Download Fossil Field Trip Pre Lab 2016

The Fossil Field Trip: December 2016
Objectives:
Students will know how to properly collect, classify, and prepare fossils for display. Students will use qualitative and
quantitative data to describe and identify their fossils, and determine in what time period the organisms that formed
their fossils lived, using a field guide.
Building a collection:
The fossils you collect in the field are for the most part, common, and could potentially even be found in your yards. There are
certain fossils you can expect to find, such as fossil oyster shells, brachiopods, echinoids, ammonites, and many mollusks. There
are certain fossils you will not find, either, because the area where you will be excavating Friday was a shallow ocean during the
Cretaceous Period. You would not expect to find any trilobites there, because trilobites were long extinct by then.
Pre-Lab Background Information
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Precambrian
Geologic Time in Texas
The Precambrian: Precambrian rocks can be seen today in the area commonly referred to as the Llano Uplift of central Texas
and in far western Texas. Fossils are rare to non-existent in these metamorphic and igneous rocks. See if you can locate it using
the legend above as your guide. It is in the central region of Texas, and is orange in color.
The Paleozoic: As you can see in the legend, Paleozoic rocks are well represented in Texas. Paleozoic rocks are represented by
the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods. The presence of Cambrian sandstones
indicates that sediments were brought into the sea from land areas to the northwest of the state. The limy sediments (which
have a great amount of calcium oxides…CaO) deposited farther out to sea preserved the remains of trilobites, brachiopods,
bivalves, sponges, and other invertebrates.
This deposition of limy sediments continued through the Silurian and Devonian; however, fossils are rare in the Silurian rocks and
most Texas Devonian rocks are subsurface and can only be seen in drill cores, which are columns of material removed from the
Earth’s depths by drilling. Rocks of the Early Carboniferous are not exposed at the surface in Texas, while rocks of the Late
Carboniferous are well exposed in north-central Texas, and fossils are quite common in these outcrops. Try to locate these late
Carboniferous outcrops on the map.
During the Permian, north-central Texas was an area of changing environments, where shallow marine waters gave way to lowland
coastal areas. Extensive Permian salt and gypsum deposits indicate that evaporation rates were high, and the red beds in this
region contain an abundant vertebrate fossil record. An ancient reef system preserved in the Guadalupe Mountains of far
western Texas is evidence that the sea still covered that part of the state. These rocks are rich in marine invertebrate fossils as
well as rare vertebrate fossils, primarily sharks. Try to find these Permian outcrops on your map, to determine where these rare
fossils may be found.
The Mesozoic: Mesozoic rocks are common in several parts of Texas. The Mesozoic Era is represented by three Periods, the
Triassic (earliest), Jurassic (Middle) and Cretaceous (latest). Triassic sands and shales were deposited as part of a large river
system. These rocks contain a well-documented vertebrate fossil record that includes numerous reptiles and amphibians. These
shales, however, are rich in marine fossils, not terrestrial. Rocks of the Jurassic Period are virtually absent at the surface in
Texas, but can be seen in a few small exposures in far western Texas and in subsurface drill cores. The Cretaceous was a time of
fluctuating sea levels in the state. The shoreline shifted back and forth many times, leaving behind a record of both marine and
non-marine environments. These rocks contain a rich fossil record including dinosaurs, other reptiles, amphibians, birds, fish, and
mammals. As you can see from the map, the area where we live and will be going on our fieldtrip has largely Cretaceous rocks at
the surface, and should then contain Cretaceous fossils.
The Cenozoic: The Cenozoic Era is represented in Texas with the two Periods of the Tertiary (earliest) and Quaternary
(latest…current). During the Tertiary, extensive volcanic activity poured lavas across the landscape in far western Texas;
however, much of the modern High Plains and Texas Coastal Plains are covered by rocks formed from sediment washed down from
the rising Rocky Mountains to the northwest. These sedimentary rocks contain a rich vertebrate fossil record, including a large
assortment of fossil mammals. There is a wide band of Quaternary deposits along the modern Gulf Coast and in several places in
west Texas. Fossils found in these deposits include bones of bison, mammoths, and mastodons.
At The Lake Worth Dam: There are two areas of focus at the Dam. Area “A” is located on steep incline area that can be
treacherous, so caution is advised. Remember, it is MUCH easier going down than going back up! It is an area where seasonal
rainfall has formed a gully which has eroded deeply into the strata of this region. You will be picking through this area, studying
the various strata, and looking for fossils of many types. Some of the more common fossils found in this area include: (clockwise)
AMMONITES, ECHINOIDS (sand dollars), and OYSTERS (aka Devil’s Toenails), and GASTROPODS. You will find many fossils if
you know what to look for:
In this area, you will also be going all
the way down the hill to the dam,
where you will find many large rocks
composed of nothing but fossil oysters.
This is an ancient oyster bed, that lived
in the shallow sea that was covering
this area during the Cretaceous Period,
from the Mesozoic Era.
Area B is far less treacherous, but still challenging
in many ways, and yields many fossils as well. You will
find ammonites, echinoids, oysters, and gastropods
here as well. Some of the terrain can be steep, so be
careful!
Your goal: Collect two fossils that you can carry back to class in a baggie!
In your journals, create a data table similar to the one below that can contain your fossil information
for the two that you collect while you’re on this fieldtrip. Please note…this data table should take an
ENTIRE page in your journal, so this example is not to scale. You will NOT have your journals in the
field, so it is important to know what data you are looking for. Make sure you read the table, and take
pictures in the field, of the places where your fossils are found. The goal is for each student to find
and document 2 fossils (one from each site), If you are extremely adept at locating fossils, and one of
your teammates is not, you may donate fossil finds to them. Be prepared to take plenty of
photographic evidence of the regions, to help you answer your analysis questions.
Fossil A
Description of location
(Qualitative data about fossil
location) Photographic evidence
will earn extra points! Use your
phones, and email me the
photos!
Description of fossil
(Qualitative data about fossil)
Photographic evidence will earn
extra points! Use your phones,
and email me the photos!
Quantitative Data:
Dimensions of Fossil
L x W x H (cm)
Quantitative Data:
Mass of Fossil
Grams
Quantitative Data:
Density of Fossil in g/mL
Detailed Sketch of fossil
Classification of fossil
(Look in fossil guide, or online,
and find best likeness) Done
upon return to classroom
Time Period
(according to fossil guide book
or internet site) Done upon
return to classroom
Type of fossil
(Zoolith; Phytofossil;
ichnofossil…etc) Done upon
return to classroom
Type of fossilization
(How was this fossil likely
formed?) Done upon return to
classroom
Fossil B
Analysis Questions:
1. Judging from the qualitative data collected at the site where each fossil was found, describe the probable
landscape when each of your fossil organisms was alive.
2. Using the fossils you found, explain what other organisms may have been abundant in the area.
3. Tell about your favorite part, and least favorite part of the fossil expedition.
4. If you were to help me plan this expedition next year, what would you suggest to make the experience
even better?
Don’t forget your error analysis and reflection BEFORE you hand in your lab.