Geologic Time etc.

earth’s landscapes have been fashioned by great catastrophes

physical, chemical, and biological laws that operate today have also operated in the past

in an undeformed sequence of sedimentary rocks, each bed is older than the one above and youndger than the one below

layers of sedimentare generally deposited in a horizontal position

sedimentary beds originate as continueous layers that extednin all directions until they eventually grade out into a different type of sediment or until they thin out at the edge of the basin of deposition

geologic features that cut across rocsk must have formed after the rocks they cut through

rock mass adjacent tot eh one containing tjhe inclusions must have been there first in order to provide the rock fragments

the pieces that do not melt in the magma and remain lodged in; they remain as inclusions

when mineral-rich groundwater permeates porous tissues usch as bone or wood, minerals precipitate and fill pores and empty spaces; petritifed wood; often from a volcanic source

when a shell or another strucutre is burried in sediment and dissolved by undergound water

if the hollow spaces of molds are filled with mineral matter, casts are created

fine sedimenta encases the reamins of an organism. [ressire squeezes out the liquid and gaseous components and leaves behind a thin residue of carbon; effective at preserving leaves and delicate animal forms

if the film of carbon from carbonization is lost from a fossil preserved in fine-grained sediment, a replica of the surface, called an impressionm, may still show considerable detail

delicate organisms are preserved in the hardened resin of ancient trees (amber)

animal footprints made in soft sediment that turned into sedimentary rock

tubes in sediment, wood, or rock made by an animal. May later be filled with mnieral matter and preserved; spome of the oldest-known fossils are believed to be worm burrows

tracks and burrows, corpolites, and gastroliths

fossil dung

polished stomach stones that were used in the grinding food by some dinosaurs

rocks of similar age in different regions are matched up

when fossils are arranged accroding ot their age, they do not present a random or haphazard picture

wisepsread geologically

a group of fossil sused to establisht he age of a bed