Below is a clickable reference to geologic eras so you can see where the Cretaceous Period falls along the geologic time line referenced on the map above.
Another map of Dallas County geology clickable by location + nice zoom
click to zoom
Uplifting of the area could have significantly affected how far down the bedrock is now if it is there in the flood plain.
The following link is provided here for ease of access and was originally provided by the Dallas Observer:
In this document you'll find a map of the original course of the river in the last century at the time the levees were being built and a photo that shows what's left of the original channel that runs along Stemmons Fwy, p16. For fun, you can view the channel from Google Earth. If you do, be sure and take a close look at both the Western and Eastern extremes of the channel - the Eastern one appears to handle a lot of runoff from short Northwest Dallas.
OK, just one more in case you don't have it: There's a Margaret Hunt Bridge webcam that can be found at the following URL:
