Across
- 3. the largest division of geologic time
- 4. The geologic law/principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it.
- 8. any method of determining whether an event or object is older or younger than other events or objects
- 10. Hardened tree sap, yellow to brown in color, often a source of insect fossils
- 12. the largest physiographic province in Virginia; between the Fall line and the mountains of the Blue Ridge
- 15. any method of measuring the age of an event or object in years using radioactive isotopes
- 16. Virginia province which lies to the West of the Valley and Ridge; source of Virginia's most valuable mineral resource
- 18. A trace of an ancient organism that has been preserved in rock.
- 20. An igneous rock layer formed when magma hardens beneath Earth's surface
- 21. A fossil created by an impression.
- 24. long parallel ridges to the west of the Blue Ridge mountains which are part of the major landform feature of North America; a region of karst topography
- 25. fossils of widely distributed organisms that lived during only one short period
- 28. The impression of an organism in a rock (hollow)
- 29. "Law of..." in a sequence of sedimentary rocks, layers of rock were originally formed lying horizontally
- 30. Age of reptiles
- 31. Any piece of rock (clast) has become incorporated into another rock, this clast must be older than rock matrix it is included in it
- 32. the tallest mountains in Virginia; folded and faulted igneous rock formed when African and North America collided
- 33. the time it takes 50% of radioactive isotopes to decay to stable
Down
- 1. era that began about 66 million years ago, known as the "Age of Mammals"
- 2. A description of plants or animals that have been preserved by being "turned to stone"
- 5. the division between the Piedmont and the Coastal Plain, where various rivers cross from hard bedrock to soft sediments; marked by a line of rapids and waterfalls
- 6. A trail, nest, burrow, or evidence of organism found fossilization in sediments; it shows the activity of an organism, but is not made of the organism itself.
- 7. "Law of..." An inclusion must be older than the rock it is enclosed in
- 9. a crack in the earth's crust resulting from the displacement of one side with respect to the other
- 11. the youngest province in Virginia; from the Fall Line eastward to the Atlantic Ocean; a broad, flat area of unconsolidated sediments along the coastline
- 13. Virginia's most valuable mineral resource
- 14. the part of geologic time 570-245 million years ago ; invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees were dominant
- 17. a fossil copy of an organism in a rock (filled)
- 19. formed when layers of sediment such as clay, mud, silt, or sand hardened over million years. These types of sediments are laid down in lakes, swamps and oceans.
- 22. A scientist who studies the forms of life that existed in former geologic periods, mainly by studying fossils.
- 23. A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time
- 26. no longer in existence
- 27. makes up about 88 % of earth's history; when the oceans, atmosphere, and continents were formed