Topographic maps

• V leads upstream

• Vertical exaggeration = horizontal scale/vertical scale

• As the crow flies → straight line

• Relief = highest point - lowest point

Geologic maps 

• Contact → location on the surface where two rock layers touch

• Original horizontality → rock layers are deposited horizontally

• Superposition → oldest layers on bottom, and they get younger as you go up

• Uncomformity → old erosional surface, gap in geologic history = erosion period

  • Disconformity → uncomformity between parallel layers 

  • Angular uncomformity → horizontal parallel sedimentary layers are deposited on tilted and eroded layer → this make an angular fiscordance with overlying layer

• Cross cutting relationship → geologic feature (igneous intrusions, faults, etc…) younger than rock layers and features they cut across

• Transgression → fining upward sequence, rise in sea level

• Regression → coarsening upward, drop in sea level

• Sandstone → largest particles

• Shale → medium size particles

• Limestone → smallest particles

Time

• Precambrian → 4.5 mya

• Paleozoic → 543 mya - 290 mya

• Mesozoic triassic → 248 mya

• Mesozoic jurassic → 206 mya

• Mesozoic cretaceous → 144 mya - 65 mya

• Cenozoic Tertiary → 65 mya - 5.3

• Cenozoic quaternary → 1.8 - now

Central texas geobiology

• Paleozoic (545-245 mya)→ ocean, mountain building, deposition dominant

• Mesozoic (245-65 mya) → spreading of continents, animals on land, ocean, air, deposition dominant

• Cenozoic (65-present) → ocean receded, erosion dominant, differential loading and faulting

• Rivers/streams

• Point bars → terrace formations deposited on inside of stream bend

• Terrace formation

• Volcanic ash layering