We have used Mars Exploration Rover Opportunity data to investigate the origin and alteration of lithic types along the western rim of Noachian-aged Endeavour crater on Meridiani Planum. Two geologic units are identified along the rim. The Shoemaker formation consists of two types of polymict impact breccia: clast-rich with coarser clasts in upper units; clast-poor with smaller clasts in lower units. Comparison with observations at terrestrial craters show that the lower units represent more distal ejecta from one or more earlier impacts, and the upper units are ejecta from Endeavour crater. Both are mixtures of target rocks of basaltic composition. Subtle compositional differences are caused by differences in post-impact alteration along the crater rim. The lower Shoemaker units and the Matijevic formation represent pre-Endeavour geology, which we equate with the regionally mapped Noachian subdued cratered unit. An alteration style unique to these rocks is formation of Si- and Al-rich vein-like structures crosscutting outcrops, and formation of smectite. Post-Endeavour alteration is dominated by sulfate formation. Rim-crossing fracture zones include regions of alteration that produced Mg-sulfates as a dominant phase, plausibly closely associated in time with the Endeavour impact. Calcium-sulfate vein formation occurred over an extended time period, including pre-Endeavour impact and after the Endeavour rim had been substantially degraded, likely after deposition of the Burns formation that surrounds and embays the rim. Differences in Mg, Ca and Cl concentrations on rock surfaces and interiors indicate mobilization of salts by transient water that has occurred recently and may be ongoing.