Dinosaur Tracks and Footprints

If you're going to The Wave and have never seen a dinosaur track or footprint you should take a slight detour to see some. The tracks are only a ten minute detour from the route to The Wave. I would allow a half hour to get to the right area, find, and photograph the footprints. The prints are located at the foot of the cliffs on the west side of the permit area, just a bit north of The Wave. If you're hiking in to The Wave delay your crossing of the wash for a few hundred yards before turning east. On the way back from The Wave cross the wash as soon as you can after descending down the sand dune, hike a few hundred yards west to the base of the tall cliffs, and head south along the base of these cliffs.

The tracks are in the area just before the west side cliffs becomes difficult to ascend, in a reddish/white area. The footprints are generally about four inches long and are three toed (tridactyl). Claw impressions can be sometimes seen. The footprints are indented into the rock, and are sometimes filled with sand. They were most likely made by Grallators. Grallators lived about 200 million years ago (late Triassic / early Jurassic periods). To see an image of what a Grallator may have looked like click here. Two sets of footprints can be seen in my gallery. One footprint is near a large rock and is at 36° 59' 59.3" North, 112° 00' 34.0" West. The circled rock in the picture is about a yard in length, if you can find it you can find the footprint.

Track near large rock

The second set consists of two clear prints and a third possible print. The upper two prints in the below are very clear, the circled print at the bottom is degraded (200 million years!).

Best dinosaur tracks

These footprints are at 36° 59' 57.3" North, 112° 00' 35.6" West. To help you find the footprints I have placed a small circle of rocks around them. I normally do not like to create cairns (rock piles) as it takes some of the fun out of exploring an area. In this case I created the cairn since the footprints can be hard to find by a novice, and because there are many other footprints in the area for those who wish to find tracks on their own. Do not rely on the rock circle to find the prints, I'd be surprised if it's still there six months from now (written Feb. 2013). Update - early 2015, circle of rocks is still largely there.

The footprints can also be found by finding the large rock in the image above and then walking south along the base of the cliff about one hundred paces (80 yards).

Some notes on GPS accuracy

I've quoted the 95% accuracy of the GPS coordinates above at ten feet. This is the likely accuracy of the coordinates I have given, if your GPS only has an accuracy of thirty feet you could still be off by thirty feet or more when looking for the footprints. If you are looking for the tracks using a GPS be sure to enable WAAS if your receiver is so enabled.

GPS measurements were made with a WAAS capable receiver with WAAS turned on. The accuracy of GPS coordinates can vary greatly depending on the location of the GPS satellites in the sky, the quality of the GPS receiver, ionospheric characteristics at the time of reading, and whether any postprocessing was done. A high quality surveying GPS, like those made by Trimble, can cost $5,000 or more, and, with post processing, can have horizontal accuracy of ten centimeters after post processing. Good quality GPS receivers, like those made by Garmin, are typically accurate to within 30 feet without WAAS, or less than ten feet if WAAS is enabled. The accuracy figures above are at a 95 percent confidence level, e.g. for a WAAS receiver the GPS reported location is within a ten foot circle of the actual location 95% of the time.

Here are some other GPS concepts which relate to accuracy

Assisted GPS (AGPS) - some GPS chipsets such as those found in phones or tablets allow users to periodically download (via Wifi or 3G/4G ) information about exact satellite locations. This data is then used by the GPS to speed up acquisition times, or even, in some cases, to acquire a location when the GPS otherwise couldn't find one. Accuracy of location is not improved by AGPS however. Before I go out on a remote shoot I always download AGPS data to my tablet.

Differential GPS (DGPS) - Some GPS trackers/ devices have the ability to acquire a correction signal from "reference" ground stations. DGPS accuracy depends strongly on how far you are from the DGPS broadcasting station.

Wide Area Augmentation System (WAAS) - Since GPS receivers are often outside the coverage area of DGPS ground stations, the FAA collects measurements from ground reference stations and uploads this information to geostationary WAAS satellites. These satellites then broadcast the information back to those GPS receivers that are equipped to receive them. WAAS is a US term, it is called SBAS (satellite based augmentation system) by the International Civil Aviation Organization. WAAS is available throughout the United States and Hawaii. Locations in Alaska and northern Canada may have trouble getting a WAAS signal. 95% accuracy is better than ten feet. There are some disadvantages of WAAS, power usage is higher, and it may take more time to get a fix of a WAAS satellite than a normal satellite. WAAS may need to be enabled in the setup menu for your receiver. I have only recently started keeping WAAS on while I hike, so far power usage has been okay. Tablets and phones normally are not WAAS enabled. Current Garmin receivers can pick up WAAS signals.

Post-processing - The US maintains a series of ground stations of precisely known locations. Actual GPS signals are monitored at these known locations and corrections are developed. Corrections can then be applied to the logs created by some GPS receiver to get much more accurate locations. Unfortunately only very expensive (and heavy) receivers keep enough information in their logs to compute these corrections. Garmin and tablet receivers do not typically output the information needed for post processing. Post processing software can be expensive as well.

GLONASS - the Russian GPS system. It has world wide coverage. Recent Garmin receivers and most smartphones and tablets can receive GLONASS signals. The extra satellites can improve accuracy since more satellites in a better geometry are available for a fix. Recent Apple iPhones ( 4S and 5) and GPS enabled tablets (3G and 4G, not wifi only) can receive GLONASS signals, as can most android phones and tablets including the Google Nexus 7, and the Samsung Galaxy Tab 7.7.

If you are buying a GPS receiver for use in the US you should make sure that it is WAAS enabled and picks up GLONASS satellites.

 


This page was last updated 7/1/2015