that Bruce donated

And if you need a fossil fix (aside from looking at our great work in pictures taken by the media), here's a broken bison rib in box 14 currently exposed. At the top left there is a bison sacrum.


And check out our new scaffolding next to Box 1, complete with canopy!


We are ready for spring/summer digging!

31 January 2011

New Staff Lounge

This was Box 7A in 2009:

Now it is these roughly 600 buckets lining the interior fence:


The floor and wall boards were cleaned up, many of them saved, and now we have a nice new staff lounge:


Here's one of the 7A board lurkers:

Now that 7A is done we are spending more time on Box 1 again. Christina and Laura
found a dire wolf baculum!


We are also working on exposing more of the large bone deposits in boxes 1 and 14 and making them pretty to show off on our upcoming media day.

In a certain area of box 14 I have been finding a few bones with a colorful oil film.
I don't recall having encountered this before in my Project 23 digging experience.