Friday, March 23, 2012

Week Four: Archaeology and geology

My one and only arrowhead, likely between 2,000 and 4,000 years old.

So far, I’ve only found one arrowhead in my life. I was seven or eight years old, combing the white rocks and pebbles strewn across a sandbar along the Blanco River in the 1960s. My father and brother, Steven, were looking, too. We always loved to take the dirt trail from my Grandfather Smith’s house in Wimberley down to “the rapids” on the river, either (depending on the season) to get wet or just explore. That afternoon, when I spotted the tiny pink piece, I was so excited! A real arrowhead!

On the way back to Papa’s house, though, I dropped my treasure in the leafy debris on the ground and nearly lost it. But, much to my relief, I found it again. To this day, I’ve kept my prized arrowhead in a matchbox that my other grandfather, Dudley Dobie, picked up back in the '60s at the State Bank and Trust Co. Inside are two other arrowheads, both perfectly intact, that he gave me.

Week Four of our Master Naturalist training with the Highland Lakes chapter covered archaeology and geology of the Texas Hill Country. We covered a LOT of material!

Tours of the Nightengale Archaeological Center are offered second and fourth Saturdays each month from 2 to 5 p.m. (February through November). Admission is free; donations accepted. Call 830-598-5261 for more info.

 Our day began at the Nightengale Archaeological Center, a wooded 10-acre site on Lake LBJ near Kingsland. According to the website, the prehistoric site was “discovered in 1988 when looters were caught stealing artifacts from LCRA-owned land. LCRA soon determined this site to be a major archaeological discovery.” It’s named after the late Bruce Nightengale, an archaeologist with LCRA who largely developed the learning center and its first exhibits. Members of the Llano Uplift Archeological Society help operate the site and give public tours.

[Note: Our thick Texas Master Naturalist Statewide Curriculum notes that the two spellings for archaeology/archeology are both accepted as correct. Just so you know it's not me making typos!]

Charles Hixson (Pat Hatten seated behind him) stands near framed artifacts owned by John Boland.

Archaeologist Charles Hixson, who assesses and inventories artifacts on LCRA-owned lands, gave the morning’s major presentation. He was assisted by Pat Hatten with the LUAS. 

First, Hixson explained the Prehistoric period (when indigenous Native Americans lived before written records) and the Historic period (refers to Old World peoples and their descendants, who collectively left written records).

In Texas, one of our oldest archaeological sites from the Historic period (300 years ago to present) is the Noah Smithwick Mill, built in the 1850s east of Marble Falls. His memoirs, Recollections of Old Texas Days, were published by UT Press in 1983; his book is also posted online (free).

In the Hill Country, the Prehistoric period reaches some 3,500 to 14,000 years ago. At dig sites, archaeologists excavate by layer by layer. The deeper the artifacts, the further back in time they date. Then and now, Earth erodes and decomposes, erodes and decomposes. Man contributes as well. The layers build up. Make sense? (Thanks to these classes, I better understand now!)

Radio carbon dating assists researchers in pinpointing ages of artifacts. Though expensive ($600 or so for one test), carbon testing pieces of charcoal found at a hearth site enables scientists to date points found nearby, Hixson said.

As an aside, Hixson recommended Stone Artifacts of Texas Indians by Ellen Sue Turner. “It’s not a price guide,” he said.

“Some people ask us what their points are worth,” Hatten interjected. Chuckling, he added, “NEVER ask an archaeologist that question!”

Texas’ timeline began with the earliest Paleoindians, who were mostly hunters 9,000 to 12,000 years ago. Next came the Arachaic Period, 9,000 to 1,250 years ago when native peoples largely survived by gathering plants. During the Late Prehistoric Period (about 1,250 to 300 years ago), people switched to bows and arrows, and fired pottery in earthen ovens. 

Hixson went on to discuss kinds of archaeological sites, such as campsites, quarries, rock shelters and burial sites. He explained levels of investigations and what criteria determine a State Archaeological Site.

John Boland with the LUAS shared about his extensive artifact collection, which he began in 1957 in South Texas and has meticulously documented along the way. After our classroom lectures, we hiked the Burrets Archaeological Trail, marked with signage. We saw a replica campsite and lots of native vegetation.

More than 100,000 artifacts have been uncovered at the Kingsland Archaeological Site (its previous name and scientifically designated as 41BT215).
A worked piece of chert.
Heading down the trail.

A replica dwelling from the Historic Period.

Pat Hatten explains how archaeologists conduct an excavation.
A grinding stone.

Charles Bierlie (left) and Sean Jones had a wealth of knowledge to share!

From Kingsland, we loaded up in our cars and drove to Inks Lake State Park, where we ate our sack lunches on the covered, lakeside deck at the Park Store. Then in the Maintenance Building, we learned LOTS about geology from Master Naturalist Charles Bierlie and park ranger Sean Jones.

“I firmly believe that geology is a core science,” Jones began. “It’s a stepping stone to understanding our natural worlds. To me, geology is a physical science that explains the history, composition and processes of Earth’s land and water. It’s more than just ROCKS.”

This place we call Earth, Jones said, is some 4.6 billion years old. Man’s only been here 2 million years, a mere sliver on Earth’s timeline. Inks Lake State Park’s history reaches back 1.3 billion years, Jones said. (Prehistoric people inhabited the area about 8,000 years ago.)

What is a rock? “I get a lot of stupid looks from people when I ask that,” he said. “My definition of a rock is a conglomeration of one or more minerals.” What's a mineral? These five criteria must be met: solid; naturally occurring; inorganic; has a fixed chemical composition and a definite crystal lattice structure. (Ice is a mineral, Jones said.)

There are three types of rocks:
·      Sedimentary–created by weathering and erosion.
·      Metamorphic–morphed by heat and pressure. Example: gneiss.
·      Igenous–formed from crystallization of molten, liquid minerals called magma. Two kinds of igenous: Intrusive–magma cooled slowly and seeped into adjoining rocks; example: granite. Extrusive–magma flowed from a volcano and cooled quickly; example: rhyolite.

What’s called Valley Spring gneiss (pronounced “nice”) formed from the heat and pressure of two plates colliding 1.3 billion years ago.

Before our field trip to see gneiss and granite, park interpreter Carol Navarro Adams encouraged us to share what we learn with others in a fun and even humorous way. “Our purpose as interpreters is not to instruct people but to provoke them so they’ll want to learn more about what they see,” she said. “First, we must connect with the natural world ourselves, then we connect to the needs of visitors, which are all different.”

Next, we drove to the park’s eastern end to hike the Devil’s Waterhole Trail. Jones led us up and over the rocks to a scenic overlook, where we gazed at a faraway waterfall while he furthered discussed geologic processes.

"You guys are lucky to get to see this," Sean Jones said. "Be sure and think about the geologic processes as you look around."

New signs welcome visitors to the Devil's Waterhole Trail.

Photos just don't do the scenery here justice! (I spotted a lizard waving its tail on the lower rocks but didn't get a photo of it.)

Heading up the trail.

Thanks to recent rains, a waterfall gushes along Valley Spring Creek.

Blair, a Master Naturalist with our chapter, pointed out this little guy to me. I believe it to be a greater earless lizard (Cophosaurus texanus). I've read that they wag their tags in the air above their bodies. 
(UPDATE MARCH 26, 2012–Lizard ID by Travis LaDuc with Herps of Texas and assistant curator, herpetology, Texas Memorial Museum.)

Blue curls

Another lizard of the same species near sedum. Their spots and coloring must keep them well camouflaged from predators.

At Devil's Waterhole, Jones pointed out gneiss and granite formations.

On a shaded bank that looks out to the Devil’s Waterhole, Jones concluded by talking about how Valley Spring Creek slowly washes sand into the lake’s delta.

“Since the dam was completed 73 years ago, 10 to 12 inches of sediments have been deposited,” he said. “Who knows, maybe in a million years, sandstone will form. That just shows you the power of water on our planet,” Jones concluded. “I can’t think of a geologic process that doesn’t have water as a part of it.”

Inks Lake is popular with kayakers. My daughter, Lindsey, and I paddled to this inlet a few years ago.

Back to our cars...the end of another fun and educational Master Naturalist class!

Our class curriculum sends us to the Lady Bird Johnson Wildflower Flower in Austin, where we'll learn about vanishing species, landscaping for wildlife (Texas Wildscapes...we know about those!) and tour the grounds. 

1 comment:

pat glenn said...

sheryl - i too have looked for arrowheads all my life and i have also only found one. it is perfectly shaped except the point is chipped off. found it on our property southwest of blanco. still lookin' for another one. i keep mine in a box for safety also.

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