Over the Edge.....

Having just read the web diary entry for yesterday "Grimmest day in the wet and cold" I am feeling that Mark might well like to draw a veil over 18th January. However, the title of this posting has nothing to do with Mark's state of mind but is rather about a geographical divide... of which more later.

Yesterday Mark cycled the 130km from Blanco to Bastrop and hopefully, after a depressing day of rain, was able to look at 'the big picture' like the one below and be reassured by progress....

I reckon today has been better weather-wise. Certainly the radar view today suggests that all the rain of yesterday has moved away east.....
About 30kms after leaving Blanco yesterday Mark passed closed to the largest body of water which we have seen for some days. Given the weather, however, it is doubtful if he would have seen Canyon Lake! Canyon Lake is a reservoir on the Guadalupe river and when it was built in the early 1960s its main purpose was flood protection for communities lower down the Guadalupe river. By holding back the waters of the river, damaging floods could be lessened, and in the process, the water used for HEP production and domestic and agricultural water supply. It is therefore a multi-purpose water management scheme. The lake has become a very important recreation destination with marinas, camping grounds, holiday accommodation etc. lining its shores.

During a flood episode in 2005, the dam was unable to hold back enough water and the surplus poured over the spillway and in just three days carved out the Canyon Lake Gorge- a powerful testimony of the erosive capacity of water!

Beyond Canyon Lake, even through the driving rain, Mark would have been aware of a significant drop in altitude as he approached San Marcos. Thie is the 'edge' referred to earlier and visible below as a NE / SW trending line in the landscape when viewed from the air.

The town of San Marcos sits astride that line at the foot of the Balcones fault line. The surface expression of the fault is the Balcones Escarpment, which forms the eastern boundary of the Texas hill country and the western boundary of the Texas coastal plain . Many cities are located along this fault zone, and that is not a coincidence. Frequently, springs such as San Marcos Springs emerge at the foot of a fault providing a source of fresh water and an obvious place for human settlement. Below, San Marcos "on the edge".......

East of San Marcos there is a significant change in geology which you should be able to discern even in this low res image. The greens of the Texan hill country end at the Balcones fault and to the east of it the 'striped' area is a swathe of impermeable rocks on which water can be retained without difficulty at the surface......

On the subject of water, I spotted this river feature close to Mark's route yesterday. It comes with the title "What happens next?" If you have been following the blog (from memory, postings about the Ganges valley and the River Murray), you will know!

Bastrop provided a welcome respite from the rain for Mark at the end of the day yesterday . It is apparently 'the most historic small town in Texas'. Its history dates back to 1804 which is a long time in American terms! The image below from Wikipedia carries the description "historic buildings with quaint shops and restaurants line the main street in Bastrop"