Question: How to tell which rock units are older … or younger … than other rock units?




·      Earth is dynamic LINK


·      The present is the key to the past; the past is the key to the present. Lots of keys! LINK


·      Geologic time is deep time . LINK


·      Utah hasn’t always been “here” LINK


·      Utah’s three physiographic provinces differ… because they have had different geologic histories LINK LINK

Utah’s Basin and Range physiographic province LINK Link to Hamblin -p 228 and 229 Tule Valley

Utah’s Rocky Mountain physiographic province LINK Link to Hamblin - p 213 High Uintas Kings Peak

Utah’s Colorado Plateau physiographic province LINK Link to Hamblin - p115 Monument Valley

And ties to human geography LINK - IHC facilities of 1990s


·      Older versus Younger … generalizations LINK

Old bedrock, Young landforms LINK

Older underneath Younger (superposition) LINK

Datable materials LINK

Tilted younger than what tilted LINK

What cuts is younger than what is cut (cross-cutting relationship) LINK

Surfaces... lots of them! Distinguish cross-cutting surfaces from others (such as between layers of rock).

Cross-cutting surfaces to appreciate for Analysis of Utah Landforms.

(a) MOST PERVASIVE and MOST OBVIOUS and MOST easy to be oblivious to... EROSIONAL SURFACES.

LINK to image of UofU and Wasatch Front

LINK to image of cross section of Basin and Range

LINK to image of Monument Valley, to Kings Peak, to Tule Valley.


(b) fault... surface across which movement happens between large (really large) crustal masses.

(c) contacts... between LAYERED rock units -- conformable if no time lost across the surface; unconformable if a time gap such as the gap between units tilted by tectonics and those deposited across them.. And contacts between intrusive rock units such as granite magma that intruded and then crystallized as huge mass(es) into the bedrock now found in Little Cottonwood Canyon; or salt that intrudes the bedrock that underlies Moab, UT.




SALT LAKE COUNTY… nine geologic chapters . IN COLOR. GO BY LABELS


BINGHAM COPPER MINE… what it took to have our world class copper ore. LINK