White Rock Lake in Dallas Was Once an Ancient Sea

Did you know that White Rock Lake in Dallas, Texas was once an ancient sea?     

North America was literally divided into two landmasses by a large inland sea called the Western Interior Seaway (also called the Cretaceous Seaway and the North American Inland Sea) that existed during the Mid-to-Late Cretaceous Period.

 Western Interior Seaway - 100 million years ago

This ancient, shallow sea had abundant marine life and stretched from the Gulf of Mexico in the south and through the middle of what we now know as the United States and Canada, meeting with the Arctic Ocean to the north. This sea was 600 miles wide and over 2,000 miles long. All of Texas would have been covered by this ancient sea.

The Cretaceous period succeeded the Jurassic Period approximately 144 million years ago and lasted to approximately 65 million years ago. The word Cretaceous comes from the word for "chalk," a soft, white, porous sedimentary rock that is a form of limestone. Indeed, if you walk around White Rock Lake, you will see intermittent outcrops of white limestone, and this is how the lake got its name: White Rock Lake.

If you look carefully at these limestone outcrops, you may be lucky enough to identify crustacean shells dating back to the Cretaceous Period, such as these found at Winfrey Point.

 Shells and other items found in the limestone at Winfrey Point

The sea began to wane about 70 million years ago and the ancient sea bed gradually became exposed over time through erosion and other upheavals. This ancient sea bed is the white rock that we now see exposed around the lake, especially the area below the spillway where large tracts of limestone are clearly visible, and known locally as Austin stone.

It is during the Cretaceous Period that we find the first fossils of many insect groups, modern mammal and bird groups, and the first flowering plants (called angiosperms). Around White Rock Lake, the most common fossils to be found are organisms such as clams and oysters. Shark teeth, fish and marine reptile remains have also been found at the lake on rare occasions.

 A closer view of the shells

At the end of the Cretaceous Period, 65 million years ago, an asteroid hit Earth in the Yucatan Peninsula, Mexico. This event resulted is what we now call the Chicxulub impact crater, buried under the Yucatan Peninsula. The crater is more than 110 miles in diameter.

It has been estimated that half of the world's species went extinct at about this time (including the Dinasaurs), either from the impact of the asteroid or other reasons, such as environmental changes. Whatever the cause of this extinction, this asteroid event marks the end of the Cretaceous Period.

The next time you take a walk around White Rock Lake, keep your eyes peeled. That stone you are kicking may just turn out to be a 60 million-year-old fossil.

Birds in flight: The Ring-billed Gulls of White Rock Lake

If you visited White Rock Lake, Dallas in winter, you will no doubt have witnessed the raucous behavior of the ring-billed gulls (Larus delawarensis) in and around Sunset Bay. These noisy, opportunistic birds make their presence known and are often seen taking food from less fortunate waterfowl.

All of the "birds in flight" images below were taken at Sunset Bay, White Rock Lake. 

A soaring ring-billed gull on the lookout for some food

If you visit White Rock Lake now you will notice that Sunset Bay is a lot quieter. The gulls have gone. Ring-billed gulls are migratory and some of them spend their winters at White Rock Lake in east Dallas, Texas.

 Ring-billed gulls migrate and spend the winter at White Rock Lake

Ring-billed gulls are easily identified from the black ring near the tip of its yellow, short bill, as well as its white head and gray wings. Its legs and feet are yellow. The eyes are yellow with red rims.

 Ring-billed gulls they were hunted for their plumage

 

Ring-billed gulls breed near lakes, rivers or the coast in Canada and the northern United States.

Larus delawarensis in flight over Sunset Bay

The gulls are pretty birds and in the late 19th century, they were hunted for their plumage.

Ring-billed gulls flying across Sunset Bay

Ring-billed gulls nest from mid-May through June and they return to their nesting site well before it is time to nest in order to establish its territory.

The black ring at the tip of the gull's beak is clearly visible

Ring-billed gulls takes three years to reach its breeding plumage.

Ring-billed gulls foraging for food at Sunset Bay

Texas is known for its clear, blue skies in winter.

The gulls nest from mid-May through June

Although the gulls often visit Sunset Bay to forage for food, they love to spend a lot of their day sitting in the shallow water below the spillway, waiting for morsels that have washed over the spillway wall.

Ring-billed gulls in flight

Ring-billed gulls nest from mid-May through June and they return to their nesting site well before it is time to nest in order to establish its territory.

And that’s why Sunset Bay is a lot quieter this time of year.

The Beautiful Buttonbush Begin to Bloom at White Rock Lake

The Buttonbush (Cephalanthus occidentalis) have started flowering at White Rock Lake in east Dallas. And what a spectacular sight it is! These perfect, beautiful Buttonbush flowers are clustered in white "balls," about the size of a ping-pong ball, and resemble a pincushion.

A Buttonbush cluster of stunning white flowers

Cephalanthus occidentalis is part of the coffee family, Rubiaceae, and is native to eastern and southern North America. The common names for this plant include Buttonbush, Common Buttonbush, Button-willow and Honey-bells (probably because of their fragrance).

Bees and butterflies visit the Buttonbush flowers for nectar, and they assist the plant with pollination. 

 Bees and butterflies visit the Buttonbush flowers for nectar

The Buttonbush is a semi-aquatic shrub that grows in water or moist soil. The plants in the images below were growing along the bank of the lake. Because of their love of water, Buttonbush plants are often seen in marsh areas, and bordering streams, ponds, and lakes. 

Crab spiders (see image below) blend in well with the white Buttonbush flowers, and the spiders love laying in wait for an unsuspecting insect to drop by. 

 Crab spider waiting for the insect to get closer

They also grow in w

Buttonbush blooms from June to August. In the image below, the flowers have begun to die off. When the flowers disappear, they leave brown, ball-like fruits filled with seeds. The seeds are eaten by ducks (especially loved by Mallards), geese, and shorebirds, so the waterfowl of White Rock Lake are in for a treat. The fruits stay on the plant from September to October.

 When the Buttonbush flowers die, seed balls will form

Giant Spider Webs at White Rock Lake, Dallas

There are several giant spider webs around White Rock Lake that envelop portions of trees and shrubs. Presumably, these webs are the combined work of many spiders. The images below were taken along the banks of the lake. 

Whilst these spider webs are unsightly, they are nowhere near as big as the phenomenon that made world-wide news in the summer of 2007 when Lake Tawakoni State Park, about 50 miles east of Dallas, had huge trees completely enveloped in spider webs.

Giant spider webs envelop portions of trees at White Rock Lake

The giant spider webs of Lake Tawakoni were apparently the work of the Guatemalan long-jawed spider (Tetragantha guatemalensis ) that is found from Canada to Panama, and even the islands of the Caribbean. These spiders do their work at dawn and dusk.

In the image above and below, the web is so thick that it presumably prevents sunlight from getting to the leaves for photosynthesis which is why the leaves are dying.

The webs prevent sunlight from getting to the leaves of the plants

The dead leaves below are no longer covered by a spider web. The web may have been washed off by the heavy rains that we had in the past twenty-four hours, or the spiders may have removed the web. Sometimes spiders tear down their web in the morning (although it is unlikely in this case). They roll up the silk into a ball and eat it. The web provides protein for the next time the spiders have to make a web.

The leaves quickly die off when covered by the spider webs

Let’s hope this phenomenon does not escalate to the extent that it did at Lake Tawakoni.