Friday, June 5, 2015
My newly rototilled garden in Cleveland Heights, Ohio!
During the last ice age, Lake Erie was about double its size. About 14,000 years ago, glaciers covered most of the Great Lakes except for the western two-thirds of Lake Erie. Along the southern border of this vast ice sheet was prehistoric Lake Maumee -- which covered the southern end of Lake Michigan, the western two-thirds of Lake Erie, and about 30 miles south of the glacial sheet in all directions. The lake extended even into western Pennsylvania, where it lapped against the the Appalachian Plateau -- the foothills of the Appalachian Mountains.
The ice sheet had already scoured all the topsoil from the area around Lake Erie. All that was left was incredibly thick sheets of granite. While it existed, Lake Maumee laid down a vast quantity of silt, which formed a thick layer clay at the bottom of the lake.
As the glacial ice sheet retreated, it found a soft spot in the granite sheet. The ice continued to scour away at this soft spot, carving out what we know today as the Cuyahoga River.
Abou 8,700 years ago, Lake Maumee finally drained away as the ice sheets swiftly retreated and the area dried out.
The city of Cleveland Heights is built atop the Portage Escarpment, a geological feature some 2 to 4 miles wide that connects the Appalachian Plateau in the east to the Erie Plain in the west. Early residents of Cleveland settled along The Flats, a low-lying floodplain on either side of the Cuyahoga River bounded by steep slopes that rose up to the Erie Plain.
Why tell you this? Because it explains why topsoil in Cleveland Heights is only about 12 inches deep, and rarely more than 18 inches deep.
Because it explains why topsoil in Cleveland Heights is full of clay. Organic matter than falls on top of the clay doesn't get mixed in very well with the sticky, gummy clay. It just sits on top, decomposing, and leaving the soil below not very good for plants.
Rain, too, just runs off the clay (or ponds on top). This tends to leach nutrients from the thin layer of composted topsoil, worsening the situation for plants.
If you're a Cleveland Heights homeowner, and you have grass, you'll need to aerate your lawn every year so that the compact clay is broken up and the grass can lay down deep roots. Otherwise, you grass just sits on top of the clay, and is easily damaged or torn up.
If you're a Cleveland Heights gardener, you need to rototill your garden down about 12 inches to break up the clay and aerate it. You also need to till mulch -- grass clippings, vegetable food leftovers, coffee grounds, wood chips, etc. -- into the soil so that the earth becomes good topsoil rather than an inch-deep woeful layer of topsoil sitting atop the clay.
So, I rototilled. :) Now the planting gets done! I just want pumpkins, some Indian corn, and maybe some flowers. Not much.