“I will not live long enough to fully appreciate what is on my property”
- Patty Duhon -
My husband and I moved to San Marcos 10 years ago and purchased property in the hills west of town. I started exploring our property and immediately noticed the rocks that littered the ground. There was such variety of shapes, colors and forms.
Growing up in Orange, Texas I was a rock enthusiast but did’t make many discoveries. I still have a couple of rocks from the fourth grade. I painted them with clear fingernail polish to bring out the vivid colors. I got my love of rocks from my Mom. On every trip, she collected a rock and would write the location and date found on the back. When she died, there was a BIG conversation about who would inherit her rocks. ; )
I am outside often working the garden and doing chores. While walking, my head is down scanning the ground for anything that catches my eye. After a heavy rain is always a good time to take a walk and hope to find something special. My efforts are often rewarded. I collect many beautiful pieces of flint and other mineral specimens, moving them to a pile, rock wall or add to a landscaping project. Over the years, the many rocks I collected resulted in displays throughout the yard and filled many bins with my favorite collections.
My early goal with the rock landscaping displays was to have something in the yard to share with my grandkids when they visit. I wanted them to join me on a walk looking for flint. I was a little saddened but not surprised when they were not interested. My favorite flint color is black with a white limestone coating the outside. Another favorite is blue with specks of white over the surface. These are hard to find, and it is always a treat to locate one.
Recently my husband and I started clearing a cedar grove which exposed a new area that had not been searched previously. There was so much beautiful flint, with several pieces showing signs of being shaped into tools. I sent a photo to Tom and invited him to come to San Marcos to walk the property with me and hopefully explain how these deposits were formed.
I first met Patty earlier this year as I was preparing to lead a geology walk on her property for a training class site visit. She showed me her extensive rock collection and asked me about how they were made and what created the unusual shapes. Patty and I share a love of rocks. Recently She asked me if I wanted to explore an area that was just exposed after clearing the cedar trees. I quickly accepted. We spent several hours walking her property, making new finds and looking at all of the interesting rocks she collected over the past 10 years. Patty agreed to collaborate with me on an article for the newsletter. I could help her understand the formation of flint, its importance in San Marcos and also share this information with the Chapter.
Flint, a variety of chert, is a sedimentary rock that can be found is many areas of Hays County. It is a hard and durable mineral formed from the silica (quartz) rich skeletal remains of marine organisms. Flint refers to the type of chert deposited in limestones. It is formed into nodules or in layers, which are referred to as ledge flint. It is common to see a thin layer of limestone covering the outside of the nodules, typically white and rough in texture. Flint varies greatly in color from white to black, but most often manifests as shades of gray, brown, grayish brown, light green and blue.
About 100 million years ago, large populations of very small organisms such a diatoms and radiolarians lived in shallow sea creating tiny structures made of biogenic glass or silica. Their silica remains accumulated in thick deposits on the sea floor, forming siliceous oozes. This process is relatively rare and only makes up about 15% of the sea floor. Both the limestone and flint were formed concurrently. That is why flint is found embedded into a limestone matrix. The floor of the shallow sea had marine worm holes and other burrows, creating narrow tubes and cavities in the sediment. The silica rich ooze filled these openings and hardened into the flint nodules we see today.
The abundant natural resources in eastern Hays County sustained populations for thousands of years at what is now known as Spring Lake. A key resource was flint. Flint was used to fabricate a wide variety of stone projectiles, points, scrapers, knives and other tools. It is not known if the flint on Patty’s property was quarried by these indigenous peoples. I think it is likely because its location is only a short hike from the springs. Another notable location is the famous Georgetown flint in Williamson county. Georgetown flint is the name given to an unusually good chert variety that occurs along the eastern fringe of the Edwards Plateau. Numerous artifacts include large and especially thin bifaces which were made from this material. Some of these tools were found hundreds of miles from the quarry. It is noted that flint deposits in Hays County are regarded as a ‘close cousin’ to Georgetown flint. Information on Georgetown flint was extracted from this interesting article, which can be viewed at this LINK:
Having the opportunity to visit Patty and explore her property was an incredible experience. Next time you are walking on your property after a good rain, keep your head down and you may be surprised at what you find.
