Where your water goes

Rain that falls on Oklahoma City ends up in the Gulf of Mexico

1. Your sub-basin

   Lower North Canadian

2. then

   Arkansas River

3. then

   Mississippi River system

4. It arrives here

   Gulf of Mexico

This water joins the largest drainage in North America and travels south for thousands of kilometres to the Gulf. What runs off the fields upstream of you arrives there too, which is why a dead zone the size of a small country forms off Louisiana each summer.

Basin 111003 (USGS hydrologic unit)

Under your feet

Oklahoma City sits on sandstone

About 299 million years old — from the age of the first forests, amphibians and reptiles.

All the kinds of rock, and how each one forms →

1. At the surface299 million years oldSours the soil

   Sandstone

   Salt Plains Formation · Permian

   What it is

   Sand grains, mostly quartz, stuck together by a natural cement of silica, calcite or iron oxide. Rub a weathered face and grains come off on your hand.

   How it wears

   Crumbles back into sand along its bedding, and leaves overhangs and shelters where a soft layer sits beneath a hard one. Iron-cemented sandstone weathers to rust red.

   What it means above ground

   Sandy, quick-draining, usually acid soil. Sandstone is porous, so it stores groundwater and releases it steadily — sandstone country has reliable springs where the water table meets the hillside.

2. Below, layer 2541 million years oldNeither way

   Sedimentary rock

   Paleozoic sedimentary rocks · Paleozoic

   What it is

   The family that covers about three quarters of the land surface, in a thin skin over everything else. Some geological maps say only this much, which still tells you it will be layered and may hold fossils.