We know a lot of the details about our house and it’s little spot on the Earth.  Here’s a quick summary:

• 2007 - we purchased the house from the estate of Henrieta Walker.
• 1961 - the house was purchased by Mr. and Mrs. Walker.
• 1959 - 1961 - two different owners occupy the house for about one year each.
• 1911 - 1959 - the house is occupied by its original owner, Garner Whiteman, who was a Chemist working for the Department of Agriculture.
• 1911 - The house was built by the developer Harry Wardman as part of a large group of row homes built between 1910 and 1914, and bounded by Spring, 14th, Monroe and Holmead Streets.
• c 1800 - 1910 - The area was a farm, eventually sold by Mr. Holmead to Harry Wardman.

But what about all the time before that?  Forests, Native Americans, Dinosaurs?  I have been thinking about this because I  just finished digging a pit in our back yard nine feet long by three feet wide by three feet deep.  I wondered how long all of that dirt had been there as I cursed the rocks in my path.  There were very clear layers of sediment that I was passing through and we figured they must have been at least thousands of years old.  Here’s a little of what I’ve learned of the history of our back yard.

First, though, an important point about our location, just east of Rock Creek Park.  All the rock in Rock Creek Park is the remains of a giant mountain range.  What is now the Appalacian Mountains was once as big as the Alps, but over millions of years it has eroded to what is there now.  At the eastern edge of this range sits Rock Creek, and the high ridge that the creek follows is the remnaints of the eastern edge of that mountain range.  This is important to our back yard because this mountain range was a natural barrier to the ocean which, at many time in the past, covered our back yard.

In periods where the Earth was cool, water was locked up in glaciers, ocean levels were lower, and our backyard was above sea level.  When the Earth warmed and the oceans rose, we were under water again, and a new layer of sediment was deposited on our backyard.  Every cycle of cool and warm created another layer of gunk for me to dig down into.

• 237 million years ago (mya) - It was a long drive to the beach for us, because we would have had to drive across North Africa to get to the ocean, about where Lybia is now.  Along the way our car may have been stepped on by Traissic period beasts, such as the Placerias.
• 200 mya - 14,000 years ago - North America broke off from Pangea and our backyard drifted northward from near the equator to its present location.  Now that Africa was not there to protect us from rising oceans, our backyard was continually flooded and dried out again, leaving deposits of silt, clay, and microscopic sea creatures.  Rocks from the mountains that are now Rock Creek Park were tumbled along the coast line, made smooth, and dropped in layers to get in my way millions of years later.
• 14,000 - 10,000 years ago - Humans made their first visit to our backyard some time during this period, coming from Asia across the Bering land bridge and quickly spreading throughout N and S America.  - did they hold our first barbeque?  I hope they had vegiburgers.
• 10,000 years ago - c 1650 - I don’t know much about what the Native Americans did in our backyard, if anything.  There were a lot of mosquitoes, even then.  Our backyard sits on fairly high ground overlooking the swamp that is now our nations’s capitol.
• c 1650 - c 1800 - ??? I need to do some more research, I guess.

Our backyard is part of what geologists refer to as the Atlantic Coastal Plane, which extends from NYC down to the Yukatan Pennisula, and from the Atlantic Ocean to the Appalacians, or in our case, to that high ridge line just west of Rock Creek.  In some places the sediment deposits are 13,000 feet deep, and I only had to dig three feet.  So I don’t know exactly how old that layer of gray crud is at the bottom of my pit, but each layer I could see correspods to one ice age.  Ice ages come along evey 15,000 years or so, and I saw many, many layers.