SIERRA MADRE AND PARTNER RIVERSIDE RESOURCES ANNOUNCE ADDITIONAL DRILL RESULTS FROM EL CAPITAN IN DURANGO, MEXICO

June 27, 2012 – Vancouver, BC: Sierra Madre Developments (“Sierra Madre”) (TSX-V: SMG) and its partner, Riverside Resources Inc. (“Riverside” or the “Company”) (TSX-V: RRI), are pleased to announce additional drill results from the 2012 drill program at the El Capitan Target (a near surface, shallow dipping, oxide gold deposit), which forms part of the Company’s Peñoles  Project in Durango, Mexico.  Drilling in 2011 indicated good continuity of the mineralized zone over a strike length of approximately 700 meters (referred to as the Main zone – see press release dated October 24, 2011) and the current program (funded by Sierra Madre) is designed to test the down dip extent of mineralization and provide sufficient drill hole density for an initial resource calculation.

The recently completed holes, CDDH 12-03 and CDDH 12-04, were drilled from separate drill pads in the central and west central parts of El Capitan.  CDDH 12-03 (drilled on the same section as CDDH 11-16 and 11-17) returned 65.5 meters of 0.606 g/t gold and confirmed the presence of the previously unrecognized “upper mineralized zone” localized within the porous volcanic agglomerates overlying the main mineralized zone at El Capitan (reported in CDDH 12-01 and 12-02).  Although the mineralization within the upper zone is not as consistent as the mineralization within the Main zone the average grade of the entire drill hole (138.1 meters) is 0.349 g/t.  CDDH 12-04 (drilled on the same section as CDDH 11-01) returned 44.2 meters averaging 0.670 g/t and also confirmed the presence of the upper mineralized zone.  Results from CDDH 12-03 and 12-04 are shown in the table below: (The true widths of the intercepts have not yet been determined but are believed to be approximately 90% of true width).

Drilling at El Capitan is continuing and assays will be released as they are received.  Preliminary results of the 2012 program are considered significant because El Capitan appears broadly similar to Argonaut Gold’ El Castillo Mine located approximately 90 kilometers south of El Capitan.  Argonaut Gold is successfully heap leach mining El Castillo at an average grade of 0.32 g/t gold with a cut-off grade of 0.15 g/t Au.

As previously announced (see press release dated October 12, 2011) preliminary bottle roll tests indicated that the mineralization at El Capitan may be amendable to low cost cyanide leach extraction.  To determine optimal leaching procedures Inspectorate Exploration and Mining Services of Richmond, BC has initiated systematic column leach testing utilizing approximately 1,200 kilograms of half core from the 2011 drill program.

There are ten other targets on the Peñoles Project including the recently announced Pinchanzo Zone (see press release dated May 23, 2012), potential west extensions of El Capitan (referred to as the West Extension), a new target area located to the northwest of El Capitan (referred to as Santa Theresa or Capitan Northwest Zone) and the previously mined Jesus Maria and San Rafael Ag- Au-Pb-Zn mines. Extensive surface sampling has been completed on several of the gold targets located near El capitan and results will be announced as they become available. The district is highly prospective with active mining operations nearby and has proven to be a safe and cost effective region where projects can be efficiently developed towards production.

Assaying and Qualified Person:

All drill core was placed in numbered boxes and transported to Sierra Madre’s secure core facilities by the drill contractor. Following detailed core logging all core was split using a diamond bladed core saw under the direct supervision of Sierra Madre’s Geologic staff. Half of the core was kept on site in the original core boxes, the second half was placed in labeled and sealed sample bags which were transported directly to the custody of Inspectorate, a laboratory certified for the provision of assays and geochemical analysis (ISO:9001-2008). Samples were transported to Inspectorate’s facilities in Durango, Mexico for prep work and analyzed at their facilities in Reno, Nevada. All samples were prepared using standard industry prep methods followed by fire assay analysis and aqua regia digest for trace elements. All samples with greater than 10 g/t Au were additionally tested by fire assay with a gravimetric finish. Sierra Madre has included 10% industry certified Au standards and blanks within the sample stream in addition to field duplicates as part of the QA/QC program.

The scientific and technical data contained in this news release pertaining to the Peñoles Project were prepared under the supervision of Carl Von Einsiedel, PGeo.,  a qualified person to Sierra Madre, and reviewed by David S. Smith, MS, MBA, CPG, a qualified person to Riverside Resources, who is responsible for ensuring that the geologic information provided in this news release is accurate and acts as a “qualified person” under National Instrument 43-101 Standards of Disclosure for Mineral Projects.

About Sierra Madre Developments: Sierra Madre is a TSX Venture listed junior mining company based in Vancouver, British Columbia, Canada. Management has extensive exploration and mining expertise and the Company’s business model is to acquire advanced gold and silver projects and build shareholder value by rapidly advancing our projects through the resource delineation stage.

ON BEHALF OF SIERRA MADRE DEVELOPMENTS INC.

“Carl von Einsiedel”

Carl von Einsiedel, CEO

For additional information contact: 604-685-3357

Certain statements in this press release may be considered forward-looking information. These statements can be identified by the use of forward looking terminology (e.g., “expect”,” estimates”, “intends”, “anticipates”, “believes”, “plans”). Such information involves known and unknown risks — including the availability of funds, the results of financing and exploration activities, the interpretation of exploration results and other geological data, or unanticipated costs and expenses and other risks identified by Sierra Madre in its public securities filings that may cause actual events to differ materially from current expectations. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release.

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