Where your water goes

Rain that falls on Jacksonville ends up in the Atlantic Ocean

1. Your sub-basin

   St. Johns

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 030801 (USGS hydrologic unit)

Under your feet

Jacksonville sits on marl

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 oldSweetens the soil

   Marl

   Undifferentiated sediments · Pleistocene

   What it is

   A mixture of carbonate mud and clay, in roughly comparable amounts. Neither pure enough to be limestone nor clean enough to be shale.

   How it wears

   Softens and slumps, shedding a sticky calcareous clay that holds water well.

   What it means above ground

   Heavy, sweet, water-holding soil. Farmers dug marl pits for centuries and spread it on acid fields, which is where the practice of liming comes from.

2. Below, layer 266 million years oldNeither way

   Sedimentary rock

   Cenozoic sedimentary rocks · Cenozoic

   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.