Patty’s Addendum: Recently, my six year-old grandson spent time with me walking around the cleared areas over the holidays and got excited about finding and picking up pieces of flint! He even selected some “favorites” that he took home with him to Dallas. My Colorado grandson will be here in March. I’m hoping the weather allows us to go exploring for artifacts. I’m looking forward to spending time with like-minded grandchildren!
President – Susan Neill
Vice President - Yolanda Reyes
Secretary - Tracy Mock
Treasurer - Larry Calvert
Past President - Beth Ramey
State Representative and Volunteer Service Projects Director - Dixie Camp
TPWD Advisor - Gordon Linam
New Class Director – Mark Wojcik
Advanced Training - Beverly Gordon
Calendar - Beverly Gordon
Historian – Dana Martensen
Webmaster and Membership Director -Jane Dunham
Communications Director - Art Arizpe
Outreach Events - Paula Glover
Host Committee - Mary Dow Ross, Roxana Donegan
Newsletter– Tom Jones, Betsy Cross
Agrilife Sponsor- Jason Mangold
MN BOARD MEETING
When: Thursday Feb. 14 at 6:30p
Where: Agri-Life Extension office
200 Stillwater Drive Wimberley, TX 78676
When: Thursday February 28, 6:30pm – 8:30pm
Where: First Baptist Church - 203 W HWY 290
Dripping Springs, TX 78620
Please join us for a thrilling presentation on
Austin has more than 26,000 acres of land in the Barton Springs Recharge zone. Much of this land was over-grazed ranchland with poor vegetation and thus reduced aquifer recharge. Over the past 20 years this land has been and is being restored to its former native plant state. Restoration involves a combination of burning, replanting and invasive plant removal. Volunteers do not participate in burning but are very important to seed collection, seeding and invasive removal.
Participating in seed collection and reseeding is a great way to learn grasses and forbs. The Water Quality properties are lovely places to visit and work in. They also offer a number of other activities such as leading hikes and bird monitoring. There are a number of properties spread from west of Kyle to west of Austin. The way to join is to visit Austin Water’s website and click on the Water Quality Protection Lands and then Activity Calendar on the next page. You will need to register; once done log in and visit the calendar which lists the coming month’s activities. There usually are a number of different activities listed so you will need to search the list. You can then sign up---you will receive a confirmation in your email.
Water Quality Lands link: https://www.austintexas.gov/department/wildland-conservation-division/
For more information contact Dick McBride, email@example.com and 512-618-8669
The Discovery Center offers a great opportunity for earning your Master Naturalist volunteer hours. The majority of the work is in maintaining the gardens and that is a never- ending job; one can easily get 3-4 hours on each visit there. The DC’s primary goal is to demonstrate native plants but there is a smattering on non natives too. The DC is a great place to learn about forbs, shrubs and trees. San Marcos’ Arborist is headquartered there and happy to help you learn more about trees. The Discovery Center was formerly called the Nature Center. The name change was initiated when The Edwards Aquifer Authority’s Habitat Conservation Plan was relocated there. There is a lot going on at the DC and you can also participate in tree planting and mulching and invasive plant removal as well.
You can volunteer there any weekday but we do have weekly Tuesday morning work sessions. For more information contact Dick McBride; firstname.lastname@example.org and 512-618-8669.
I WAS CO-EDITOR OF THE HCMN NEWSLETTER FOR 1 YEAR
HERE ARE 5 THINGS I LEARNED
I spent the last 15 years of my career collecting water quality samples for the Texas Commission for Environmental Quality in the 22 county area of Northeast Texas. The two biggest water quality issues in that part of the State were bacteria and low dissolved oxygen (DO). In contrast, we hardly ever have low DO in the Hill Country because we have flowing streams compared to sluggish bayous.
