by Geyer, Alan R.
Environmental geology report ;
Roadside geology of Pennsylvania
Pennsylvania caves and other rocky roadside wonders
The practical geologist
Earth :inside and out
Reading the rocks : the autobiography of the earth
The geology of Centre County
Scenic science of the national parks : an explorer's guide to wildlife, geology, and botany
Hiking America's geology
Mineral collecting in Pennsylvania
Geology and mineral resources of the Bellefonte quadrangle, Pennsylvania
The history of earth : an illustrated chronicle of our planet
Basin and range
Rock formations and unusual geologic structures :exploring the earth's surface
Earth : an intimate history
Measuring eternity : the search for the beginning of time
Earth story : the shaping of our world
A collection of occasional surveys of iron, coal and oil districts in the United States, made during the last ten years
Rising from the plains
Backroads of Pennsylvania : your guide to Pennsylvania's most scenic backroad adventures
Pennsylvania's scenic Route 6 : a guide to historic sites, towns and natural lands
In suspect terrain
Dirtmeister's nitty gritty planet Earth : all about rocks, minerals, fossils, earthquakes, volcanoes, and even dirt!
Geology the study of rocks
Discovery Channel rocks & minerals : an explore your world handbook
Nature's extremes : inside the great natural disasters that shape life on earth
One strange rock
An introduction to fossils and minerals : seeking clues to the earth's past
Inside the earth
Annals of the former world
Guide to the state historical markers of Pennsylvania
Nature's clocks : how scientists measure the age of almost everything
The magic school bus : inside the Earth
The universe within : discovering the common history of rocks, planets, and people
Chesapeake invader :discovering America's giant meteorite crater
Rocks & minerals
My teacher is a dinosaur : and other prehistoric poems, jokes, riddles, & amazing facts
Explore rocks and minerals!
Pennsylvania. Bureau of Topographic and Geologic Survey.
Bolles, William H.
> Pictorial works.