First off, I think geologists would define Siphon Draw as a “feature”. It is not a Formation. Geologists have precise definitions for their jargon. We have started a glossary in the Geology Section to help with some of the terms.tibber wrote: Thanks to the keepers of the Geology tab... now I'm going to see if there is anything on the Siphon Draw formation as Joe and I had a discussion awhile back on what kind of rock Siphon Draw was...but I may have to come back here to ask
That being said, I am going to refer to parts of an article written by Tom Kollenborn and published in the AJ News. Tom is a respected authority on all things Superstition. You can google him and find out more info on Superstition Wilderness Legend & Lore.
"The geology of the Superstition Wilderness Area can be divided into three distinct categories. They include (1) rock type, (2) structure and (3) process. The rock type consists primarily of extrusive igneous rocks associated with vulcanism. Structure is consistent with the type of landforms that result from volcanic action and tectonic activity. The process is related to mass wasting, erosion, faulting, mountain-building and volcanic activity. All three of these categories contributed to the rugged and spectacular beauty of the Superstition Wilderness Area we enjoy today.
The western portion of the wilderness area is dominated by igneous rock whose origin is primarily volcanic action. There are examples of sedimentary and metamorphic activity within the boundaries of the wilderness; however this activity is very limited. There are Pre-Cambrian granites in a few isolated areas of the wilderness that were formed from intrusive igneous rocks. Intrusive rocks are formed from molten magma that cooled beneath the surface of the earth. In other words, the melt (magma) was not exposed to the atmosphere while it cooled. Eventually intrusive rocks are exposed on the earth’s surface by erosion.
Erosion is the wearing away process of the earth’s surface by wind, water and ice. These intrusive rocks can be found along the First Water Road and the Apache Trail (SR 88) northeast of Apache Junction. Granite diabase can be found east and south of the IV Ranch.
Common volcanic landforms found in the area include calderas, blister cones, lava flows, mudflows and ash deposits. Dacite, andesite, rhyolite, and breccia are the common igneous rocks found in the area.
. . .
The geology of the Superstition Wilderness Area is a fascinating study of igneous rock and their various formations. The rocks of the western portion of the Superstition Wilderness are eruptive igneous in origin. These rocks formed a wonderland of beautiful volcanic formations deposited between 3 – 25 million years-ago. We can only marvel the beautifully textured landscape the Superstition Wilderness Area provides for us."
The expert on Superstition Wilderness Geology was Dr. Michael Sheridan, Vulcanologist at Arizona State University from 1970-1989. There are some anomalies creating some disagreement on the exact processes in the geologic evolution but there is general agreement.
Dr. Ivo Lucchita in his book “Hiking Arizona’s Geology” has a detailed description of the Peralta Canyon Trail Geology on page 174.
If you made it all the way up Siphon Draw you will probably be glad to know that erosion has removed about 3,000 to 4,000 feet off the mountain.