1. Las Positas College
  2. Geology Program
  3. Display case 2420

Geology Program

Display case outside 2420

The skull in the display case is 1/10 size. Actual size of a real skull of this animal features 6 inch teeth and is 4 1/2 feet from back of skull to front of jaw. It is a Tyrannosaurus Rex, T. Rex for short.

  1. Whelks are carniverous marine gastropods that can drill through the shells of potential prey. The live in the midlittoral zone along side barnacles and anemones. There is also an abalone shell on this table.
  2. Chambered nautilus are cephalopods like the octopus and cuttlefish. They are related to an ancient group of species, the ammonites( see below #7). Chambered nautilus detect food by smelling the ocean currents.
  3. Gypsum is a common mineral, chemical formula CaSO4; Calcium Sulfate. The sheetrock in your house is made of gypsum because it is light, strong, and won't burn.Gypsum is mined in California in several desert locations. Gypsum is also used to correct soil pH and improve soil texture for crops.
  4. Halite is common table salt. Halite is composed of sodium and chlorine atoms arranged in a molecular structure that forms natural cubes. Because halite is a lighter than average mineral, it tends to move upward in rock formations, creating 'salt domes'. Halite is often mined at the seashore by creating salt retention ponds.
  5. Quartz is a hard, glassy mineral, common in many rocks including granite. Quartz is used in industry for guages, heat lamps, prisms and lenses. Some forms such as amethyst and tiger eye are commonly used in jewelry. Quartz is estimated to comprise 12% of the Earth's crust.
  6. Brachiopods are a marine bivalve that are also called lampshells.They wre the most abundant and diverse invertebrates of the Paleozoic.They have had a wide variety of shell shapes over the eons, and continue to live today, even though most people have never heard of them. They are truly a living fossil.
  7. Ammonites are the earliest cephalopods, first found in the Cambrian. They ranged in size from less than an inch across to over 4 feet across. They swam much like a chambered nautilus does today. There have been hundreds of different ammonite species, sadly all are extinct today.
  8. Trilobites lived only in the Paleozoic. They were marine creatures that lived on the sea floor, similar to the horse shoe crab of today. They had a hard carapace similar to the horse shoe crab of today. They burrowed in the soft sediments seeking anything small and edible.They molted, shedding their shells as they grew, which probably helped give them such a large representation in the fossil record; each animal might leave behind 20 shells.
  9. WHAT IS NUMBER 9? Email me your answer cedson@laspositascollege.edu Could be extra credit if you figure it out....Here are a few hints. These creatures live in colonies up to two feet across.Some of the species have been around for over 500 million years. They are still found in oceans today but are most common in tropical seas.
  10. Sharks are a great design- they have been successfully cruising the oceans for over 420 million years. The greatest threat to living shark species is over- fishing. Sharks mature late and reproduce on a small scale, plus their world wide numbers are not known. Megalodon is an extinct shark species that was the largest known. Teeth of shark species through geologic time have varied from tiny to almost 6 inches long. Megalodon was over 60 feet long!
  11. Sand dollars are frisbee shaped shells that are purple while the animal is alive. Sand dollars eat detritus in the soft marine sediments in the lower tidal zone. They are closely related to the spiny sea urchin, and move slowly across the sand the same way.
  12. Sea scorpions are an extinct species of aquatic creatures that lived in both fresh and salt water. They resembled land scorpions in some ways, but the largest marine varieties were over 7 feet long! These were among the largest marine predators during the Ordovician and Devonian time periods.Called Eurypterids, these animals died out in the Permian extinction.
  13. Geodes are also called 'Thunder Eggs'. They are spherical rock formations that are sedimentary in origin. Most have layers of quartz or calcite crystals in their hollow centers, forming a beautiful inner sphere. One must break or cut them in half to find out what is inside.
  14. Phyllite is a slaty metamorphic rock with sheen. It is commonly found in places like the Appalachian mountians. If you smash mudstone into slate and continue to smash it, the grains will become more aligned and the sheen characteristic will develop. If the rock is flattened even more it may progress to schist, where the sheen becomes actual spangles or sparkles of mica grains.
  15. Glossopteris is an extinct plant group, with 'tongue shaped' leaves, hence the name. It was common in the Permian, and died out completely in the Permian Extinction.
  16. Horn coral are an extinct group that ranged from a centimeter to a meter in length! They were solitary not colonial in most cases.
  17. Sandstone is a common California rock, made of sand particles glued together by chemical cement like calcite or quartz, and compaction. Cliffs in California made of sandstone are often very soft and suffer lots of landslides and mass wasting during winter storms. Sandstone can be banded in color like this sample, and be called Rainbow sandstone.
  18. Fuchite mica is a sparkly green form of mica. It looks 'fake' to many students but is in fact a naturally occuring mineral. This form of mica is very soft, and can be scratched with your fingernail.
  19. Pumice is volcanic foam; it actually floats in water. Near Crater Lake is a huge area covered in Pumice called the Pumice Plain. Pumice can come in a number of colors; red, grey, tan, cream and brown.
  20. Pyrite is iron sulfide and is commonly called Fool's gold. It is harder than gold, and has a grey streak. Pyrite forms in metamorphic processes where pressure is changing mudstone into slate.
  21. This granite stream cobble is an example of spheroidal weathering and abrasion. Its rounded shape is due to saltation in the stream bed, gradually wearing away all the corners. The eroded corners become the light colored sand so common on California beaches.

For more details on specific varieties email me (see above)

geology display case 1

geology display case 2

geology display case 3

geology display 4

geology display case 5

geology display case 6

geology display case 7

For more information please contact:

Ruth Hanna
Geology Faculty
Office 1829 / 1824
(925) 424-1319
rhanna@laspositascollege.edu

Carol Edson
Geology Lab Technician
Room 1824
(925) 424-1336
cedson@laspositascollege.edu