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(plural cast fossils) A fossil formed when an animal, plant, or other organism dies, its flesh decays and bones deteriorate due to chemical reactions; minerals gradually enter into the cavity, resulting in a cast, also called a mold fossil, which is in the general form of the original organism. Link/Cite. Fossil - Types. 1 Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages). They work on the premise that, although different sediments may look different depending on the conditions under which they were deposited, they may include the remains of the same species of fossil. The mold is the impression in the rock it left. This is like pouring chocolate into a mold. When the chocolate hardens, it pops out as a chocolate cast, ready to eat. Examples: Fossil shells are often casts, and shell impressions on rock are often molds. A fossilized footprint is a mold. Plant fossils and trilobites are often found as casts and molds. There are two main types of fossils: body and trace fossils. 1 Body fossils - Body fossils are fossils where some portion of the actual organism's body remains as part of the fossil. This might be a tooth or piece of bone. 3. What is a cast fossil? 4. What is a true form fossil? Motivation: Ask students if they know what the different types of fossils are. Can they describe different kinds of fossils? Show the following types of fossils, taken from http://enchantedlearning.com/subjects/dinosaurs/dinofossils/Fossiltypes.html and discuss each one. The first picture is a fossil in amber, the second one is a trace fossil, the third is a mold fossil, and the last one is a cast fossil. Procedure: Write on the bottom of each fossil their name and if it is a cast or mold. Have students form two lists to describe what they see in the two 'fossils', hair, shape, texture, size, color, etc. Have students write on paper which fossil gives them the most information, mold or cast (3-D) and why. Cast and mold are a type of fossilization where the physical characteristics of organisms are impressed onto rocks, especially coarse porous rocks such as sandstones. Fossils are remains of life from the past. The most common kinds of fossil preservation are molds and casts. The activity will give students the chance to make modern day molds and casts. Goal: To teach students two common fossil types; a mold and a cast. Best Answer: C. A mold fossil is filled with water that contains minerals that harden into a stone replica. A is how you make a trace fossil B is how you make a ... There are four primary types of fossils: mold fossils, cast fossils, trace fossils and true form fossils. Cast fossils are formed when the imprints created by fossils, called mold fossils, are filled in by minerals over time. Definition of Cast Fossils. A cast fossil is a type of fossil indicator. Query: how is a cast fossil formed?
Output:
Cast fossils are formed when the imprints created by fossils, called mold fossils, are filled in by minerals over time.