Photos: Amazing Rocks from the Alamo Impact Crater
Sandstone formed from a sandbar built up around the crater's edge after the impact.
Credit: Carrie Johnson

Geologists first recognized in the 1990s that unusual rocks spread across Nevada's mountain ranges were from an impact crater. Now, researchers at Idaho State University have painstakingly mapped the thickness and position of different rock layers within the Alamo impact crater to precisely determine its size and shape. Check out these photos of the different impact deposits. [Read the full story about the Alamo impact .]

Alamo impact crater rocks exposed near Hiko, Nevada. (Photo credit: Leif Tapanila, Idaho State University)

Broken rocks in the Alamo impact crater deposits. (Photo credit: Rebecca Thorne-Ferrel)

Rippled sand marks the crater's edge, where a sandbar formed after the impact. (Photo credit: Leif Tapanila, Idaho State University)

Student Julia Steenberg in front of the Pahranagat Mountains, where the Alamo impact crater rocks are visible. (Photo credit: Leif Tapanila, Idaho State University)

The top of the Alamo impact breccia contains jumbled rock fragments. (Photo credit: Leif Tapanila, Idaho State University)

Coral reef fossils in rocks above the Alamo impact crater layers. (Photo credit: Leif Tapanila, Idaho State University)

Follow Becky Oskin @beckyoskin. Follow LiveScience @livescience, Facebook & Google+. Originally published on Live Science .