It All Starts with the Geology!

Since we are facing a REALLY cold week here in central Ohio, I thought I'd provide a diversion with a post about a recent trip to the Florida Keys. Today, the Keys are accessed via U.S. Highway 1, which stretches 127.5 miles from Key Largo to Key West. The route is flanked by a hodge-podge of roadside retail establishments, making for dismal scenery, except at the bridges where views of clear turquoise-blue water and small forested islands are spectacular. A good way to avoid the commercial overload is to visit the state parks, which have done their best to preserve a bit of the "real Florida". 

To understand both the natural and human history of the Keys, some background is necessary. The rock that underlays this archipelago was formed over 125,000 years ago by tiny marine corals that laid down layer upon layer of what became "Key Largo Limestone". Changing sea levels exposed the islands that we see today. The alkaline pH and porosity of this rock has influenced the types of vegetation on the islands, which in turn has influenced island wildlife. The rock has also had a huge impact on the human history of the Keys.

Various tribes of Native Americans inhabited the Keys before European explorers arrived. Gradually non-natives settled the land with small homesteads and farms. Then in 1905 along came Henry Flagler, one of the wealthiest men in the world, who had the idea to build a railroad from Miami to Key West, to bring tourists to the area and to develop Key West's deepwater port to support trade from the Panama Canal. Many years were required to complete the railway, due to the huge engineering challenge, the heat, mosquitoes and hurricanes. 

Vast amounts of limestone comprising the Keys made construction of the railroad possible. Thousands of tons of fill were taken from area quarries for the roadbed and bridge approaches. Windley Key Fossil Reef Geological State Park protects and interprets one of these quarries. Here is a view of the quarry walls and some of the equipment used to cut and move the stone:

A closer look at the walls of the quarry reveals fossilized specimens of ancient coral animals:

A bit of polishing produces attractive building exteriors:

The abundance of shallow limestone means that soils on the Keys are extremely thin. Despite this, lush and diverse vegetation covers the undisturbed areas, particularly in the "hammock" forests:

On the left is a poisonwood tree, which is related to poison ivy and is said to cause
worse dermatitis. I love the mottled bark but restrained myself from touching it! On
the right is gumbo-limbo, a common tree in south Florida which has characteristic
reddish, peeling bark. Over 40 different tree species occur in small Windley Key State Park.

Some interesting flowers can be found in the Keys, including this monk orchid. This plant originated in west Africa, and botanists theorize that its tiny seeds were transported on the wind to South America in the 1800s. It has since spread northward, and is now found as far north as central Florida.

Stately coconut palms and shrubby sea grape often dominate the shorelines of the Keys:

Butterflies aren't abundant on these small islands in the winter, but a few gems can be found. In a small citrus grove in John Pennekamp Coral Reef State Park we found a tiny silver-bordered hairstreak:

and a fulvous hairstreak:

We had looked long and hard for a hammock skipper and finally found one on our latest visit to the Keys:

Another butterfly that doesn't stray too far from warm shores is the mangrove skipper:

And the lovely martial scrub-hairstreak rarely strays from bay cedar, its caterpillar host plant:

Although relatively common, we always enjoy seeing a gulf fritillary:

Today, suitable habitat on the Keys for these creatures and many others is mainly restricted to parks and preserves. Habitat loss has been extensive, rendering once-common wildlife rare or extirpated. Henry Flagler's dream of opening the Keys to tourists and commerce succeeded, but natural areas have been vastly reduced as a result. 

The railroad was completed and finally, in 1912, the first train arrived in Key West. The dream didn't last long, though--hurricane winds of 200 mph swept through the Keys on Labor Day, 1935, and despite the tons of underlying limestone fill, 40 miles of track were destroyed. Rebuilding was impractical due to the depression, but eventually US Highway 1 was completed. Here is a piece of what remains of Henry Flagler's project at beautiful Bahia Honda State Park--Highway 1 is visible on the far right: