Where your water goes

Rain that falls on Baltimore ends up in the Atlantic Ocean

1. Your sub-basin

   Upper Chesapeake

2. then

   Atlantic Ocean Seaboard

3. It arrives here

   Atlantic Ocean

Everything that falls here works its way east and north to the Atlantic. It is the drainage that carried the fur trade inland and the log drives back out, and the one Atlantic salmon and American eel still use — the eel travelling the whole length of it to spawn in the Sargasso Sea.

Basin 020600 (USGS hydrologic unit)

Under your feet

Baltimore sits on river deposits

About 3 million years old — from the ice ages and since — the most recent chapter.

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

1. At the surface3 million years oldNeither way

   River deposits

   Lowland Deposits · Pleistocene

   What it is

   Alluvium: loose sediment laid down by moving water on a floodplain, a delta or a bar. Some of it is decades old rather than millions of years.

   How it wears

   It is already weathered; that is what it is. The river sorts it, moves it, and puts it down somewhere else.

   What it means above ground

   The deepest, most fertile and most level soil in any landscape, which is why floodplains are farmed and towns get built on them. Also the ground that floods, and the ground that liquefies in an earthquake.

2. Below, layer 2101 million years oldNeither way

   Sedimentary rock

   Late Cretaceous sedimentary · Late Cretaceous

   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.