Aracaria Seed Cones

Object/Artifact

-

Crater Rock Museum

Name/Title

Aracaria Seed Cones

Entry/Object ID

07.58.07

Description

Assemblage Zone: fluvial sediments Chemical Composition: Si O2 Crystal System: Hexagonal Description: Genus: Acaucaria Species: Mirabilis Common name: Aracaria Seed Cone Age: Jurassic Location data: Cerro Cuadrado Petrified Forest, Santa Cruz Province, Patagonia, Argentina South America Description: A whole araucaria seed cone, colored tan or pinkish-beige from the rhyolite tuffs Type of Fossils Present: Plants Fracture: conchoidal Grain Size: Fine Hardness: 7 Quartz Lithofacies: rhyolitic tuffs Luster: Glassy Occurrence: Even though these cones grew in the Jurassic over 100 million years ago, some of these cones still display excellently preserved petrified seed kernels. Whenever the forests were buried and then preserved under volcanic ash, petrified wood and seed cones can be found today. Ash spewed from volcanoes and buried vast forests about 160 million years ago (during the time of the dinosaurs). Minerals from the ash seeped into the cones, injecting them with color as they gradually turned to stone. Pressure: Moderate Rock Color: Medium Rock Origin: Post-depositional Rock Type: Sedimentary Specific Gravity: 2.6 Surface Process: Not apparent Temperature: Low to moderate Texture: Microcrystalline Variety: These fossil pine cones and fossil limbs are from Araucaria and Paraaraucaria trees. They exhibit incredible preservation and exquisite detail. Under the family of Araucariaceae, the now extinct specie of Araucaria mirabilis covered the areas of earth during the middle Jurassic Period about 135 to 180 million years ago. Nowadays, the best preserved araucarian forest in the Cerro Cuadrado Petrified Forest in Patagonia. Tree trunks found at the site proven some of these trees stood some 100 meters or 329 feet tall. These ancient giants were cut down by a series of volcanic eruptions, covered by ash, and preserved. Over time, water seeped into the deposits, digesting the ash, and depositing minerals that resulted in the panoply of colors as they gradually turned to stone. Hence, the place is very unique for its beautifully preserved petrified Araucaria mirabilis cone that can’t be found anywhere else around the world.

Collection

Petrified Wood Collection

Acquisition

Accession

07.58

Source or Donor

Petrified Wood Collection

Acquisition Method

Donation

Other Names and Numbers

Other Number

Other Number: 2007.58.07

Dimensions

Width

2-1/2 in

Depth

3-3/8 in

Length

2-1/4 in

Dimension Notes

Dimension taken at widest points

Location

Location

Shelf

3rd right on left, 3rd right on left

Wall

East

Room

Wood room

Building

Mentzer Hall - Petrified Wood Room

Category

Permanent

Moved By

Catherine Boyd

Date

March 6, 2008

Location

Container

Center

Drawer

3rd Shelf

Shelf

Right

Cabinet

Case #104

Wall

East Wall

Building

Mentzer Hall - Petrified Wood Room

Category

Permanent