How to interpret results
E.coli is found in the digestive system of all warm blooded animals. (It is not found in your urinary tract. If it is there, you are in trouble.) E.coli is used as an indicator organism in water quality sampling. There are only a few strains that are pathogenic. (Think of the recent romaine lettuce recalls because of E.coli 0157:H7.) The vast majority of strains are helpful, even necessary for digestion. So why test for it? It turns out that E.coli is a good indicator of the presence of many other pathogenic bacteria. When E.coli concentrations are high, the incidence of stomach related illness goes up in swimmers, but most likely because of pathogens other than E.coli. Water Quality Standards are compared to individual samples as well as for long-term averages. A single sample should not exceed 394 colonies/100 milliliters. But the more important regulatory sample result is the geometric mean (different from a simple average) of at least 10 samples collected over a relatively long period of time, at least one year.
When samples should be collected
It becomes very important when to collect samples for this geometric mean. It is very easy to bias the results. A random sample design is needed. If you target samples to one or two days after a rain, you will get more exceedances than if you were to randomly select the sample days. Everywhere in the state, bacteria concentrations spike after any rainfall event that causes runoff. Bacteria attach themselves to sediment particles. As long as the sediment is suspended in the water column, they are subject to being ingested by an individual. With time, these sediment particles settle and are no longer a concern. There is a group of individuals that collect bacteria samples in Wimberley on the first Monday after Market Days. This is random sample design and that is good.
Limitations of source tracking
Source tracking has its limits. It is expense and it is only as good as the regional “library” of data with which to compare. It can only tell you presence or absence, not relative importance. To my way of thinking, livestock and wild animal sources should be expected after a rainfall in just about every rural waterbody in Texas. Not so with human sources. They do not belong in the creek anytime. Properly run septic systems as well as city owned sewer systems should not contribute to the bacterial waste load of any waterbody.
Some common sense suggestions
Numerical standards are OK, but they give you yesterday’s data. The water you are swimming in today is miles downstream by the time the samples are read the next day. So it’s an educated guess as to the real water quality today. Young children are more likely to accidently ingest water while out on the river than are adults and therefore are at greater risk than adults. There are no guarantees in life, but keep the kids out of the river for 48-72 hours after a significant rainfall event and you should be good.
HCMN Rainfall project #803 has been updated to utilize the CoCoRaHS system. CoCoRaHS is an acronym for the Community Collaborative Rain, Hail and Snow Network. CoCoRaHS is a non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation (rain, hail and snow). CoCoRaHS provides precipitation data for many more sources/location for scientists to use. The Public can view at the historical data in CoCoRaHS from their website if you know the name of a site (TX-152-HYS is John Kluth’s). CoCoRaHS started in 1998, and has representation in all 50 states, Canada, and the Bahamas. View the CoCoRaHS website.
The requirements for becoming a CoCoRaHS volunteer, and thus be a part of Project 803 is a 4-inch diameter Rain Gauge. You may purchase one from a link found on the CoCoRaHS website. It has a capacity of up to eleven (11) inches of rainfall. You will also need to apply/register yourself as a volunteer which also is done from the CoCoRaHS website.
Once you have registered, you will be assigned an ID and a password to login to their system. You may log your observations on their website or you can download their APP to your Smartphone. This is a fast and easy way enter your data. Follow the instructions and recommendations on where to locate the gauge to increase measurement accuracy.
We will be making a large order for the new training class, which will be available of trainees (for any that wish to purchase one of these gauges. When we prepare to do that, watch your emails to find out when and who to contact to be included in that order. By being a part of a large order, you save on the shipping costs. You will need to be willing to attend a Chapter or Training meeting to be able to pick-up the rain gauge if you participated in a large order.
Please note that the HCMN Board recently decided that the maximum amount of volunteer time (VT) you may log per month for this project is 2.5 hours. This is based upon observing and logging data daily, with the estimate that it takes about 5 minutes each day to do so. Please only log the actual amount of time you spend, capped at 2.5 hours, for each month of your observations. Thus if you miss some days of logging (due to being out of town), and then enter a Multi-Day Report, you would therefore be logging multiple days of data, but only spend 5 minutes of time to do so.
Below are some screen shots from the CoCoRaHS phone app. This is from John Kluth’s CoCoRaHS login. He resides full-time in Northwest Harris County, part-time in far North Hays County. He has both of his properties registered with CoCoRaHS, and observes and records rainfall from both sites. He only logs into VMS the time each month that he empties his gauge in Hays County, thus much less that 2.5 hours per month for him.