INTRODUCTION Scientists have good evidence that the earth is very old, approximately four and one-half billion years old.Scientific measurements such as radiometric dating use the natural radioactivity of certain elements found in rocks to help determine their age.Sequencing the rock layers will show students how paleontologists use fossils to give relative dates to rock strata.
Materials: two sets of sequence cards in random order (set A: nonsense syllables; set B: sketches of fossils), pencil, paper Procedure Set A: 1) Spread the cards with the nonsense syllables on the table and determine the correct sequence of the eight cards by comparing letters that are common to individual cards and, therefore, overlap.The first card in the sequence has "Card 1, Set A" in the lower left-hand corner and represents the bottom of the sequence.If the letters "T" and "C" represent fossils in the oldest rock layer, they are the oldest fossils, or the first fossils formed in the past for this sequence of rock layers. Now, look for a card that has either a "T" or "C" written on it.Since this card has a common letter with the first card, it must go on top of the "TC" card.For example, most limestones represent marine environments, whereas, sandstones with ripple marks might indicate a shoreline habitat or a riverbed.
Return to top The study and comparison of exposed rock layers or strata in various parts of the earth led scientists in the early 19th century to propose that the rock layers could be correlated from place to place.
This would also mean that fossils found in the deepest layer of rocks in an area would represent the oldest forms of life in that particular rock formation.
In reading earth history, these layers would be "read" from bottom to top or oldest to most recent.
PALEONTOLOGY, AND in particular the study of dinosaurs, is an exciting topic to people of all ages.
Although most attention in today's world focuses on dinosaurs and why they became extinct, the world of paleontology includes many other interesting organisms which tell us about Earth's past history.
In this activity, students begin a sequencing activity with familiar items letters written on cards.